BSE201 MOTOR DEVELOPMENT AND LEARNING STUDY GUIDE (5CU)Course Development Team Head of Programme : Dr James Ong Chye Hin Course Developer : Dr Esther Chia Lay Chern Production : Educational Technology & Production Team © 2017 Singapore University of Social Sciences. All rights reserved. No part of this material may be reproduced in any form or by any means without permission in writing from the Educational Technology & Production, Singapore University of Social Sciences. Educational Technology & Production Singapore University of Social Sciences 461 Clementi Road Singapore 599491 Release V1.2CONTENTS COURSE GUIDE 1. Welcome.............................................................................................................1 2. Course Description and Aims.........................................................................1 3. Learning Outcomes ..........................................................................................3 4. Learning Material .............................................................................................4 5. Assessment Overview......................................................................................4 6. Course Schedule................................................................................................5 7. Learning Mode ..................................................................................................6 STUDY UNIT 1 INTRODUCTION TO MOTOR DEVELOPMENT AND LEARNING Chapter 1 Motor Behaviour............................................................................ SU1-1 Chapter 2 Theoretical Perspectives in Motor Development...................... SU1-6 Quiz.................................................................................................................. SU1-14 Summary......................................................................................................... SU1-16 References ....................................................................................................... SU1-17 Solutions or Suggested Answers ................................................................. SU1-18 STUDY UNIT 2 PRENATAL AND INFANT DEVELOPMENT Chapter 3 Prenatal Development .................................................................. SU2-1 Chapter 4 Infant Development .................................................................... SU2-13Quiz.................................................................................................................. SU2-23 Summary......................................................................................................... SU2-24 References ....................................................................................................... SU2-25 Solutions or Suggested Answers ................................................................. SU2-27 STUDY UNIT 3 DEVELOPMENT OF CONTROLLED MOVEMENT Chapter 5 Development of Locomotion ....................................................... SU3-1 Chapter 6 Development of Manipulative Abilities................................... SU3-11 Quiz.................................................................................................................. SU3-20 Summary......................................................................................................... SU3-21 References ....................................................................................................... SU3-22 Solutions or Suggested Answers ................................................................. SU3-28 STUDY UNIT 4 DEVELOPMENT OF FUNDAMENTAL MOVEMENT SKILLS Chapter 7 Childhood Growth and Development ....................................... SU4-1 Chapter 8 Fundamental Movement Skills.................................................... SU4-7 Quiz.................................................................................................................. SU4-21 Summary......................................................................................................... SU4-23 References ....................................................................................................... SU4-24 Solutions or Suggested Answers ................................................................. SU4-27STUDY UNIT 5 ADOLESCENCE Chapter 9 Adolescent Growth ....................................................................... SU5-1 Quiz.................................................................................................................... SU5-9 Summary......................................................................................................... SU5-10 References ....................................................................................................... SU5-11 Solutions or Suggested Answers ................................................................. SU5-14 STUDY UNIT 6 ACQUISITION AND TRAINING OF SPECIALISED SPORT SKILLS Chapter 10 Introduction to Motor Learning ................................................ SU6-1 Chapter 11 Instruction and Augmented Feedback..................................... SU6-9 Chapter 12 Practice Conditions ................................................................... SU6-21 Quiz.................................................................................................................. SU6-31 Summary......................................................................................................... SU6-32 References ....................................................................................................... SU6-33 Solutions or Suggested Answers ................................................................. SU6-38COURSE GUIDEBSE201 COURSE GUIDE 1 1. Welcome (Access video via iStudyGuide) Welcome to the course BSE201 Motor Development and Learning, a 5 credit unit (CU) course. This Study Guide will be your personal learning resource to take you through the course learning journey. The guide is divided into two main sections – the Course Guide and Study Units. The Course Guide describes the structure for the entire course and provides you with an overview of the Study Units. It serves as a roadmap of the different learning components within the course. This Course Guide contains important information regarding the course learning outcomes, learning materials and resources, assessment breakdown and additional course information. 2. Course Description and Aims This course enhances the teacher's knowledge of the growth and motor behaviour of children from conception through to adolescence. It is a study of childhood growth and maturation as they relate to motor learning and skill acquisition. In the study of motor development, you will cover topics such as prenatal development, acquisition of gross and fine motor skills, development of fundamental movement skills and physical fitness changes with adolescence. Principles of cognitive, sensory, and motor processes which underlie the learning of motor skills commonly included in the physical education curricula, are addressed and applied to the instruction of motor skills to facilitate motor learning.BSE201 COURSE GUIDE 2 Course Structure This course is a 5-credit unit course presented over 6 weeks. There are six Study Units in this course. The following provides an overview of each Study Unit. Study Unit 1 - Introduction to Motor Development and Learning This unit introduces the key terms to the study of motor behaviour and provides a theoretical perspective to how motor development has evolved. Study Unit 2 - Prenatal and Infant Development This unit aims to give students an understanding to the major changes that occur during prenatal and infant development Study Unit 3 - Development of Controlled Movement The aim of this unit is to give students an understanding to the maturation process that underlie the development of locomotion and manipulation Study Unit 4 - Development of Fundamental Movement Skills This unit will give students an understanding to the growth process during childhood and the development of fundamental movement skills during this period of growth Study Unit 5 - Adolescence This unit describes the changes that occur during the adolescent period Study Unit 6 - Acquisition and Training of Specialised Sport Skills This unit covers concepts to the learning of specialised sport skill, and the use of instruction and feedback, and various forms of practice conditions to acquire a specialised sport skillBSE201 COURSE GUIDE 3 3. Learning Outcomes Knowledge & Understanding (Theory Component) By the end of this course, you should be able to:  describe the theoretical frameworks/models (i.e., Dynamical Systems and Information Process) and their application to teaching selected fundamental movement skills and specialised sports skills.  demonstrate a clear understanding of how movement skills develop as a result of growth.  describe the major changes that occur during prenatal and infant development.  discuss the maturation processes that underlie the development of locomotion.  observe and assess the proficiency of a child’s development of fundamental movement skills.  describe the changes that occur during the adolescent period and how they relate to changes in physical fitness.  demonstrate a working knowledge of the terms commonly used in motor development and motor learning for Sports Education.  explain the stages of learning identified by Fitts and Posner and apply the stages to teaching selected fundamental movement and specialised sports skills.  identify what motor skills are likely to benefit from demonstrations and how frequently demonstrations should be provided.  illustrate how practice scheduling and types of feedback enhances motor skill acquisition Key Skills (Practical Component) By the end of this course, you should be able to:  categorise movements (reflexive, rudimentary, fundamental, specialised sport skills).  identify qualitative performances of motor skill execution using the Total Body observation (phase/stage) and Component observation (body component/step) approaches to movement analysis of a variety of fundamental motor skills.BSE201 COURSE GUIDE 4  recognise and solve movement errors appropriately to learners’ stage of development in fundamental motor skills. 4. Learning Material The following is a list of the required learning materials to complete this course. Required Textbook(s) Haywood, K. & Getchell, N. (2009). Life Span Motor Development (5th ed.). Champaign, IL: Human Kinetics. Gallahue, D., Ozmun, J., & Goodway, J. (2011). Understanding Motor Development: Infants, Children, Adolescents, Adults (7th ed.). New York: McGraw-Hill. Magill, R.A. (2011). Motor Learning and Control (9th Ed.). New York: McGraw-Hill. 5. Assessment Overview The overall assessment weighting for this course is as follows: Assessment Description Weight Allocation Assignment 1 3 Pre-class online quizzes 5% Assignment 2 TMA01 20% Assignment 3 TMA02 25% Examination Closed book exam 50% TOTAL 100% The following section provides important information regarding Assessments. Continuous Assessment: There will be continuous assessment in the form of three pre-class online summative quizzes, on the 2nd, 4th and 6th week, and two tutor-marked assignments (TMAs). In total, this continuous assessment will constitute 50 percent of overall student assessment for this course. The three assignments are compulsory and are nonsubstitutable. These assignments will test conceptual understanding of both theBSE201 COURSE GUIDE 5 fundamental and more advanced concepts and applications that underlie motor development and learning. It is imperative that you read through your Assignment questions and submission instructions before embarking on your Assignment. Examination: The final (2-hour) written exam will constitute the other 50 percent of overall student assessment and will test the understanding and application of motor development and learning related concepts, theories and strategies to particular situations commonly faced by physical educators. All topics covered in the course outline will be examinable. To prepare for the exam, you are advised to review Specimen or Past Year Exam Papers available on Learning Management System. Passing Mark: To successfully pass the course, you must obtain a minimum passing mark of 40 percent for each of the assessments. That is, students must obtain at least a mark of 40 percent for the continuous assessments and also at least a mark of 40 percent for the final exam. For detailed information on the Course grading policy, please refer to The Student Handbook (‘Award of Grades’ section under Assessment and Examination Regulations). The Student Handbook is available from the Student Portal. Non-graded Learning Activities: Activities for the purpose of self-learning are present in each study unit. These learning activities are meant to enable you to assess your understanding and achievement of the learning outcomes. The type of activities can be in the form of Quiz, Review Questions, Application-Based Questions or similar. You are expected to complete the suggested activities either independently and/or in groups. 6. Course Schedule To help monitor your study progress, you should pay special attention to your Course Schedule. It contains study unit related activities including Assignments, Selfassessments, and Examinations. Please refer to the Course Timetable in the Student Portal for the updated Course Schedule. Note: You should always make it a point to check the Student Portal for any announcements and latest updates.BSE201 COURSE GUIDE 6 7. Learning Mode The learning process for this course is structured along the following lines of learning: (a) Self-study guided by the study guide units. Independent study will require at least 5 hours per week. (b) Working on assignments, either individually or in groups. (c) Classroom Seminar sessions (3 hours each session, 6 sessions in total). iStudyGuide You may be viewing the iStudyGuide version, which is the mobile version of the Study Guide. The iStudyGuide is developed to enhance your learning experience with interactive learning activities and engaging multimedia. Depending on the reader you are using to view the iStudyGuide, you will be able to personalise your learning with digital bookmarks, note-taking and highlight sections of the guide. Interaction with Instructor and Fellow Students Although flexible learning – learning at your own pace, space and time – is a hallmark at SUSS, you are encouraged to engage your instructor and fellow students in online discussion forums. Sharing of ideas through meaningful debates will help broaden your learning and crystallise your thinking. Academic Integrity As a student of SUSS, it is expected that you adhere to the academic standards stipulated in The Student Handbook, which contains important information regarding academic policies, academic integrity and course administration. It is necessary that you read and understand the information stipulated in the Student Handbook, prior to embarking on the course.STUDY UNIT 1 INTRODUCTION TO MOTOR DEVELOPMENT AND LEARNINGBSE201 STUDY UNIT 1 SU1-1 Chapter 1 Motor Behaviour Learning Outcomes By the end of this chapter, you should be able to: 1. distinguish between motor development and motor learning 2. describe the degrees of freedom problem as it relates to the study of motor control Overview The study of human behaviour has been of great interest to researchers, physical educators, parents and coaches for many years. Motor behaviour is an "umbrella" term referring to changes in motor learning control and development that embody learning factors and maturational processes associated with movement performance. The term motor behaviour is often used when we prefer not to distinguish between the three fields, or when we want to include both. As a physical educator, it is important to understand not only motor control, motor development and motor learning, but also how each of these influences the other.BSE201 STUDY UNIT 1 SU1-2 1.1 Defining Terms in Motor Behaviour Motor Development refers to the continuous, age-related process of change in movement, as well as the interacting constraints in the individual, environment, and task that drive these changes (Haywood & Getchell, 2009). Motor Learning refers to the relatively permanent improvement in the capability of a person to perform a skill as a result of practice or experience (Schmidt & Lee, 2005). Given that motor skills are defined as movements dependent on both practice and experience for their successful performance, a motor learning specialist is especially interested in the effects of practice variability, amount and distribution of practice, and learning situations on human movement (which would be further discussed in Unit 6). Motor Control is the study of the neural and physical mechanisms that underlie human movement. The nervous system in particular is central in producing movement as the neurons (nerve cells) stimulate the muscle fibres to generate a desired movement. Research in motor control examines questions and concepts that relate to movement and the underlying neural and physical variables. 1.1.1 Motor Control To successfully perform a variety of motor skills, we must coordinate various muscles and joints to function together. These muscle and joint combinations differ for many skills. For example, skills such as kicking and trapping involve muscles and joints of the trunk and lower limb, whereas skills such as writing or picking up a cup involve coordination of the arms, hands, and fingers. Furthermore, motor skill performance varies in the speed at which it is performed depending on the requirements of the movement tasks. For example, relatively slow movements are required for walking on a balance beam, whereas fast ballistic movements are required for jumping and sprinting. Lastly, some motor skills such as buttoning a shirt and reaching for an object have few component parts; other skills such as performing a dance routine or cascade juggling are very complex. Given the range of underlying requirements to perform a variety of motor skills, the field of motor control is concerned with the degrees of freedom problem. Degrees of Freedom Problem Degrees of freedom are the number of independent elements that must be constrained in order to produce coordinated motion (Bernstein, 1967). If we are to consider the task of reaching for a glass, there are a number of possibilities in which we coordinate and move our limbs to perform the same task. In the upper limb itself,BSE201 STUDY UNIT 1 SU1-3 the shoulder, elbow and wrist are involved in extending the limb (forward, diagonally or laterally) in the direction of where the glass is positioned. Because coordination involves head, body, and limb movement patterns, there are endless possibilities in which the nervous system controls the many muscles and joints involved in producing a given pattern. Therefore, the determination of successfully performing a movement pattern and achieving the task goal depends on how an individual is able to coordinate the movements with control to meet the demands of the task. Coordination involves constraining the number of degrees of freedom, in order to decrease the complexity of the movement task, so as to produce a movement pattern and achieve the task goal (Sparrow, 1992). Coordination involves individual groups of muscles and joints that must act together in proper relation to successfully perform the demands of the task. For instance, a basketball player has to constrain his degrees of freedom and control the initiation, release and power of the free throw in order to successfully perform a free throw shot. Discuss the degrees of freedom problem while performing the following motor skills: tennis serve, soccer penalty kick and dart throwing. 1.1.2 Motor Development Motor development is defined by several characteristics. Firstly, development is a continuous process of change in functional ability. Secondly, development is agerelated but not age-dependent. It is a life-long process beginning at conception and ceasing only at death. Thirdly, development involves sequential change where certain motor patterns precede others and are orderly in their appearances. These changes result from interactions both within the individual and between the individual and the environment. 1.2 Methods of studying Motor Development The field of motor development has been an area of study since the early part of the twentieth century. Motor development is currently being studied in three ways: the longitudinal method, the cross-sectional method, and the mixed-longitudinal method. Given that the study of motor development involves the study of changes that occur in motor behaviour over time, it is ideal to use the longitudinal method to study the entire length of the period we are interested in.BSE201 STUDY UNIT 1 SU1-4 The longitudinal method of data collection attempts to observe changes in behaviour over time (i.e. developmental time), with the purpose of measuring agerelated changes in behaviour. The longitudinal method involves the study of one group of individuals (all at the same age) to be observed repeatedly over several years. The longitudinal method although ideal, is very time consuming. In addition, large numbers of participants are often required to retain a representative sample at the end of the five to ten-year study due to the large dropout rates. Studies that are prolonged over a longer period also tend to have problems in data interpretation due to the varying levels of reliability and objectivity of testers over the course of the study period. Lastly, as the same participants are used repeatedly, the potential learning effects from previous performances on the measured items may also result in a more positive score on successive attempts. The cross-sectional method of data collection on the other hand is time-effective as it involves studying individuals from varying age groups, who are examined on the same measure once and at the same time. The cross-sectional method requires researchers to assume firstly that the random selection of research participants will provide a representative sample for each age group that is tested and secondly, that change in motor behaviour has occurred because of age difference. Therefore, the cross-sectional method allows for the study of age-related differences in behaviour, but not the age-related changes in behaviour. Consequently, one main limitation with cross-sectional method is the concept of age and cohort. Although participants are recruited based on age group, the cohort (generation group) in which the individual group is brought up in acts as a confounding factor, as the different age groups studied may have had different experiences in up-bringing. Therefore, to overcome the limitations of both the longitudinal and cross-sectional methods of research, researchers have designed the mixed-longitudinal method, which combines essential components of the longitudinal and cross-sectional methods. In a mixed-longitudinal method, participants from several age groups are recruited and studied over a short period of time, allowing for observation of both differences and change over time as a result of development and of age. Design three studies examining changes in handwriting, each using one of the different methods of studying motor development.BSE201 STUDY UNIT 1 SU1-5 You should now read Haywood, Kathleen & Getchell, Nancy. (2009). Life Span Motor Development (5th ed.). Human Kinetics. Chapter 1.BSE201 STUDY UNIT 1 SU1-6 Chapter 2 Theoretical Perspectives in Motor Development Learning Outcomes By the end of this chapter, you should be able to: 1. identify key researchers who contributed to this perspective 2. discuss how research has contributed to the knowledge of motor development 3. explain the importance of the normative and biomechanical descriptive periods 4. discuss the steps involved in the information processing perspective 5. demonstrate how information processing affects motor learning and performance 6. identify and expand on the two branches of the Ecological Perspective 7. demonstrate how the two branches of the ecological perspective can be applied to a specific motor behaviour Overview The study of motor development dates back to the 1920's where traditional study of motor behaviour was conducted through detailed observations of progressive changes in motor sequences. The history of motor development is commonly divided into four periods. It was during the precursor period (1787-1928) where works by Dietrich Tiedemann (1787) and Charles Darwin (1877) such as "A Biographical Sketch of an Infant" marked the beginning of this era. Tiedemann, in the observation of his son's development, discussed the sequences of movement behaviour, such as the grasp reflex to eventual voluntary grasping. Darwin's work however, led to a greater understanding of the processes of motor development. The precursor period was followed by the maturational period (1928-1946), where the study of maturation was the main focus in motor development research. At the end of World War II, during the normative/descriptive period (1946-1970), there was an increased interest by physical educators to develop standardised tests and norms. This period was lastly followed by the process-oriented period (1970-present) where there was a renewed interest in the hypothesis driven approach in the study of motor development. It is during this period where two perspectives of motor development emerged: information processing perspective and the ecological perspective.BSE201 STUDY UNIT 1 SU1-7 This chapter therefore aims to discuss the three main theories that have arisen from the study of motor development: maturational perspective, information processing perspective and the ecological perspective. 2.1 Maturational Perspective The maturational perspective attributes changes in motor development to the maturation process of the central nervous system. Maturationists therefore believe that motor development is an internal process that is driven by genetics and heredity, and that the environment (nurture) has little effect on the developmental process. 2.1.1 Arnold Gesell Gesell believed that:  Development was a reflection of the maturational process, placing heavy emphasis on biological variables.  Development progressed through an orderly sequence that was invariant from individual to individual, and that the sequence was determined through the biological and evolutionary history of humans.  The rate of development may vary from child to child, but is determined by the child's own hereditary background.  Environmental factors may temporarily affect motor development, however, biological factors ultimately determine the rate of development. Gesell's 2 basic principles of development 1. The principle of developmental direction Growth occurs in a cephalocaudal direction (head to tail). Infants would gain control of their head movements first, followed by their trunk and limbs. Growth concurrently occurs in a proximal-distal direction (central to peripheral). Infants gain control of their trunk at a faster rate than control of their limbs.BSE201 STUDY UNIT 1 SU1-8 2. The principle of individuating maturation This principle recognises the uniqueness of individual development, but emphasises that maturation is a process controlled by internal factors and cannot be influenced by external factors such as teaching. According to Gesell, learning can only occur when physical structures are developed to permit behavioural adaptation, and no amount of training before the development of those structures will be effective. This principle was based on the findings of an identical twin training study, where one twin was trained in stair climbing and the other was not. In this study, twin A was trained daily in stair climbing 6 weeks before the structures necessary to perform the task were thought to be developed. When the structures were thought to have matured, twin B was trained daily for two weeks in the same task. At the end of twin B's training, there were no differences between the twins in stair climbing. 2.1.2 Myrtle McGraw McGraw, like Gesell, believed that development emerged from the structural growth and maturation of the CNS. In other words, as the brain matures, motor behaviour improves (function). She believed however, that when conditions are favourable, there is a possibility that function (i.e. exposure to stimulation and/or movement or musculoskeletal activity) can modify the development of the peripheral and central structures that are involved in these events. McGraw's classic study of Johnny and Jimmy (McGraw, 1935) examined the influence of enhanced experience on motor development. From 12 - 22 months of age, McGraw provided Johnny with experiences relating to swimming, skating, tricycling, jumping, walking and crawling up/down slides and purposive manipulation of boxes. When Jimmy reached twenty-two months of age, he too was provided with two and a half months of intensive training in the same activities as Johnny. A main finding from this study was that there are critical periods dependent on the maturational status of the nervous system where improvement through practice becomes feasible. For example, when Johnny was introduced to tricycling at 11 months of age, he was unable to perform the skill until 20 months of age. Jimmy on the other hand, despite the lack of early stimulation, was able to perform the task with ease at 22 months of age. When assessed again four years later (McGraw 1939), performances by Johnny and Jimmy on most of the tasks were similar. However, it was noted that Johnny seemed to display a superiority of general muscular coordinations, which was attributed to the longer exposure to motor activities.BSE201 STUDY UNIT 1 SU1-9 Normative descriptive period After the end of World War II, which marked the end of the maturational period, physical educators began to be interested in describing children's motor skill abilities. The three physical educators who led this new era of study in motor development were Anna Espenschade, Ruth Glassow, and G. Lawrence Rarick. This marked the shift in emphasis on the study of motor development from a maturationist perspective to one that focused on the outcomes of motor development. Much of the emphasis was thus placed on the acquisition of movement skill in school-aged children, resulting in the emergence of the development of standardised gender specific norms in the performance of motor skills such as running and jumping. 2.2 Information Processing Perspective According to the information processing perspective, the brain receives input in the form of sensory information (i.e. visual, auditory, tactile and kinaesthetic), processes and interprets this information in order to produce coordinated movement. This perspective has been likened to a computer system, whereby computer-like operations occur as a result of an external input. Researchers during this period were interested in attending to the underlying process of motor development which focused on the functions of perception, memory, attention and effects of feedback. Within the information processing perspective, motor developmentalists began to study children's motor development from a perceptual-motor approach. An individual perceives information from his/her surrounding, which then leads to a voluntary movement. The information processing approach includes the following stages of processing (Schmidt & Wrisberg, 2008): 1. Stimulus identification: In this stage, the individual attempts to identify the stimulus which is received from the environment (i.e. visual, auditory, tactile and kinaesthetic). In addition, the individual may also detect patterns within the environment, which might provide important information in the determination of the response selection. 2. Response selection: Using the information received from the stimulusidentification stage, the individual would then move to the response selection stage, where he/she would decide how to respond to the stimulus. To do so, the individual would organise the sensory information and integrating it with previously stored information from past experiences (memory) to decide on the ideal response.BSE201 STUDY UNIT 1 SU1-10 3. Response Programming: Once the individual has selected a response, the action would then be programmed according to the response selected. This stage involves retrieving the motor programme for action, preparing the muscles and postural system for contraction and orientating the sensory system in the appropriate way. When the action has been readied, the motor cortex activates the muscle neurons to execute the desired movement, which produces an observable movement output. The end result of the three information processing stages is termed as the output, which is the motor behaviour or the movement produced. The output that is produced, however, might not necessarily achieve the desired outcome of the movement. For example, the soccer player might either score or miss a penalty kick; and a tennis player might or might not return a tennis serve. Apply the information processing theory to the performance of a motor skill. Discuss the factors that are to be considered in each stage of information processing. 2.3 Ecological Perspective The ecological perspective focuses on describing and explaining motor development through the interrelationship of the individuals to their environment and the task. The ecological perspective therefore considers the interactions of constraints that are present both within and outside the body in the development of motor skills. The ecological theory has two branches, one concerned with coordination (dynamic systems approach) and the other with perception (perception-action approach). The ecological perspective differs from the maturational perspective in that there is more than one system that affects the changes in motor development rather than only the Central Nervous System (CNS). In the ecological perspective, the ability to perceive the environment and organise muscles into groups for performing stable patterns of behaviour, is considered to reduce the executive function that is required of the brain, thus differing from the information processing perspective. Furthermore, the information processing theory does not account for the continuous interaction between the individual, the environment and the task. 2.3.1 Dynamic Systems Approach The dynamic systems approach sees motor behaviour as emerging from a continual interaction of the many subsystems in a task-specific context. As a complex system,BSE201 STUDY UNIT 1 SU1-11 motor development is considered to be non-linear and discontinuous. That is, behavioural changes over time do not follow a continuous, linear progression towards even higher levels of complexity, and are not necessarily smooth. Stability and attractors An important concept of the dynamic systems approach is self-organisation. Selforganisation is the individual's system of being able to emerge with a specific pattern of behaviour when certain conditions characterise a situation. The system is constantly looking for a stable state, suggesting that when the system is slightly perturbed, it will spontaneously return to a stable state. However, when the system is perturbed enough, it will be pushed into a new attractor, or stable state. For example, self-organisation to attractor states are observed in walk-to-run, or run-towalk transitions as a result of increases or decreases in speed of locomotion. During infant development, new attractors emerge as a result of changes in strength, body proportion, and coordination, causing previous attractor states to disappear. At the initial stage when infants start to walk, they would often revert back to crawling, which is their comfortable attractor state. However, with more experience in walking as well as increased gains in strength, they will lose the attractor state of crawling and develop walking as a new attractor state. Control parameters Control parameters are variables/factors that provide a condition for a new attractor state. Examples of control parameters include speed, weight, sensory information and injuries. In the example of a walk-to-run transition, the increase in speed acts as a control parameter, causing the individual to transition from walking to running. In motor development among infants, the state of instability with frequently changing components/subsystems, such as weight, strength, postural control and visual perception, results in the shifting of one attractor state to the next until a new preferred attractor state is firmly established, also known as phase shift. Examples of such phase shifts are crawling to creeping, and creeping to walking. Coordinative structures Coordinative structures are considered to be a collection of muscles and joints that act cooperatively for a particular situation or task. These coordinative structures may be achieved through practice, or experience, or they may exist naturally. Examples of coordinative structures are walking, running, and bimanual coordination which areBSE201 STUDY UNIT 1 SU1-12 gained through experience earlier on in life. In contrast, new coordinative structures can be gained through practice, such as serving a tennis serve. Interaction of constraints Karl Newell (1986) describes the dynamic systems theory from a constraints perspective, in which constraints are characteristics/factors from the individual, environment or task that encourage or limit movements. Individual constraints include structural and functional constraints that are unique to each individual's physical and mental characteristics. Structural constraints are considered to change with growth and ageing, which tend to be slow to change. Examples of structural constraints are height, weight, body composition (muscle mass) and body proportion. Functional constraints are related to behavioural function, which can change quickly, such as motivation, attentional focus and memory. Environmental constraints are factors that exist outside the individual's body. Examples of environmental constraints are temperature, humidity, lighting, overground surface and gravity. Task constraints are also factors that exist outside our body which are associated with the task, such as the rules, equipment and goals that are used for the sport. 1. Discuss how the dynamic systems theory explains the initial development of voluntary reaching and grasping action. 2. Consider a child with a movement disorder. How would individual and environmental constraints change in order for the child to walk in a crowded mall? 3. Consider how you can alter the task constraints to facilitate motor skill development in young children in the game of tennis. 2.3.2 Perception-Action Approach In the study of motor development, the perception-action approach studies the development of perception together with the development of movement behaviour.BSE201 STUDY UNIT 1 SU1-13 In addition, it considers the surrounding environmental factors in studying the individual's performance. Gibson (1979) proposed the term affordances to describe how an individual perceives the function that an environmental object provides to him/her based on the individual's structure (i.e. height, weight and strength) and the object's properties (i.e. size, shape, texture and weight). For example, when an infant starts to explore its surroundings, climbing the stairs is not perceived as possible due to its size and strength, thus the task is not considered to be afforded. However, when the toddler grows in size and strength, the perception of the function of the environment (which is to climb the stairs) becomes afforded. In addition to affordances, the concept of body scaling also provides an explanation for the development of human behaviour. The concept of body scaling suggests that although an object has a definite absolute size and shape, it has a function that is relative to the size and shape of the individual using the object. For example, a comfortable size and grip of a pen might be comfortable for an adult, but not for a toddler. Therefore, scaling the size of an environmental object to one's body size allows for movement patterns/motor behaviour that were previously impossible. Discuss how you would modify: 1. the environment at home to encourage movement development of an infant. 2. the game of volleyball to encourage the participation of the game. You should now read Haywood, Kathleen & Getchell, Nancy. (2009). Life Span Motor Development (5th ed.). Human Kinetics. Chapter 2.BSE201 STUDY UNIT 1 SU1-14 Quiz 1. As physical educators, teaching and providing relevant movement experience is an important aspect of assisting children to achieve successful skill performance. This process is also known as ____________. a) motor development b) motor learning c) motor control d) motor behaviour 2. The degrees of freedom problem develops as a result of the many __________ involved in producing movement. a) joints b) movement patterns c) muscles d) a and c e) all the above 3. The National Institute of Education is interested in conducting a study to examine the influence of the use of baby walkers in the development of walking. The best research design to be implemented would be the _________. a) longitudinal method b) cross-sectional method c) mixed-longitudinal method d) a and c 4. A study investigating the impact of neuromuscular development on the acquisition of postural control is considered to be characterised under the _________ perspective. a) maturational b) ecological c) information processingBSE201 STUDY UNIT 1 SU1-15 5. According to the dynamic systems theory, the infant's weight is considered to be a _________ in determining a phase shift from creeping to walking. a) affordances b) control parameter c) structural constraint d) b and c e) all the above 6. In performing a basketball free throw, which sequence best describes the information processing theory? a) retrieving previous experiences, sighting the hoop, planning the movement, determining the amount of power to throw the ball, throwing the ball, evaluating the performance b) sighting the hoop, planning the movement, retrieving previous experiences, determining the amount of power to throw the ball, throwing the ball, evaluating the performance c) sighting the hoop, retrieving previous experiences, determining the amount of power to throw the ball, planning the movement, throwing the ball, evaluating the performance 7. Which of the following researchers proposed the law of developmental direction? a) Charles Darwin b) Myrtle McGraw c) Arnold Gesell d) Karl NewellBSE201 STUDY UNIT 1 SU1-16 Summary Chapter 1 focused on introducing motor development, motor learning and motor control in the study of motor behaviour. The advantages and limitations of motor development research were discussed from the longitudinal, cross-sectional and mixed-longitudinal methods perspective. Only the longitudinal and mixedlongitudinal methods were able to examine change as a function of development as compared with the cross-sectional method. Chapter 2 reviewed the three main theoretical perspectives during the history of motor development, namely, maturational, information processing, and ecological perspective. The maturational perspective focuses on the maturation of the CNS which drives the development of motor behaviour. The information processing perspective views the information received from the environment as the driving force of motor development. The ecological perspective emphasises on the interaction of the individual's body systems, the environment and the task.BSE201 STUDY UNIT 1 SU1-17 References Bernstein, N.A. (1967). The coordination and regulation of movements. London: Pergamon. Gibson, J.J. (1979). An ecological approach to visual perception. Boston: Houghton Mifflin. Haywood, K., & Getchell, N. (2009). Life span motor development (5th ed.). Champaign, IL: Human Kinetics. McGraw, M.B. (1935). Growth: A study of Johnny and Jimmy. New York: AppletonCentury. McGraw, M.B. (1939). Later development of children specially trained during infancy. Child Development, 10, 1. Newell, K.M. (1986). Constraints on the development of coordination. In M.G. Wade & H.T.A Whiting (Eds.), Motor development in children: Aspects of coordination and control (pp.341-361). Amsterdam: Martin Nijhoff. Schmidt, R.A., & Lee, T.D. (2005). Motor control and learning: A behavioural emphasis. Champaign, IL: Human Kinetics. Schmidt, R.A., & Wrisberg, C.A. (2008). Motor learning and performance: A situationbased learning approach (4th ed.). Champaign, IL: Human Kinetics. Sparrow, W.A. (1992). Measuring changes in coordination and control. In J.J. Summers (Ed.), Approaches to the study of motor control and learning (pp.147-162). Amsterdam: Elsevier.BSE201 STUDY UNIT 1 SU1-18 Solutions or Suggested Answers 1. b) motor learning 2. d) a & c, joints and muscles 3. d) a & c, longitudinal and mixed longitudinal method 4. a) maturational 5. d) b & c, control parameter and structural constraint 6. c) sighting the hoop, retrieving previous experiences, determining the amount of power to throw the ball, planning the movement, throwing the ball, evaluating the performance 7. c) Arnold GesellSTUDY UNIT 2 PRENATAL AND INFANT DEVELOPMENTBSE201 STUDY UNIT 2 SU2-1 Chapter 3 Prenatal Development Learning Outcomes By the end of this chapter, you should be able to: 1. describe the process of prenatal growth 2. identify the different movements that occur in-utero 3. explain the functional significance of foetal movements 4. discuss several nutritional, hereditary and environmental factors that may affect later development 5. describe the influence of maternal exercise during pregnancy on foetal development Overview The first half of this chapter focuses on the process of normal foetal growth from conception to birth. This process would detail the physical growth that occurs during the different stages of development (zygotic period, embryonic period, early foetal period and late foetal period). In addition, the prenatal movements that are observed during each period are described, together with the development of the nervous system. The second half of this chapter aims to discuss the hereditary, nutritional and environmental factors that affect prenatal and postnatal development.BSE201 STUDY UNIT 2 SU2-2 3.1 Zygotic Period (Conception - 1st Week) Growth begins at the moment when fertilisation occurs. The genes contributed from each parent would then direct and determine one's development and genetic potential. The zygotic period is marked by rapid cell division through a process called mitosis. By the end of the first week, the zygote begins to implant itself in the wall of the uterus. 3.2 Embryonic Period (Week 2 - Week 8) The embryonic period is characterised by rapid cell division and the differentiation of the embryonic stem cells into specialised cell types/layers (endoderm, mesoderm and ectoderm), eventually forming tissues, organs and systems. Table 2.1 shows the various systems that develop from the specialised cell layers. Following the differentiation of the three embryonic layers, the embryo also undergoes a simultaneous head-tail and lateral folding, so that the flat embryonic disc develops to form a cylindrical structure.BSE201 STUDY UNIT 2 SU2-3 Table 2.1 Systems that develop from embryonic germ layers Cell Layer Systems Endoderm (inner layer) Digestive tract Respiratory system Glandular system Mesoderm (middle layer) Muscular-skeletal system Circulatory system Reproductive system Ectoderm (outer layer) Nervous system Epidermis (skin, hair, nails) (Source: Adapted from Gallahue, Ozman, & Goodway, 2011) By about 4 weeks of gestation, the embryo has a basic circulatory system via the umbilical cord, where nutrients such as oxygen, proteins, and vitamins from the maternal blood can pass through to the embryo; and digestive wastes such as carbon dioxide from the embryo's blood pass back through to the mother. Although the placenta is able to filter the maternal blood of harmful substances into the embryo, most drugs however do pass through the placenta. In addition, at 4 weeks, the embryo's heartbeat can be detected, together with the formation of lungs and limb buds (bone ossification beginning). By the end of the embryonic period, the eyes, ears, nose, mouth and fingers are formed, with the sensory organs developing. Finally, the first movements of the foetus are observed, such as the startle reflex, slight facial movements, and hiccupping.BSE201 STUDY UNIT 2 SU2-4 Movements observed due to neural development Neurons begin developing in the embryonic period at about week 3 as the neural plate starts to fold. With the development of neurons, the first human synapses in the nervous system also appear. These early synapses are formed in the spinal cord between interneurons and motorneurons at about 6-7 weeks of gestation. At the same time, the muscle fibres are being formed, allowing efferent and afferent neuromuscular connections to develop. The increase in early synapses and innervation of muscle fibres by motorneurons corresponds to the early observations of foetal movements. Therefore, the first detectable movements of the foetus are considered to originate from spinal motorneurons. 3.3 Early Foetal Period (Week 9 - Week 28) Physical Growth 9-12 weeks At the beginning of early foetal period, the foetus is about 4 cm in length. During these few weeks, sexual differentiation continues, with the sexual organs being visible by the end of the 12th week. The stomach and kidneys begin to function with the ability of the foetus to urinate. 13-16 weeks During this period, the foetus grows to about 15-20 cm in length, and weighs about 170 g. The hands are fully shaped, and the lower limbs begin to lengthen. Hair follicles also develop on the scalp of the foetus. 17-20 weeks The foetus grows to 20-26 cm in length, and weighs about 230 g. Lanugo hair (very fine, soft hair) covers the entire body of the foetus. Eyebrows and fingernails also appear. Foetal movements are felt by the mother as the foetus continues to grow rapidly in the limited space.BSE201 STUDY UNIT 2 SU2-5 21-24 weeks The foetus is about 33 cm in length and weighs about 450 g. The vernix (fatty secretion) protects the delicate skin of the foetus, and the lungs produce surfactant which is vital to respiratory function. At this stage, if the foetus is born prematurely, although the foetus has the capacity to survive outside the womb, most born at this time will not survive. 25-28 weeks By the end of the 28th week, the foetus is about 36 cm long and weighs approximately 900 g. The foetus is also fully structurally complete, and there are regular periods of rest and movement by the foetus. Movements observed due to neural development More movements can be observed in utero. These movements include the startle reflex, grasping reflex, walking reflex, facial expressions, swallowing and rhythmic “breathing” of amniotic fluid, isolated arm/leg movements, isolated movements of the head, jaw opening, sucking and swallowing, hand/face contact, stretching, and yawning. Beginning at about 13 weeks, the reflexive movements that are considered to be activated by the spinal motorneurons are slowly overtaken by goal oriented movements, reflecting the maturation of the foetal brainstem. Movements observed include moving the hand to hand, hand to mouth, hand to face, hand to eye, and hand to ear (Kurjak et al., 2003). As a result of the myelination of the brainstem and the development of synaptic connections from the auditory nerve through to the primary auditory cortex, behavioural responses to sound have been observed at 20 weeks of gestation (Hepper & Shahidullah, 1994). Eye movements are only observed around 16 weeks of gestation due to the later onset of midbrain maturation (Woitek et al., 2013). Furthermore, with 4 D sonography, a full range of facial expressions including, smiling, crying and eyelid movements similar to emotional expression in adults have also been observed.BSE201 STUDY UNIT 2 SU2-6 3.4 Late Foetal Period (Week 29 - Week 37+) Physical growth 29-32 weeks There is rapid increase in weight as the foetus develops a layer of adipose tissue under the skin. The foetus at this stage would be 41-46 cm in length, weighing approximately 1.8-2.5 kg. Most of the lanugo hair and vernix is lost, and there is an excellent chance of survival if foetus is delivered now. 33-36 weeks The foetus continues to grow till about 48 cm in length and about 2.7-3.5 kg in weight. The lungs mature, allowing for a 100% chance of survival if delivered. 37 weeks + Normal gestation period is about 40 weeks, and the infant is usually about 48-56 cm long and weighs about 3-4 kg. In the last month, the fatty deposits become more evenly distributed under the skin, and the skin loses its red colour. Movements observed due to neural development Towards the last 10 weeks of gestation, there is a decrease in the amount of foetal movements. This decrease in movements have been attributed to a decrease in amniotic fluid, and the maturation of the cerebral cortex. During this time, at about week 33, the foetus begins moving to a head-down position for birth. It has also been found that the foetus at about 33 weeks of gestation is able to remember and distinguish between familiar and novel stimuli. In one study, mothers at 33 weeks of gestation were asked to read a rhyme aloud daily for 4 weeks. At 38 weeks of gestation, the same rhyme was played, and it was found that foetal heart rates dropped in response to the familiar rhyme. However, when a novel, unfamiliar rhyme was played, foetal heart rates remained unchanged, therefore suggesting that the foetus was able to learn the sound patterns at about 33 weeks of gestation (DeCasper et al., 1994). Discuss the development of the nervous system and how it is reflected in foetal motor activity.BSE201 STUDY UNIT 2 SU2-7 3.5 Why is Prenatal Motility Important? Reflective of the developing nervous system As described in earlier portions relating to movements observed due to neural development, it details foetal motor activity that is activated from spinal motorneurons, which are then slowly overtaken by goal oriented movements, reflecting the maturation of the foetal brainstem. Researchers have described the relationship between foetal motor activity and optimal neonatal motor and reflex performance as one that contributes to the conservation of motor functioning from prenatal to postnatal periods (Amiel-Tison, Gosselin, & Kurjak, 2006; DiPietro et al., 2010). Necessary for normal anatomical and physiological development Research has found associations between foetal motor activity and new born maturation (DiPietro et al., 2010). It was suggested that greater foetal motor activity provides practice that contributes to the development of the musculature and potentiates the neural circuitry associated with more optimal neonatal motor performance and reflex responsivity (DiPietro et al., 2010). Furthermore, foetal inactivity does not allow for adequate bone-loading movements such as stretching, kicking and turning, which has also been suggested to slow the development of muscle mass (Miller, 2005). 3.6 Factors Affecting Prenatal Development 3.6.1 Hereditary Factors 1. Chromosome-based disorders Humans have a total of 46 chromosomes, with each chromosome containing up to 20,000 genes. It is estimated that 1 in 150 babies are born with chromosomal abnormalities, which are caused by errors in the number or structure of the chromosomes. The most well-known chromosomal abnormality is that of Down syndrome. Instead of having two number 21 chromosomes, individuals with Down syndrome have three. The rate of incidence is age related, with the chances of having an affected baby increasing with age. Children with down syndrome have varying degrees of mental retardation, and rate of growth is slower than normal. They are often shorter in stature, accompanied with shorted limbs. In addition, heart defects are also commonly found in these children.BSE201 STUDY UNIT 2 SU2-8 Other examples of chromosomal abnormalities are that of Patau's syndrome (no. 13) or Edward's syndrome (no. 18), but children with these chromosomal abnormalities seldom survive beyond birth. 2. Gene-based disorders Genetic defects are caused by one or more abnormality to the genome. The severity of the disorder depends on whether it is on a autosomal or sex-linked chromosome. Mental retardation and motor developmental delay are commonly found in individuals with autosomal recessive mutations such as sickle cell disease, talipes and phenylketonuria. 3.6.2 Nutritional Factors 1. Maternal diet Foetal nourishment has a great potential to positively and negatively affect growth. The foetus is nourished with oxygen and nutrients through the maternal blood via the placenta. The mother therefore plays an important role in providing for the foetus needs through her diet. Poor maternal diet often results in low birth weight, which accounts for nearly 50-60% of infant deaths. Similarly, poor nutritional diet is also suggested to contribute to poorer health status of the infant which may lead to other birth defects such as spina bifida. 2. Drugs Given the porous nature of the placenta wall, it also allows other chemicals or harmful substances from the mother to be passed on to the foetus. During pregnancy, the pregnant mother may still require the use of medication to manage an illness or disease. However, during this time, it is important that the prescription of medication is modified to protect the foetus. The specific effect a drug has on the foetus also depends on the foetal stage of development, with more vulnerable periods during the development of tissues and organs. Use of legal drugs such as asprin, caffeine and streptomycin has been shown to affect foetal development; implications such as low birth weight, infant death around the time of birth, poorer motor development, and lower intelligence scores in early childhood have been reported. Similarly, alcohol consumption during pregnancy is considered to be one of the most common causes of birth defects. Alcohol consumption is associated with damage to the nervous system, mental retardation, facial defects (i.e. narrow eyes, flat midface, underdevelopment of the jaw and thin upper lips), deficits in psychomotor abilities (i.e. decreased joint mobility, poor coordination and motor developmental delay), and behavioural problems.BSE201 STUDY UNIT 2 SU2-9 Furthermore, the use of illegal drugs has also been found to affect foetal development with greater incidences of miscarriages and infants born with low birth weight. The use of heroin has been associated with premature birth, low birthweight, breech birth, respiratory problems and physiological withdrawals such as vomiting, diarrhoea and fever. The use of cocaine by pregnant women have also been found to contribute to increased infant mortality, low birth weight, hypertension, malformation of the urinary tract, withdrawal symptoms, mental disabilities and behavioural problems. 3.6.3 Environmental Factors 1. Maternal stress Prenatal maternal anxiety has been a cause of concern for the development of the foetus. Prenatal stress/anxiety may cause the release of high doses of cortisol and catecholamines, resulting in a diminished blood flow, thus decreasing the amount of oxygen and nutrient to the foetus, which might in turn interfere with an adequate development of the central nervous system. Most researches have reported prematurity and low birth weight to be associated with maternal anxiety. In addition, a research by Brouwers and colleagues (2001) examined the effect of maternal stress on subsequent infant development, and reported lower mental development scores at the age of 2 years and deficits in attention related processes. 2. Maternal illness Human Immunodeficiency Virus (HIV) Pregnant women who carry the human immunodeficiency virus are at risk of transmitting this virus on to their foetus. HIV infection can be transmitted to the foetus in one of three ways: (1) in utero, (2) during the delivery when the foetus comes into contact with infected blood or vaginal secretions, and (3) from breast feeding. Infants born with HIV tend to be smaller in stature and weight for their age, fail to attain developmental milestones at their expected age, and have impaired brain growth and poor muscular strength. The average lifespan of infants with the disease is 24 months. However, children who do live past the age of two, will not survive past the age of 13, with majority manifesting the symptoms of the disease at four years of age. Rh incompatibility Rh incompatibility occurs when the blood types between mother and child are incompatible. When a Rh-negative mother is expecting a Rh-positive foetus, if any Rhpositive blood cells escape from foetal circulation to enter maternal circulation, it will cause the mother to produce antibodies against the Rh-positive cells. However, as theBSE201 STUDY UNIT 2 SU2-10 bloodstreams of the foetus and mother do not mix, this seepage of foetal blood occurs mostly until later pregnancy, with the mother developing antibodies postnatally. If subsequent Rh-positive offspring is exposed to the antibodies produced by the Rhnegative mother, they develop erythroblastosis fetalis, which is characterised by anaemia and jaundice. However, this condition can often be avoided with the mother receiving an injection of anti-D IgG immunoglobin immediately after her first delivery, thus preventing the build-up of antibodies. Diabetes mellitus Diabetes in an expectant mother exposes the foetus to a constantly altering metabolic environment, ranging from normoglycemia to hypoglycemia to hyperglycemia. Maternal hyperglycemia leads to increases in foetal glucose resulting in an increase in foetal secretion of insulin, thereby inducing foetal hyperinsulinemia. The increase in insulin production causes an increase in glycogen levels in the foetal liver, which leads to an increase in triglyceride synthesis in fat, ultimately resulting in increased foetal body fat. Other characteristics of this condition is: (1) the inhibition of maturation of lung surfactant, (2) muscle weakness or cardiac arrhythmias, and (3) possible neurological damage caused by neonatal hypoglycemia. 3. Maternal exercise Exercise during pregnancy has always been an issue involving controversy. Some of the concerns relating to exercise during pregnancy are: (1) injuries which may result in miscarriages, (2) persistent vaginal bleeding, (3) ruptured membranes, and (4) low birth weight. Furthermore, exercise during pregnancy also poses greater danger to the health of the expectant mother, such as increased susceptibility to injuries, lumbar lordosis, and back and hip pain. However, exercise during pregnancy has also been found to have certain benefits to both mother and the unborn child. Exercise during pregnancy benefits the mother by reducing complications during delivery, delivering closer to the due date, lower fat retention, and maintenance or improvement of cardiovascular fitness during pregnancy. Benefits to the foetus include: (1) decrease body fat, which may decrease susceptibility to obesity later in life, (2) more mature cardiac autonomic nervous system, and (3) improved stress tolerance. Expectant mothers who exercise regularly are therefore encouraged to maintain their exercise levels during pregnancy with guidance of the physicians and consistent selfmonitoring. Expectant mothers who were sedentary with no medical contraindications (such as pregnancy-induced hypertension, prior history of preterm labour and incompetent cervix) are encouraged to engage in light to moderateBSE201 STUDY UNIT 2 SU2-11 physical activity for 30 minutes a day, or several bouts of 10 minutes throughout the day. 4. Maternal age Teenage pregnancy has been associated with infants born with low birthweight which increases the infant's risk of mental retardation, learning difficulties, respiratory problems and immature organ systems. Furthermore, substance abuse increases stress levels and poor medical care increases the infant’s susceptibility to prematurity and increased mortality. Expectant mothers who are older are also found to have a higher chance of conceiving a child with chromosome-based or gene-based disorders. 5. The birth process The birth process is a long and painful process for most expectant mothers. Furthermore, the stress that the mother experiences during child birth is also experienced by the foetus, which may put the foetus at risk. In situations whereby the foetus is in the wrong position or in distress, intervention (such as malpresentation, use of forceps or caesarean deliveries) by the attending physician may be required. Each however, comes with certain dangers. Malrepresentation is the altering of the position of the foetus by the attending physician or midwife in the event that the foetus is in the wrong position. This however has been associated with the incidence of mental retardation, learning difficulties and cerebral palsy. The use of forceps has also posed as a danger to both mother and foetus through their overuse and misuse. However, current practices use the forceps in events of emergency when the foetus heartbeat is weak or when the baby's oxygen supply is compromised. Lastly, caesarean deliveries are considered to be a major operation whereby an incision is made in the abdominal wall and uterus to deliver the foetus. This form of delivery although having its own advantages (no contractions and pain in the vagina), the risks to both foetus and mother are great. Caesarean deliveries have been found to be associated with premature birth, breathing problems and low APGAR scores (Appearance, Pulse, Grimace, Activity and Response) in infants. Therefore, despite the advances in caesarean deliver techniques, obstetricians advise against the use of caesarean deliveries, unless in emergency situations. What advice would you give to your friend who is expecting her first child?BSE201 STUDY UNIT 2 SU2-12 You should now read Gallahue, David, Ozman, John, & Goodway, Jacqueline. (2011). Understanding Motor Development: Infants, Children, Adolescents, Adults (7th ed.). McGraw-Hill. Chapter 5.BSE201 STUDY UNIT 2 SU2-13 Chapter 4 Infant Development Learning Outcomes By the end of this chapter, you should be able to: 1. describe the physical growth of an infant 2. discuss the influence of physical growth on motor development 3. distinguish between survival and postural reflexes 4. discuss the purpose of infantile reflexes on later voluntary movement behaviour 5. outline the developmental sequence of acquisition of initial stability, locomotor and manipulative abilities 6. describe the development of voluntary movement of an infant from 0-6 months Overview The growth process of an infant in the first two years is the first of two periods in which rapid physical growth occurs. Furthermore, the first few months of the infant’s life is one that is of great interest to both researchers and parents. The first few months are filled with infantile reflexes which occur in a manner for the infant to obtain nutrition from the mother as well as protection from the environment. These reflexes are subcortical in nature and over a period of the first few months, these reflexes disappear to give way to more controlled movements due to the maturation of the cerebral cortex. There are two main types of reflexes, the primitive infantile reflexes which are related to infant survival, and the postural reflexes which act as precursors to the development of voluntary movement. The onset of voluntary movement follows a cephalocaudal (head-to-tail) and proximal-distal (central to peripheral) direction, explaining for the control of the head and neck muscles, followed by the trunk and limbs.BSE201 STUDY UNIT 2 SU2-14 4.1 Infant Growth The first two years of growth occurs rapidly in an infant, which will also influence the development of motor skills. For example, the proportion of the head to the rest of the body would affect balance and similarly, the size of the hand would determine the size of object that he/she can grasp. Neonatal period (Birth to 4 weeks) During the neonatal period, the head of the new born is still proportionately larger than the rest of the body, accounting for a quarter of the body. The size and weight of the head, as well as the lack of development of the neck and postural muscles make it impossible for the neonate to gain control of the head. The typical length of a newborn is about 48-53 cm, whereas weight tends to vary according to the socioeconomic and nutritional status of the mother. A good nutritional diet of the mother, a positive psychological well-being and a nurturing environment are critical for optimal growth of the neonate. Early infancy (4 weeks to 1 year) The first year of infancy involves rapid growth in terms of height and weight, although there are little changes to body proportion. The average height of an infant reaches about 76 cm, and weighs about 10 kg by the time it reaches 1 year of age. At about 6 months, the thorax region is slightly larger than the head, which allows for more balance and stability in the upper body, giving rise to better postural control. Later infancy (1 year to 2 years) The second year of growth continues at a rapid pace, but slows down a little as compared with the first year of growth. By the age of 2 years, the infant is about 88 cm in length, and weighs approximately 12.5 kg. Following Gesell's law of directional trend of development, the development of body segments occurs at different times. The growth of the upper arm precedes that of the lower arm and hand. The second year of growth marks the onset of the changes in body proportions to the end of the adolescent period, in which the trunk grows at a moderate pace, with the limbs lengthening at a faster rate to reach optimal growth. The changes in length and body proportion allow for greater ability of the child to gain postural control. Furthermore, the increases in the length and strength of the limbs will also allow for reaching and grasping actions to be performed by the child.BSE201 STUDY UNIT 2 SU2-15 You should now read Gallahue, David, Ozman, John, & Goodway, Jacqueline. (2011). Understanding Motor Development: Infants, Children, Adolescents, Adults (7th ed.). McGraw-Hill. Chapter 6. 4.2 Infantile Reflexes Reflexive movements are involuntary movements that are stimulated by external stimuli, with the same stimuli eliciting the same specific reflex movement each time. Reflex movements are movements that are initiated and controlled by the lower brain centres and are present in the prenatal foetus and new born. Some examples of reflexive movements in adults are breathing, sneezing, yawning, and the patella reflex. Early reflexes present in infants are categorised as either primitive survival reflexes or primitive postural reflexes. 4.2.1 Primitive Survival Reflexes Primitive survival reflexes are considered to be important for the nourishment and protection of the infant. They first appear at birth, but disappear at different times depending on the type of reflex. Moro and startle reflex While the infant is in a supine position, the Moro and startle reflex can be elicited by tapping the abdominal or pillow, or self-induced by the infant's cough or sneeze. The Moro reflex is identified by the extension of the arms and legs, with the fingers spreading, following by the flexion of the arms and legs. The startle reflex differs slightly from the Moro reflex; there is no extension of the arms and legs, but instead it is initiated by the flexion of the arms and legs in response to the stimulus. The Moro reflex disappears at about 3 months, and if the reflex persists past 6 months of age, it may be indicative of neurological dysfunction. The startle reflex on the other hand appears at 7 months and disappears at about 10 months of age. Searching or rooting and sucking reflex The search or rooting reflex enables a new born to obtain nourishment from the mother by searching for the nipple. When the infant's cheek or side of the mouth is stimulated with a smooth touch, the infant will turn its head towards the direction of the stimulation. Once the stimulus (nipple or milk bottle) comes into contact with theBSE201 STUDY UNIT 2 SU2-16 lips or the inside of the mouth (tongue, gums or hard palate), this will initiate the sucking motion (sucking reflex). The searching or rooting reflex appears at the time of birth and disappears at 1 year of age, whereas the sucking reflex appears at birth and disappears at 3 months, with the sucking motion occurring as a voluntary response. Palmar grasping reflex The palmar grasping reflex is stimulated when an object comes into contact with the infant's palm and the infant responds by closing all four fingers tightly around the object. Despite only having four fingers close around the object, the grip is surprisingly forceful, and if both hands are stimulated, the adult can lift the infant off the ground. The palmar grasping reflex can be observed prenatally and disappears at about 4 months of age. Palmar mandibular reflex (Babkin reflex) The babkin reflex is elicited when pressure is applied to the palms of both hands, and the responses usually include the opening of the mouth, closing the eyes, and flexing the neck thus tilting the head forward. It is suggested that this reflex is important for young animals to cling to their mothers when feeding. This reflex is present at birth and disappears after 3 months of age. Plantar grasping and Babinski reflex Upon applying pressure on the ball of the foot, the toes will contract around the object stroking the foot, known as the plantar grasping reflex. The Babinski reflex on the other hand is stimulated by an upward stroking of the sole of the foot from the heel to the toes. This stimulation will elicit a response in which the infant extends, spreading its toes. Both the Plantar grasping and Babinski reflexes are present from birth, with the plantar grasping reflex disappearing at 12 months, and the Babinski reflex disappearing at 4 months of age. Asymmetrical tonic neck reflex To elicit the asymmetrical tonic neck reflex, the infant is placed in a supine position, with the examiner turning the infant's head to either side. When the infant's head is turned to the right side, this will cause the infant's right arm and leg to extend, with the left arm and leg assuming an acute flexed position. The asymmetrical tonic neck reflex is present prenatally and disappears at 4 months.BSE201 STUDY UNIT 2 SU2-17 Symmetrical tonic neck reflex When an infant is supported in a sitting position, the symmetrical tonic neck reflex can be elicited by tipping the head backwards or forwards. When the head is extended back, this will cause the infant's arms to extend and the legs flex. If the head is flexed forward, the infant will flex the arms and extend the legs. Persistence of this reflex is suggested to hinder development of voluntary head movements as well as inhibit reaching and grasping, unsupported sitting and other major milestones. The symmetrical tonic neck reflex is present at birth and disappears at about 3 months of age. 4.2.2 Primitive Postural Reflexes Primitive postural reflexes enable a newborn to automatically maintain an upright posture in relation to its environment. Most postural reflexes occur after the first 2 months, when there is some form of musculature support. Labyrinthine righting reflex When an infant is supported upright and tilted forward or backward, this will elicit the labyrinthine righting reflex. The infant would attempt to maintain upright position of the head by moving it in the opposite direction when the trunk is tilted. For example, if the infant is tilted downwards (prone position), the infant would respond by lifting its head upwards. The labyrinthine righting reflex appears at 2 months and disappears at 12 months of age. Pull-up reflex The pull-up reflex is stimulated when the infant sitting upright and held with 1 or both hands will flex his/her arms to maintain an upright position when tilted forwards or backwards. The pull-up reflex appears at 3 months and disappears at 12 months of age. Parachute reflex The parachute reflex is a protective reflex whereby there is a sudden displacement in body position, and the visual responses of its environment stimulate the parachute reflex. There are various stimuli and responses of the parachute reflex. When the infant is held upright and suddenly lowered to the ground, the legs will extend and abduct in a manner to protect itself from the fall. Similarly, when the infant is held upright and suddenly tilted forward in a prone position, the arms will extend in an attempt to cushion the fall. The parachute reflex appears at about 4 months of age and persists into adulthood.BSE201 STUDY UNIT 2 SU2-18 Crawling reflex To elicit the crawling reflex, the infant is placed in a prone position on the ground, and the soles of the feet are stroked alternately. The stroking of the foot would cause the infant to produce a return of pressure thus causing the arms and legs to move in a crawling-like action. The crawling reflex is present at birth and disappears about 3 months of age, before voluntary crawling begins at about 6 months of age. This reflex has been suggested to be a prerequisite in the development of musculature for future voluntary crawling. Stepping reflex The stepping reflex can be elicited by holding the infant upright with both feet touching the ground, causing the infant to alternately lift and then lower the leg. Although resembling that of walking, this step reflex only involves the movement of the lower limbs. The stepping reflex has been observed in utero and disappears after 5 to 6 months. It has however, been suggested by several researchers that the stepping reflex can be exercised to strengthen the lower limb muscles and speed up the onset of voluntary walking in infants (Bower, 1976; Thelen & Fisher, 1982; Zelazo et al., 1972). Swimming reflex When an infant is held in a prone position in or above water, it will elicit swimminglike movements, by displaying rhythmical extensor and flexor movements of the arms and legs. The swimming reflex has been observed as early as the second week of life and disappears at four months of age. The crawling reflex, stepping reflex and swimming reflex can also be considered as locomotor reflexes as their movements are reflective of locomotor activities. These reflexes appear and disappear much earlier before the actual onset of the corresponding voluntary movements. 4.2.3 Persistence of Primitive Reflexes As described in each of the infantile reflexes, these reflexes appear mostly at birth and disappear after a few months. In addition, as reflexes are controlled by the lower brain centres of the central nervous system, it is common for paediatricians to use these reflexes as a diagnostic tool for central nervous system disorders. If the reflex that is tested is absent, excessively weak, irregular, asymmetrical or persists past the period at which it should disappear, further testing would need to be conducted to examine for any neurological dysfunction.BSE201 STUDY UNIT 2 SU2-19 Two common reflexes that are used for physical examinations of the infants are the Moro reflex and the asymmetrical tonic neck reflex. The Moro reflex may indicate neurological damage when the reflex persists beyond 6 months of age, or if the reflex response is asymmetrical. The asymmetrical neck reflex may also provide evidence of cerebral palsy or neural damage if one side of the response is weaker than that of the opposite side. Therefore, neurological dysfunction of the infant is usually suspected when: (1) the reflex persists beyond the age at which it should disappear, (2) there is complete absence of the reflex, (3) it elicits asymmetrical reflex responses, or (4) responses are too strong or weak. 4.2.4 Relationship of Reflexes to Voluntary Movement As mentioned earlier on, the role of primitive survival reflexes is to enable the infant to obtain nourishment and protection. However, for many of the primitive postural reflexes, it has been suggested that they play a more important role in the development of voluntary movements. There are two main theories contending for and against the notion that early postural reflexes directly prepare the infant for later voluntary movement. The first is the maturational theory, which states that the development of the cortex inhibits some of the lower cortical functions (such as reflexes) and then facilitates movement under a different and higher level of cortical control (McGraw, 1943). This theory explains for the disappearance of the reflexes for several months before the onset of the corresponding voluntary movement. The second theory is the dynamic systems theory which suggests that constraints in physical growth of the individual or the environment may act as rate limiters to the onset of voluntary movement. Early research by Zelazo and colleagues (1972) investigated the influence of stimulation of the stepping reflex on voluntary walking movements. They found that the infants that received active walking exercises had greater walking responses which were better executed than the infants in the control group, suggesting that active-exercise infants seemed to progress from a reflexive to a voluntary response. Therefore, it was recommended that retention of the stepping reflex through active exercise may facilitate motor development, thus encouraging the earlier onset of mobility. Further research by Thelen and Fisher (1982) observed that the stepping reflex disappeared at the same time when the infants gained large amounts of fat mass in their lower limbs. This suggested that the disappearance of the reflex was related to the increase in weight of the legs and the biomechanically demanding upright posture, instead of the maturation of the cerebral cortex. Subsequently, Thelen and Fisher (1982) examined the persistence of the stepping reflex by manipulating the mass on the legsBSE201 STUDY UNIT 2 SU2-20 by adding weights or submerging them in water. They found that when they increased the mass on the legs, they could inhibit the stepping reflex, while decreasing mass on the legs (via submersion in the water), they were able to restore the reflex. This therefore provides evidence that factors such as body proportions, body weight and muscular strength may act as rate limiters for the emergence of voluntary movements. Describe how some of the infantile reflexes relate to survival of the infant. Discuss the role of infantile reflexes in the development of voluntary controlled movement. You should now read Haywood, Kathleen & Getchell, Nancy. (2009). Life Span Motor Development (5th ed.). Human Kinetics. pp.99-109. 4.3 First Voluntary Movements As the primitive reflexes in the infant begin to disappear, more purposeful movements which are controlled by the higher brain centres begin to emerge. As mentioned earlier, the maturation of the cerebral cortex inhibits lower cortical functions and then integrates the sensory and motor systems to produce voluntary controlled movement. The first few voluntary movements observed during infancy are known as rudimentary movements. The development of these rudimentary movements usually follows through a sequential and predictable sequence, in which attainment of each movement enables for the practice and achievement of the following movement. The progressions in which these rudimentary movements are achieved are also known as motor milestones. Nancy Bayley (1935) in an extensive study, charted the typical motor behaviour across the first three years of life. From the data collected, Bayley developed a scale of infant development charting the progressive acquisition of rudimentary movements in infants. Figure 2.1 is an adaptation of Bayley's infant scale of development, which depicts the onset of the various milestones that occur from birth to the first 6 - 8 months. Bayley attributed this progression of movement skill acquisition to the maturation of the central nervous system, development of the infant’s musculature,BSE201 STUDY UNIT 2 SU2-21 development of stability in posture and balance, and improvement of sensory processing. Furthermore, as mentioned in Unit 1, Arnold Gesell stated the principle of developmental direction, in which infant growth occurs in a cephalocaudal and proximal-distal direction. Therefore, infants would gain control of their head movements first, followed by their trunk and limbs. Similarly, the sequence in which categories of rudimentary movements develop is from one of stability, followed by locomotive and manipulative skills. For example, the infant would need to be able to maintain control of its posture (upright sitting or standing upright independently) before being able to locomote (crawl or walk) and move its arms against the force of gravity to reach and grasp for objects. Therefore, in this instance, stability and strength of the infant are considered to be rate limiters, as the infant needs to be able to push its trunk off the ground and stabilise the body in a prone position before being able to crawl. Chin and chest up Rolls over Sits with support Reaches for objects Sits without support 0 1 2 3 4 5 6 7 8 Age (months) Figure 2.1 Motor developmental milestones in the first 6 - 8 months (Source: Adapted from Bayley, 1935) 4.3.1 Head and Neck Control Voluntary control of the head is the first to be observed within the first month after birth. Initial control of the head is seen by the infant's ability to hold the head erect while being supported at the base of the neck. Similarly, the infant is able to turn itsBSE201 STUDY UNIT 2 SU2-22 head while lying supine. Subsequently, greater voluntary control of the head is evident by the end of the second month, where the infant is able to elevate its chin off the mattress while lying in a prone position. Throughout the next few months, the infant gains greater control, being able to hold its head in an erect position without neck support, as well as turn its head from one side to another while lying in a prone position. By the end of the fifth month, the infant has good control of the head, being able to raise the head while lying in a supine position. 4.3.2 Trunk Control Following the cephalocaudal principle of motor development, after infants gain control of their head and neck muscles, they begin to gain control of the muscles in the upper trunk region. As evident in the second month, the infant is able to lift its head off the mattress in a prone position, which leads to the observation of trunk control, whereby the infant would also be able to elevate the chest off the mattress. From 3 to 6 months of age, the infant continues to gain greater control of the trunk muscles allowing for the infant to attempt to roll from a supine to prone position. By the age of six months, the infant is usually successful in rolling from a supine to prone position. In addition, with greater head and trunk control, the infant is able to sit while assisted, and would be able to independently perform the task of sitting at about 5-6 months of age with increased lumbar control. 4.3.3 Upper Limb Control Upper limb control is generally observed in infants at about 4 months of age. Movement that is initiated at the shoulder and elbow tends to be slow and uncoordinated. While reaching for the object, movements of the hand tend to be uncoordinated with repeated opening and closing of the hand. At the fifth and sixth month, the infant becomes much more coordinated with smoother movements in the shoulder, elbow and wrist, with greater accuracy in movement. Discuss the relationship between physical growth and the first voluntary movements. Discuss some of the constraints influencing the development of the motor milestones.BSE201 STUDY UNIT 2 SU2-23 Quiz 1. At which stage of prenatal development does movement first occur? a) Zygotic period b) Embryonic period c) Early foetal period d) Late foetal period 2. Why is it important for foetal development? 3. Which of the following is not a primitive survival reflex? a) Moro reflex b) Labyrinthine righting reflex c) Asymmetrical tonic neck reflex d) Rooting reflex 4. What does the persistence or absence of primitive reflexes most likely indicate?BSE201 STUDY UNIT 2 SU2-24 Summary The first chapter of this unit described the development of the foetus from conception to birth in terms of physical growth as well as prenatal movements which reflect the maturation of the central nervous system. The last section of Chapter 3 discussed a wide variety of factors that affect prenatal as well as later development. Today, there is a greater awareness of lifestyle changes that can be made to protect the development of the unborn child, such as avoiding the consumption of alcohol, illegal drugs, and moderating the use of prescribed drugs. A good and substantial diet will provide the foetus with the required nutrition and vitamins for healthy growth. In addition, given the benefits of exercise during pregnancy, health-care providers should encourage their patients to participate in regular physical activity to reduce complications during delivery as well as to benefit the unborn foetus. Growth in a newborn occurs rapidly in the first two years after birth. The infant grows to about twice its length and quadruples its weight by the time it is 2 years old. Along with changes in length and weight, body proportions also change slightly, with the thorax region growing slightly larger than the head. Along with physical growth, the maturation of the cerebral cortex also explains for the appearance and disappearance of certain reflexive movements, as well as the facilitation of the first voluntary movements. Infantile survival reflexes under control of the subcortical region of the brain function in order for the infant to maintain survival. Primitive reflexes such as the searching/rooting reflex and the sucking reflex allow for the infant to obtain nourishment from the mother, whereas the parachute reflex for example, allow for some form of protection for the infant. There have been two main theories attempting to explain the relationship between the function of primitive reflexes for the onset of later voluntary movement. The maturationists believe that there is no direct relationship between primitive reflexes and those of voluntary movement, and inhibition of reflexes only reflects the maturation of the cerebral cortex. However, the dynamic systems theory suggests that the disappearance of reflexes only occurs as they are not practised, and other constraints such as strength and fat mass prevent the exercise of the reflex, thus the gap between the disappearance of reflexes and the corresponding voluntary movements. Lastly, motor development as stated by Gesell occurs in a cephalocaudal and proximal-distal direction, with the infant gaining control of the head first, followed by the trunk and the limbs. The control of these first forms of rudimentary movements will provide a stable foundation for the infant to develop further locomotive and manipulative skills.BSE201 STUDY UNIT 2 SU2-25 References Amiel-Tison, C., Gosselin, J., & Kurjak, A. (2006). Neurosonography in the second half of fetal life: A neonatologist’s point of view. Journal of Perinatal Medicine, 34, 437- 446. Bayley, N. (1935). The development of motor abilities during the first three years. Monograph of the Society for Research on Children Development, 1, 1-26. Bower, T.G.R. (1976). Repetitive processes in child development. Scientific American, 235(5), 38-47. Brouwers, E.P.M., van Baar, A.L., & Pop, V.J.M. (2001). Maternal anxiety during pregnancy and subsequent infant development. Infant Behavior and Development, 24, 95-106. DeCasper, A.J., Lecaneut, J., Busnel, M., Granier-DeFerre, C., & Maugeais, R. (1994). Fetal reactions to recurrent maternal speech. Infant Behavior and Development, 17(2), 159-164. DiPietro, J.A., Kivlighan, K.T., Costigan, K.A., Rubin, S.E., Shiffler, D.E., Henderson, J.L., et al. (2010). Prenatal antecedents of newborn neurological maturation. Child Development, 81(1), 115-130. Gallahue, D., Ozman, J., & Goodway, J. (2011). Understanding motor development: Infants, children, adolescents, adults (7th ed.). McGraw-Hill. Hepper. P.G. & Shahidullah, B.S. (1994). Development of fetal hearing. Archives of Disease in Childhood, 71(2), F81-87. Kurjak, A., Azumendi, G., Vecek, N., Kupesic, S., Solak, M., Varga, D., & Chervenak, F. (2003). Fetal hand movements and facial expression in normal pregnancy studied by four-dimensional sonography. Journal of Perinatal Medicine, 31(6), 496-508. McGraw, M.B. (1943). The neuromuscular maturation of the human infant. New York: Columbia University Press. Miller, M.E. (2005). Hypothesis: Fetal movement influences fetal and infant bone strength. Medical Hypotheses, 65, 880-886. Thelen, E. & Fisher, D.M. (1982). Newborn stepping: An explanation for a "disappearing reflex". Developmental Psychology, 18, 760-775.BSE201 STUDY UNIT 2 SU2-26 Woitek, R., Kasprian, G., Lindnder, C., Stuhr, F., Weber, M., Schopf, V., Brugger, P.C. et al. (2013). Fetal eye movements on magnetic resonance imaging. PLoS ONE, 8(10), e77439. doi:10.1371/journal.pone.0077439. Zelazo, P.R., Zelazo, N.A., & Kolb, S. (1972). "Walking" in the newborn. Science, 176(4032), 314-315.BSE201 STUDY UNIT 2 SU2-27 Solutions or Suggested Answers 1. b) Embryonic period 2. - Reflective of the developing nervous system - Necessary for normal anatomical and physiological development 3. b) Labyrinthine righting reflex 4. Neurological dysfunctionSTUDY UNIT 3 DEVELOPMENT OF CONTROLLED MOVEMENTBSE201 STUDY UNIT 3 SU3-1 Chapter 5 Development of Locomotion Learning Outcomes By the end of this chapter, you should be able to: 1. describe the maturation of feedback control in the development of postural control 2. discuss the effect of maturation and training on the development of postural adjustments 3. outline the developmental sequence in the acquisition of locomotor abilities 4. comment on the interaction between maturation and the various constraints on the development of prone locomotion 5. distinguish between creeping and crawling 6. comment on the interaction between maturation and the various constraints on the development of upright gait 7. describe the typical walking gait 8. discuss the functional significance of the characteristics observed in an infant's walking gait 9. identify the factors affecting development of infant walking gait Overview Independent walking is a major fundamental locomotor task that develops during the first two years after birth that involves a complex dynamic inter-relationship of the individual, the environment and the task involved. The process in which walking behaviour develops can be seen as a series of postural changes in which the child achieves neuromuscular control to assume upright posture first, then the ability to maintain upright posture, walk with support, and finally walk independently. This chapter aims to describe the sequence in which infants acquire these motor patterns, as well as to discuss the interaction between environmental opportunities and restraints and the individual's growth and maturation to determine the onset of locomotive skills of the child.BSE201 STUDY UNIT 3 SU3-2 5.1 Development of Postural Control 5.1.1 What is Postural Control? Postural control is the act of maintaining balance and position in space. In order to maintain balance, postural control involves responses to perturbations that occur externally, as well as adjusting one's movements to maintain equilibrium while performing voluntary movements (such as manipulative or locomotive movements). The control of posture itself is a behaviour, and is required to assist with stability in the performance of motor skills. Postural control has been suggested to be achieved in two ways. Firstly, postural adjustments to external perturbations are direction specific (Forssberg & Hirschfeld, 1994). For example, a slight forward movement of the body while sitting or standing would trigger the back muscles of the body to maintain balance. Similarly, if balance is compromised by a backward sway, this would induce activity of the ventral muscles to maintain balance. It has been observed that direction specific postural responses are active even before the infant is able to sit unassisted, suggesting an innate origin of these motor patterns (Hadders-Algra, Brogren, & Frossberg, 1997). Secondly, in human movement, afferent information is obtained from various sensory receptors to the brain. This feedback therefore provides constant information to the brain about the progress of movement, which allows for adjustments in movement if necessary. Feedback consists of three components: (1) vestibular, visual and somatosensory systems for maintaining balance, (2) integration of information from the sensory systems to allow for planning of postural adjustments, and (3) execution of movement to correct for posture. Vestibular, visual and somatosensory systems The vestibular system includes a number of complex structures which are responsible for registering head motion as well as accompanying body motion which are important to balance activities. The vestibular system consists of two subsystems, the semi-circular canals and the otolith organs (utricle and saccule). The semicircular canals are also referred to as angular accelerometers as they detect rotational movements of the head. The otolith organs, on the other hand, provide information regarding the linear and gravitational acceleration of the head. Therefore, the ability of the vestibular system to detect head position and head movements in space, provides rapid sensory information to the brain to enable the immediate generation of appropriate postural responses to maintain both static and dynamic balance.BSE201 STUDY UNIT 3 SU3-3 Vision provides an objective source of information that allows an individual to judge his/her position, orientation, and movement in space. In a classical "moving room" experiment by Lee and Aronson (1974), participants were asked to stand in a room, whereby although the floor was stationary, the walls could move forward or backwards. The movement of the wall together with the stationary floor created a conflict in sensory input necessary for postural control, whereby vision indicated that they were moving, but the somatosensory input indicated that they were stationary. They found that children tended to believe their vision more than their somatosensory input, and made more postural correction adjustments in attempt to maintain balance. Somatosensory information is an important source of feedback allowing for the maintenance of balance. Postural control for maintaining an upright posture is considered under a closed loop control system, in which proprioceptive information allows for an individual to make movement corrections to maintain posture. Owen and Lee (1986) suggested that the slower development of the proprioceptive system in infants could explain for the higher reliance on visual information while maintaining balance. 5.1.2 Postural Control in Infants In the first few months of the infant's life, there are a number of individual constraints present in infants which limit the development of postural control. Some individual constraints include a high centre of mass (large head and torso), higher proportion of fat than muscles, and an underdeveloped neuromuscular system. However, it has been observed that infants as young as 1 month old are able to generate direction specific postural adjustments while sitting, suggesting that postural control at this level is of an innate origin (Hedberg et al., 2004). At about 6 months onwards, the infant develops the ability to adapt postural activity to specific situations, whereby experiences through trial and error enable infants to select specific postural adjustment patterns (also known as en bloc patterns) which provide the best stabilisation of their head or trunk in space. The ability of the infant to adapt their postural control has therefore been attributed to the achievement of a significant motor milestone of sitting independently (Hadders-Algra, 2005). Hadders-Algra and colleagues (1997) also explored the impact that training had on the development of postural control. They found that although training accelerated the initial stages in postural control development, the non-trained infants followed close behind in abilities by 1-2 months. The authors therefore suggested that the early presence of direction specific postural adjustments reflects the innate and central origin of postural control.BSE201 STUDY UNIT 3 SU3-4 From 9-10 months of age, during external perturbations, infants display an increased control over postural adjustments by making small changes to the amount of muscle contraction of the direction specific muscles. With increasing age and the development of independent standing, infants continue to learn to select from a variety of postural patterns to provide the best stability. Subsequently, with their ability to stand independently, their strategy to maintain balance changes to an ankle or hip strategy, whereby rapid flexion around the joint is activated first in response to a perturbation (Roncesvalles, Woollacott, Brown, & Jensen, 2004). Furthermore, with the development of walking, it is observed that infants begin to use the ground as an additional source of sensory information to maintain balance (Barela, Jeka, & Clark, 1999; Metcalfe & Clark, 2000). It is only at about 13-14 months of age when infants begin to integrate feed-forward control into postural management (Witherington et al., 2002). Explain the importance of postural control in the development of locomotive skills. 5.2 Development of Prone Locomotion 5.2.1 What is Locomotion? Locomotion is the ability of an individual to transport the body in a horizontal or vertical direction from one place to another. Locomotive skills include crawling, walking, running, rolling, skipping, galloping and jumping. Similar to the first onset of voluntary movements, locomotion develops in a predictable manner, although the rate and manner at which these locomotive skills are acquired may vary considerably from child to child. In addition, there are several constraints of the individual and the surrounding environment that must allow for the development of infant locomotion. 5.2.2 Factors Involved in the Development of Locomotion As mentioned in Unit 2, from birth, the infant begins to rapidly acquire control of its body accordingly from head to toe in a cephalocaudal direction. Furthermore, at the age of about 6 months, with increased lumbar, upper and lower limb control, the infant is able to independently perform the task of sitting. Therefore, with the increased ability to voluntarily control the body segments, it facilitates further development of other movements during infancy. Furthermore, as movementsBSE201 STUDY UNIT 3 SU3-5 function against gravity, there is a need for infants to develop stable structures before being able to locomote. It was initially thought that the development of movement patterns was solely a reflection of the development of the central nervous system (McGraw, 1943). However, with increased studies conducted in the area of motor development, it is evident that changes in patterns of motor behaviour are dependent on a variety of factors, including not only neurological but biomechanical and task constraints as well, with no one factor privileged relative to the others. For example, Thelen (1985) showed that developmental changes in bilateral alternation of leg movements were influenced by changes in body composition (relative ratio of muscle to fat in legs), as well as postural position of the infant. This was contrary to the traditional view where it was believed that changes in motor behaviour reflected the maturation of the nervous system. Given that a variety of individual constraints such as body proportions, muscular strength, postural control and maturation of the motor cortex are necessary for changes in motor pattern behaviour, the infant is unable to locomote until these systems of functional stability are mastered. 5.2.3 Crawling and Creeping During infancy, the moment the infant is able to achieve a voluntary prone position marks the beginning of the development of an infant's prone locomotion. As mentioned, there are typical sequences in which the infant’s prone locomotion develops (Figure 3.1). Figure 3.1 Typical developmental sequence of prone locomotion (Source: Adapted from Vereijken & Adolph, 1999) Crawling is distinguished by a homolateral pattern whereby the infant moves itself forward by stretching its arms in front of it, with its chest lifted off the ground, and in the process of lowering itself, the arms pull the body forward, resembling the Crawling on hands and knees (Creeping) Crawling forward with the belly dragging along the ground Immobility in a prone positionBSE201 STUDY UNIT 3 SU3-6 pattern of a combat crawl. Initial attempts in crawling usually does not involve the use of the lower limbs. The crawling pattern is usually present at about 6 months of age when stability is achieved. With time, belly crawling subsequently transitions to crawling on the hands and knees, also commonly referred to as creeping. Creeping is considered to be a more efficient form of locomotion as compared to crawling, as both the arms and legs are used for the propulsion of movement forward. Initial creeping patterns are characterised by movements of individual limbs, where the arms and legs are used in opposition of one another. As creeping involves stabilising the trunk in an elevated position above the ground as the limbs move forward, balance is considered to be an important individual constraint in the development of creeping (Vereijken & Adolph, 1999). The presence of balance as a constraint causes the infant to explore inter-limb movement patterns that allow for movement forward. Eventually, as the infant's proficiency in creeping increases, co-ordination between the limbs also improves to become more synchronised, and a clear contralateral pattern of movement can be observed. Identify and describe the individual, task and environmental constraints in the development of prone locomotion. 5.3 Development of Upright Locomotion Upright locomotion is only possible with the development of independent upright stance. Achievement of an upright standing posture marks a significant developmental milestone in the development of postural control, which is imperative for upright locomotion. 5.3.1 Standing Upright Independently In order to achieve upright stance, the development and control over lower limb and postural muscles are necessary for the ability to overcome gravitational forces. At about 9 or 10 months, with increased lower limb strength, infants are able to stand with the support of furniture for a period of time. In the next couple of months, the infant can be observed relying less heavily on the furniture for support, and can occasionally be seen maintaining independent upright stance for a brief moment without handheld support. By the age of about 11 to 12 months, the infant has gained increased upper limb muscular strength to be able to pull his/her weight to aBSE201 STUDY UNIT 3 SU3-7 standing position. During this time, infants who have just begun to stand take longer to use and adjust their postural muscles when thrown off balance. The initial independent stance of an infant can be characterised by a wide stance, with abducted feet to increase base of support, as well as arms held up for stability. 5.3.2 Characteristics of Early Walking Walking is the first upright form of bipedal locomotion in humans. Walking involves the shifting of one's weight from one foot to the other, with at least one foot maintaining contact with the ground at all times, with the aim of moving from one place to another. Before being able to walk independently, infants tend to display several skills in an upright posture that require the use of single limb support. As mentioned earlier, in early efforts to stand upright, the infant would use furniture to pull to stand, as well as to have it as a form of support. This often leads to the infant taking a few steps either forwards or sideways to 'cruise' in an upright position. The use of furniture by the infant helps to compensate for the much needed leg strength and postural control that is yet to be fully developed for independent walking. Because cruising resembles the temporal characteristics of walking, the practice of cruising has been suggested to help teach infants to walk. Furthermore, the practice of cruising would influence the development of the individual constraints such as lower limb strength, inter-limb co-ordination and increased postural control. Once infants begin to walk independently, their initial walking patterns are often described to be immature as they learn to cope with individual and environmental constraints of walking. Table 3.1 describes the characteristics of an infant's early walking gait together with its functional significance. In addition to the maturation of the central nervous system (CNS), other individual constraints such as muscular strength, musculoskeletal structure and postural control play a vital role in the development and maturation of independent walking. As walking involves single leg stance in at least 40% of the gait cycle, infants require sufficient balance control and leg strength to propel themselves forward on their own. This has led several motor developmentalists to identify the ability to keep balance and to support the body weight entirely on one leg as a control parameter for the transition to independent walking (Thelen, 1986; Whitall & Getchell, 1995). In addition, environmental factors such as parental encouragement and assistance during and prior to the transition have also been proposed to influence the development of independent walking.BSE201 STUDY UNIT 3 SU3-8 Table 3.1 Walking characteristics of new walkers and their functional significance Walking characteristic Functional significance Wide step width Due to poor postural control, infants widen their base of support and lower their centre of gravity to maintain balance as they move around Feet abducted Knees slightly flexed Arms lifted To assist with maintaining an upright posture Small steps Limit time in single leg stance, to maintain balance. Lack of propulsion due to poor muscular strength Non-synchronised and irregular stepping pattern Lack of lower limb control and constantly trying to regain balance 5.3.3 Typical Walking Gait Once walking is initiated, proficiency develops at an exponential rate. Stride length, speed of walking, and cadence increase; and movements show greater reproducibility as the walking pattern becomes more mature. For example, as balance improves, walking becomes more proficient as the base of support gradually narrows, so that the feet are placed within shoulder width apart. The average age at which most children achieve proficient/mature walking pattern is about 3 years of age. The typical proficient walking gait is characterised by: 1. Reflexive arm swing: As the child becomes more proficient, it loosens up the degrees of freedom, and the arms begin to swing rhythmically in opposition to the legs. 2. Narrow base of support: As balance improves, the base of support narrows to approximately shoulder width apart, and the feet are parallel to each other pointing forward. 3. Relaxed and elongated gait: As strength increases, stride length also increases.BSE201 STUDY UNIT 3 SU3-9 4. Minimal vertical lift: Increased control of ankle push off angle allows for propulsion forward rather than upwards. 5. Definite heel-toe contact: Initial flat foot contact of early walkers matures into a heel-toe pattern. The heel makes initial contact with the surface; as the body moves over the stance limb, the weight is transferred from the heel to the ball of the feet and toes. 5.3.4 Factors Affecting the Development of Walking In addition to some of the individual and environmental constraints mentioned earlier, other factors such as body weight and the use of infant walkers may also affect gait characteristics, as well as the onset of initial upright gait. Body composition Obesity in early childhood has often been associated with slower preferred walking speeds compared with their normal weight peers (Hills & Parker, 1991; 1992). The slower walking speed displayed in obese/overweight children is characterised by the longer single and double limb support phases, along with a shorter swing phase as compared with normal weight children (Hills & Parker, 1991; McGraw et al., 2000). The slower preferred walking speeds and longer periods of single and double limb support assist with the maintaining dynamic balance as a result of the poorer stability in children who are overweight or obese. Infant walkers Infant walkers are wheeled seats that provide infants with the ability to move around partially supported. Infant walkers are widely used by parents to encourage the child to move around the environment, as well as promote the onset of walking. Studies however, have reported that development of locomotion is affected adversely by the use of infant walkers (Crouchman, 1986; Garrett, McElroy & Staines, 2002; Siegel & Burton, 1999), with infants who use infant walkers achieving independent walking at a later age then non-users (Garrett et al., 2002; Siegel & Burton, 1999). Furthermore, Garrett and colleagues (2002) found strong associations between the amount of infant walker use and the extent of developmental delay, with 24 hours of infant walker use associated with a delay of walking alone by 3.3 days.BSE201 STUDY UNIT 3 SU3-10 Discuss the individual and environmental constraints that may limit the rate at which infant walking develops. You should now read: Haywood, Kathleen & Getchell, Nancy. (2009). Life Span Motor Development (5th ed.). Human Kinetics. pp.111-117. Gallahue, David, Ozman, John, & Goodway, Jacqueline. (2011). Understanding Motor Development: Infants, Children, Adolescents, Adults (7th ed.). McGraw-Hill. pp.145-147BSE201 STUDY UNIT 3 SU3-11 Chapter 6 Development of Manipulative Abilities Learning Outcomes By the end of this chapter, you should be able to: 1. Describe the developmental sequence of acquisition of manipulative abilities 2. Discuss the interaction between maturation of the motor, sensory and cognitive aspects and development of manipulative abilities 3. Describe the developmental sequence of acquisition in the development of handwriting Overview Similar to that of locomotor skills, the development of manipulative abilities advances through a predictable sequence of patterns. For successful manipulation of objects, it is crucial for the individual to develop the fundamental basics of reaching, grasping and release. The acquisition of these movement patterns is considered to be important developmental milestones in manipulative skills, allowing for further interaction with the environment. Furthermore, asymmetry is greatly pronounced in the upper limbs, with individuals developing strong dominance/preference for one arm above the other. Accordingly, with the fundamental manipulative abilities and the development of hand preference, children develop the use of a writing implement which is important for future academic performance.BSE201 STUDY UNIT 3 SU3-12 6.1 Reaching, Grasping and Releasing 6.1.1 What is Manipulation? Manipulation is the use of the hands to accomplish a specific task. Manipulation can be achieved by the use of both hands symmetrically or asymmetrically (bimanual), or the use of one hand (unimanual). Due to the musculoskeletal structure of the hand, hand movements are often categorised as intrinsic or extrinsic movements. Intrinsic movements are considered to be co-ordinated movements of the individual digits, providing for greater precision, which are controlled by the small muscles that lie within the hand. Extrinsic movements are controlled by the muscles that lie in the forearm, allowing for more gross movements of the fingers and wrist, and are considered to be the muscles that provide the major forces in the hand. 6.1.2 Reaching From a maturational perspective, the reaching behaviour does not appear until neuromotor connections are formed. As mentioned in Gesell's law of development, voluntary movements occur from a proximal-distal direction, in which control of movements begins from the trunk, followed by the upper arm, lower arm and lastly the fingers. Therefore, with regards to the development of reaching, once the infant is able to voluntarily control movements of the upper limb, he/she will make reaching attempts. At about the age of 4 months, infants will begin to reach for objects, a movement which is activated by one of the proximal shoulder or arm muscles. Initial reaching patterns tend to be performed bimanually with the use of both hands, and are slow and awkward, often producing unstable movements of the arm while extended in the direction of the object. As reach is visually initiated and not controlled, the infant frequently fails to reach the object, and would reattempt the reach without being able to correct the error during reach. At about 6 months of age, the reaching movement is both visually initiated and visually controlled, allowing for the infant to correct for errors throughout the reaching movement to ensure successful reach and contact of the object. These movements tend to be smoother, more direct, and have more stable reaching path, with some infants performing more unimanual reaching movements. As infant perception improves, infants begin to orientate and pre-shape their motor responses according to the visually perceived physical characteristics of the object at about 7-8 months of age (Corbetta et al., 2000; Fagard, 2000; von Hofsten & Fazel-Zandy, 1984). The development of reaching in infants has often been studied from a dynamical system perspective, according to that of Newell's constraint-led model. Studies haveBSE201 STUDY UNIT 3 SU3-13 identified several individual constraints, such as the level of postural control (Fallang, Saugstad, & Hadders-Algra, 2000; Rochat & Goubet, 1995), as well as environmental constraints, such as object size and rigidity (Rocha, Silva, & Tudella, 2006), and the influence of gravity (Rochat, 1992; Savelsbergh & Van der Kamp, 1994; Out, Van Soest, Savelsbergh, & Hopkins, 1998). For example, as there are drastic changes in body proportion and mass during the first year, this individual constraint greatly influences the development of postural control and the initiation of reach. Reaching requires a certain amount of minimal force to lift the arm to overcome the gravitational torque that is imposed on the reaching arm. Savelsbergh & Van der Kamp (1994) in investigating the interaction of individual and environmental constraints on reaching behaviour found that infants performed more reaches in the vertical position as opposed to the supine position. It was suggested that in the vertical position, infants require less necessary force to overcome gravitational torque as compared to that in the supine position. 6.1.3 Grasping The action of grasping can be observed early during prenatal development and in new born infants. These initial grasping actions are entirely reflexive in nature (palmar grasp) until further maturation of the cerebral cortex. Voluntary grasping actions are first observed at about 4 months of age, together with initial voluntary reaching actions. The different phases of grasping development were first described by Halverson in 1931. Halverson studied infant grasping behaviour of a 1 inch cube from 16 to 52 weeks of age, and described infant development of grasping in 10 different phases (as summarised in Table 3.2). At the onset of voluntary reaching and grasping, the infant's movements are often poorly adjusted to the physical characteristics of the object. As the infant reaches for the object, it is unable to adjust the shape of its hand to match the size or orientation of the object, but rather, it would repeatedly open and close its hand, without being able to make contact with the object (Corbetta, Thelen, & Johnson, 2000; Fagard, 2000; Halverson, 1931). Once the infant is able to make contact with the object, it would attempt to grasp the object with the entire hand, squeezing the object against the palm. Subsequently, as the infant develops coordinated control of the fingers, the infant at about 7 months of age, is able to use the thumb and the fingers to grasp the object. As individual control and co-ordination of the individual fingers continue to develop, the infant would display the use of the forefinger for grasping the object, with fewer fingers in contact with the object. Finally, grasping movements become much more refined, such that the infant is able to use the pincer grip, by holding the object with its thumb and index finger.BSE201 STUDY UNIT 3 SU3-14 Similar to that of reaching, the development of grasping has also been explained through the interaction of individual, environment and task constraints. Newell and colleagues (1989) examined the effects of using various sizes of objects (1 cube and 3 cups of different diameters) on the type of grip used by infants of 4-8 months of age. They found that the grip used depended on the size and shape of the object, with the use of precision grips with the smallest cup in younger infants as compared to that described by Halverson (1931). Similarly, object-to-hand-size ratio was found to be a factor that related to the use of unimanual or bimanual grasp in young children, thereby emphasising the role that task constraints play on grasping behaviour (Newell, Scully, Tenenbaum, & Hardiman, 1989). Table 3.2 Halverson's 10 stages of grasping development in infants aged 16-52 weeks old Type of grasp Age (weeks) Grasping characteristic No contact 16 Failure to make contact Contact only 20 Contact with object without grasp Primitive squeeze 20 Object is obtained by squeezing the object against the body or opposite hand Squeeze grasp 24 From a lateral approach, fingers close around the object, pressing it against the palm of the hand Hand grasp 28 Hand is bridged over the object; fingers and thumb (with the thumb parallel to the fingers) press the object against the palm of the hand Palm grasp 28 Hand is bridged over the object, with the fingers and thumb curling around the object Superior-palm grasp 32 The thumb and fingers apply pressure on the object Inferior-forefinger grasp 32 Fingers (pointing medially) and thump wrap around the object, maintaining the object in the palm area Forefinger grasp 52 First three fingers oppose the thumb in the grasp with the hand on a supported surface Superiorforefinger grasp 52 Fingers oppose the thumb without a supportive surface (Source: Adapted from Halverson, 1931)BSE201 STUDY UNIT 3 SU3-15 Describe the importance of postural control as an individual constraint on the development of reaching and grasping. Explain how task constraints might alter reaching and grasping behaviour in infants. 6.1.4 Releasing The ability of an infant to release an object voluntarily takes longer to develop as compared to reaching and grasping. Around 4-5 months of age, the infant has yet to develop voluntary release of an object. Release of an object during this period is often accidental or occurs involuntarily in movement. At about 6 months, release of an object can be observed during mouthing and bimanual play, whereby the infant having placed the object in the mouth or with both hands, would release one hand with the object being stabilised either in the mouth or other hand. Through constant interaction with the environment, the infant gains greater control of the flexor muscles of the fingers, allowing for the release of the object in the hand by about the age of 7 months. At the age of 10-11 months, the infant displays purposeful release of an object during play, using full finger and thumb extension. By 1 year of age, the infant demonstrates greater proficiency in object release, where it is able to practise precision release by stacking items on top of one another. You should now read: Haywood, Kathleen & Getchell, Nancy. (2009). Life Span Motor Development (5th ed.). Human Kinetics. pp.169-177. Gallahue, David, Ozman, John, & Goodway, Jacqueline. (2011). Understanding Motor Development: Infants, Children, Adolescents, Adults (7th ed.). McGraw-Hill. pp.147-150.BSE201 STUDY UNIT 3 SU3-16 6.2 Development of Handedness Handedness is the preferential use of one hand over the other. The development of handedness in infants has been extensively studied. Although it has been commonly suggested that handedness is not clearly established until early childhood, there is growing evidence to propose that infants develop a hand preference as early as grasping emerges, at the age of about 7-13 months (Fagard & Lockman, 2005; Michel, Tyler, Ferre, & Sheu, 2006). As the majority of the adult population are strongly right handed (~90%), epidemiological literature of the 1960s to 1980s has often associated left handedness with health problems such as atopic diseases, depression, learning disabilities and delinquency (Ramadhani et al., 2006; Satz et al., 1985). 6.2.1 Theories of Handedness There are several theories to explain the development of handedness in human individuals which have evolved from both the nature and nurture perspectives. Theories of handedness suggest that the development of a preference for either hand may be due to: (1) genetics, (2) brain pathology, and (3) parental handedness. The genetic model was proposed by Annett (1985), whereby handedness was determined by one gene with two alleles (dominant or recessive). The dominant Right Shift allele (RS+) selects for right handedness, whereas the recessive allele (RS-) selects for both right and left handedness. Annett theorised that individuals with both alleles (RS+ RS-) had a cognitive advantage as compared to individuals who are strong right-handers (RS+ RS+) as cognitive deficits in spatial processing were found in strong right-handers (Annett, 1992). In support of a genetic perspective, research studying prenatal and early foetal development have observed that foetuses develop a preference for their right side as early as 15 weeks in gestational age (Hepper, Shahidullah, & White, 1991). Furthermore, increased maturation of the left hemisphere (Chi, Dooling, & Gilles, 1977) and advanced maturation of the left cortical spinal tract (Liu et al., 2010) have been suggested to be responsible for the asymmetrical development of spontaneous early movements. In addition to the genetic model, left handedness has also been suggested to be a result of brain pathology. Bakan and colleagues (1973) proposed that a shift from left-hemisphere dominance to right-hemisphere dominance could be due to some minor lesions in the brain of the left hemisphere either during pregnancy or the birthing process. This proposed theory however has been found to only account for a small proportion of individuals who are left-handers (Satz et al., 1985). In addition, the brain pathology model is further supported by research that has found anBSE201 STUDY UNIT 3 SU3-17 increased number of left-handedness in children who had severe bacterial meningitis (Ramadhani et al., 2006), females who experienced early neurologic insult (Miller et al., 2005), and infants who experienced birth asphyxia (Fox, 1985). Despite Annett's and Bakan's theory supporting the advantages present in righthanders, McManus (2002) suggests that being left-handed also has a cognitive advantage. In support of this, Benbow (1986) and Halpern et al. (1998) found lefthanders to have higher scores on verbal reasoning tests and are more gifted. In contrast, mixed-handedness (individuals with no hand preference) are considered to be most disadvantaged compared to right or left-handers. Orton (1937) first proposed that mixed-handedness and poor laterality in handedness were associated to learning disabilities in children. Subsequently, this notion was supported by Crow and colleagues (1998) emphasising the importance of laterality for language and higher cognitive functions to develop. Much more recent large-scale studies have also found supporting evidence that mixed-handers may be less cognitively competent (Corballis et al., 2008; Peters, Reimer, & Manning, 2006). Corballis and colleagues (2008) compared the intelligence quotient (IQ) of left-handers, righthanders and mixed-handers. They found that the IQ was similar between left and right-handers, with mixed-handers attaining lower IQ scores and having poorer performance on the arithmetic, memory, and reasoning items. Lastly, strong evidence has been found for parental handedness on development of handedness in children. In a study which examined the relationship between development of handedness and parental handedness, Falek (1959) observed that left handed fathers discouraged the child's use of the left hand in manipulative tasks, thereby producing children who developed right hand dominance. Similarly, due to the parents’ bias towards hand preference, opportunities and encouragement for learning would subsequently be lateralised to that of their parents (Williams & Scott, 1953). Furthermore, culture specific expectations may also influence the child's hand preference, in which tools which are used daily to carry out tasks are dominantly created for right-handers (Fagard & Dahmen, 2004).BSE201 STUDY UNIT 3 SU3-18 6.3 Development of Handwriting Development of handwriting is one of the few fine motor skills that have received attention in early childhood motor development. The development of handwriting ability is not only able to improve a child's self-esteem, but is also crucial for academic success during school-age years. It takes many years for a child to develop a mature grasp in holding a writing implement to allow for fine and controlled writing or drawing. 6.3.1 Holding a Writing Implement The supinate grasp At about 1 1/2 years old when the child grasps onto a writing implement, it usually involves the entire hand. The child would hold the implement with a supinate grasp (Rosenbloom & Horton, 1997), in which all four fingers and the thumb wrap around the pencil. In attempts to draw, movement mainly occurs from the shoulder, with little or no movements initiated at the elbow and wrist. Initial drawing attempts are uncontrolled, with random markings on a paper and spontaneous scribbling. The pronate grasp The pronate grasp soon replaces the supinate grasp, in which the four fingers and thumb wrap around the pencil with the wrist in a pronate position (palm facing down (Rosenbloom & Horton, 1997). This occurs at about 2-3 years of age. With the pronate grasp, the child begins to gain control of the lower arm, initiating drawing movements with the elbow and shoulder. At this stage, the child has increased control of pencil movements, being capable of drawing vertical and horizontal lines, and would imitate drawing a circle. Upon developing a pronate grasp, the child would begin to refine the position of its fingers and thumb around the pencil to increase control of the pencil while drawing or writing. For example, the child would begin to move the grasp closer to the tip of the pencil with increased stabilisation of the pencil by the thumb and fingers. Basic tripod By the age of 4 years old, children often progress to a static tripod grasp, with the four fingertips and tip of the thumb in contact with the holding on to the pencil, and the pencil being supported by the webbing of the thumb and index finger (Rosenbloom & Horton, 1997). Writing movements are now initiated at the wrist, with the hand moving as a unit, and the forearm resting on the table. During this time, the child continues to improve writing technique, characterised by small flexion and extension movement of the hand joints.BSE201 STUDY UNIT 3 SU3-19 Dynamic tripod The dynamic tripod grasp is usually achieved by 7 years of age (Rosenbloom & Horton, 1997). The tripod grasp is characterised by the pencil being stabilised on the third digit, with the tip of the index finger and the thumb stabilising the pen, and the remaining fingers flexed. Writing is controlled by movements of the digits of the tripod and wrist, with the forearm resting on the table. In the dynamic tripod grasp, the middle, index finger and thumb function together to create controlled and highly coordinated movements, thereby improving the quality of handwriting. Discuss how maturation and the interaction of individual, task and environmental constraints contribute to the development of handwriting.BSE201 STUDY UNIT 3 SU3-20 Quiz 1. At about what age do children achieve proficient walking? a) 2 b) 3 c) 4 d) 5 2. Which statement about early walking characteristics is not true? a) Feet adducted to widen base of support b) Small steps to limit time in single leg stance c) Arms up to assist in maintaining upright posture d) Flexed knees to lower centre of gravity 3. Which of the following acts as a major control parameter controlling for the transition of crawling to independent walking? a) Practice b) Balance c) Vision d) Co-ordination 4. During the first year, reaching was most often observed when placed in a/an __________ position. a) supine b) recline c) upright d) pronate 5. By what age does the child develop a basic tripod grasp for writing? a) 2 b) 3 c) 4 d) 5BSE201 STUDY UNIT 3 SU3-21 Summary During the first few years of life, development of rudimentary movements proceeds according to a predictable sequence, although the rate of acquisition of the various milestones may vary considerably from child to child. As discussed throughout Chapter 5, achievements of locomotive behaviour are not only a result of neurological maturation, but also a function of inter-relationships between constraints of the individual, environment and task. With the development of postural control, the infant is able to position himself appropriately to locomote, which marks the beginning of a sequence of postural changes for the acquisition of upright locomotion. Although initial crawling patterns are awkward and inefficient, increased muscular strength, inter-limb coordination and postural control allow for the rapid transition from crawling to creeping, creeping to cruising, and cruising to independent walking. The development of manipulative skills is crucial for the infant to be able to learn through interaction with his/her environment. Within the first 2 years of life, the infant is able to reach, grasp, release and manipulate an object, for example a writing implement. Similar to the development of locomotor skills, the attainment of manipulative abilities also varies from individual to individual. For example, the development of handedness is influenced by both genetic and environmental factors. In the same way, the rates of development of reaching and grasping are also affected by the interaction of individual, task and environmental constraints.BSE201 STUDY UNIT 3 SU3-22 References Annett, M. (1985). Left, right, hand and brain: The right shift theory. London: Lawrence Earlbaum. Annett, M. (1992). Spatial ability in subgroups of left- and right-handers. British Journal of Psychology, 83, 492-515. Bakan, P., Dibb, G., & Reed, P. (1973). Handedness and birth stress. Neuropsychologia, 11, 363-66. Barela, J.A., Jeka, J.J., & Clark, J.E. (1999). The use of somatosensory information during the acquisition of independent upright stance. Infant Behaviour and Development, 22, 87-102. Benbow, C.P. (1986). Physiological correlates of extreme intellectual precocity. Neuropsychologia, 24, 719-725. Bernstein N. (1967). Co-ordination and regulation of movements. New York, NY: Pergamon Press Inc. Chi, J.G., Dooling, E.C., & Gilles, F.H. (1977). Left-right asymmetries of the temporal speech areas of the human fetus. Archives of Neurology, 34, 346-348. Corballis, M.C, Hattie, J., & Fletcher, R. (2008). Handedness and intellectual achievement: An even-handed look. Neuropsychologia, 26, 374-378. Corbetta, D., Thelen, E., & Johnson, K. (2000). Motor constraints on the development of perception-action matching in infant reaching. Infant Behavior and Development, 23, 351–374. Crouchman, M. (1986). The effects of baby walkers on early locomotor development. Developmental Medicine and Child Neurology, 28, 757-761. Crow, T.J., Crow, L.R., Done, D.J., & Leask, S. (1998). Relative hand skill predicts academic ability: Global deficits at the point of hemispheric indecision. Neuropsychologia, 36, 1275-1282. Fagard, J. (2000). Linked proximal and distal changes in the reaching behaviour of 5- to 12-month old human infants grasping objects of different sizes. Infant Behavior and Development, 23(3-4), 317-329.BSE201 STUDY UNIT 3 SU3-23 Fagard, J., & Dahmen, R. (2004). Cultural influences on the development of lateral preferences: A comparison between French and Tunisian children. Laterality: Asymmetries of Body, Brain and Cognition, 9, 67-78. Fagard, J., & Lockman, J.J. (2005). The effect of task constraints on infants’ (bi)manual strategy for grasping and exploring objects. Infant Behavior and Development, 28, 305- 315. Falek, A. (1959). Handedness, a family study. The American Journal of Human Genetics, 11, 52-62. Fallang, B., Saugstad, O.D., & Hadders-Algra, M. (2000). Goal directed reaching and postural control in supine position in healthy infants. Behavioural Brain Research, 115, 9-18. Forssberg, H., & Hirschfeld, H. (1994). 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Archives of Physical Medicine and Rehabilitation, 72, 403-407. Hills, A.P., & Parker, A.W. (1992). Locomotor characteristics of obese children. Child: Care, Health and Development, 18(1), 29-34. Lee, D.N., & Aronson, E. (1974). Visual proprioceptive control of standing in human infants. Perception and Psychophysics, 15(3), 529-532. Liu, Y. et al. (2010). Structural asymmetries in motor and language networks in a population of healthy preterm neonates at term equivalent age: A diffusion tensor imaging and probabilistic tractography study. Neuroimage, 51, 783-788. Massion, J. (1992). Movement, posture and equilibrium: Interaction and coordination. Progress in Neurobiology, 38, 35-56. McCollum, G., & Leen, T.K. (1989). Form and exploration of mechanical stability limits in erect stance. Journal of Motor Behavior, 21, 225-244. McGraw, M.B. (1943). The neuromuscular maturation of the human infant. New York: Columbia University Press. McGraw, B., McClenaghan, B.A., Williams, H.G., Dickerson, J., & Ward, D.S. (2000). Gait and postural stability in obese and non-obese pre-pubertal boys. Archives of Physical Medicine and Rehabilitation, 81, 484-489. McManus, I.C. (2002). Right hand, left hand: The origins of asymmetry in brains, bodies, atoms and cultures. London: Weidenfeld and Nicolson.BSE201 STUDY UNIT 3 SU3-25 Metcalfe, J.S., & Clark, J.E. (2000). Sensory information affords exploration of posture in newly walking infants and toddlers. Infant Behavior and Development, 23, 391-405. Michel, G.F., Tyler, A.N., Ferre, C., & Sheu, C.F. (2006). The manifestation of infant hand-use preferences when reaching for objects during the seven- to thirteen-month age period. Developmental Psychobiology, 48, 436-443. Miller, J.W., Jayadev, S., Dodrill, C.B., & Ojemann, G.A. (2005). Gender differences in handedness and speech lateralisation related to early neurologic insults. Neurology, 65, 1974-1975. Newell, K.M., Scully, D.M., McDonald, P.V., & Baillargeon, R. (1989). Task constraints and infant grip configuration. Developmental Psychobiology, 22, 817-832. Newell, K.M., Scully, D.M., Tenenbaum, F., & Hardiman, S. (1989). Body scale and the development of prehension. Developmental Psychobiology, 22, 1-13. Orton, S.J. (1937). Reading, writing and speech problems in children. New York: Norton. Owen, B.M., & Lee, D.N. (1986). Establishing a frame of reference for action. In M.G. Wade and H.T.A. Whiting (Eds.), Motor Development in Children: Aspects of Coordination and Control. Dordrecht: Martinus Nijhoff. Out, L., Van Soest, A.J., Savelsbergh, G.J.P., & Hopkins, B. (1998). The effect of posture on early reaching movements. Journal of Motor Behavior, 30, 260-272. Peters, M., Reimers, S., & Manning, J.T. (2006). Hand preference for writing and associations with selected demographic and behavioural variables in 255,100 subjects: The BBC internet study. Brain and Cognition, 62, 177-189. Ramadhani, M., Koomen, I., Grobbee, D., van Donselaar, C., van Furth, A.M., & Uiterwaal, C. (2006). Increased occurrence of left-handedness after severe childhood bacterial meningitis: Support for the pathological left-handedness hypothesis. Neuropsychologia, 44, 2526-2532. Rocha, N.A.C.F., Silva, F.P.S., & Tudella, E. (2006). The impact of object size and rigidity on infant reaching. Infant Behavior & Development, 29, 251-261. Rochat, P. (1992). Self-sitting and reaching in 5–8 month-old infants: Impact of posture and its development on early eye-hand coordination. Journal of Motor Behavior, 24, 210-220.BSE201 STUDY UNIT 3 SU3-26 Rochat, P., & Goubet, N. (1995). Development of sitting and reaching in 5 to 6- month-old-infants. Infant Behavior and Development, 18, 53-68. Roncesvalles, M.N., Woollacott, M.H., Brown, N., & Jensen, J.L. (2004). An emerging postural response: Is control of the hip possible in the newly walking child? Journal of Motor Behavior, 36, 147-159. Rosenbloom, L., & Horton, M.E. (1997). The maturation of fine prehension in young children. Developmental Medicine and Child Neurology, 13, 38. Satz, P., Orsini, D.L., Saslow, E., & Henry, R. (1985). The pathological lefthandedness syndrome. Brain and Cognition, 4, 27-46. Savelsbergh, G.J.P., & Van der Kamp, J. (1994). The effect of body orientation to gravity on early infant reaching. Journal of Experimental Child Psychology, 58, 510-528. Siegel, A.C., & Burton, R.V. (1999). Effects of baby walkers on motor and mental development in human infants. Journal of Developmental and Behavioral Pediatrics, 20(5), 355-361. Thelen, E. (1985). Developmental origins of motor coordination: Leg movements in human infants. Developmental Psychobiology, 18, 1-22. Thelen, E. (1986). Development of coordinated movement: Implications for early human development. In M.G. Wade and H.T.A. Whiting (Eds.), Motor Development in Children: Aspects of Coordination and Control. Dordrecht: Martinus Nijhoff. Vereijken, B., & Adolph, K.E. (1999). Transitions in the development of locomotion. In G.J.P. Savelsbergh, H.L.J. van der Maas, & P.C.L. van Geert (Eds.), Non-linear analyses of developmental processes. Amsterdam: Elsevier. von Hofsten, C., & Fazel-Zandy, S. (1984). Development of visually guided hand orientation in reaching. Journal of Experimental Child Psychology, 38, 208-219. Whitall, J., & Getchell, N. (1995). From walking to running: Applying a dynamical systems approach to the development of locomotor skills. Child Development, 66, 1541-1553. Williams, J.R., & Scott, R.B. (1953). Growth and development of Negro infants: IV. Motor development and its relationship to child-rearing practices in two groups of Negro infants. Child Development, 24, 103-121.BSE201 STUDY UNIT 3 SU3-27 Witherington, D.C., Von Hofsten, C., Rosander, K., Robinette, A., Woollacott, M.H., & Bertenthal, B.I. (2002). The development of anticipatory postural adjustments in infancy. Infancy, 3, 495-517. Woollacott, M.H., Debu, B., & Mowatt, M. (1987). Neuromuscular control of posture in the infant and child: Is vision dominant? Journal of Motor Behavior, 19, 167-186.BSE201 STUDY UNIT 3 SU3-28 Solutions or Suggested Answers 1. b) 3 2. a) Feet adducted to widen base of support 3. b) Balance 4. c) upright 5. c) 4STUDY UNIT 4 DEVELOPMENT OF FUNDAMENTAL MOVEMENT SKILLSBSE201 STUDY UNIT 4 SU4-2 Chapter 7 Childhood Growth and Development Learning Outcomes By the end of this chapter, you should be able to: 1. describe the physical changes that occur in early childhood 2. discuss the gender differences in physique during childhood 3. explain how various factors may influence the growth process 4. describe the changes occurring in the brain 5. identify the typical cognitive development characteristics of a child Overview Childhood is a period of growth, in which the child grows both physically and cognitively. Physical growth has important implications for the development of movement skills in childhood. The development of the musculoskeletal system and the changes in body proportions allow for increased postural control and performance of manipulative tasks while standing upright. Similarly, changes in cognitive function are also observed during childhood, whereby children are able to plan and perform co-ordinated movement patterns, as well as begin to display increased working memory capabilities.BSE201 STUDY UNIT 4 SU4-3 7.1 Physical Growth Physical growth is a process whereby there are increases in structural size, marked by increases in height, weight and muscle mass. Similar to the developmental milestones, growth occurs in a predictable sequence throughout childhood, although individual variability exists. The overall body growth pattern resembles an S-shaped curve (Sigmoid curve), whereby growth is characterised by: (1) rapid growth immediately after birth, (2) steady growth during childhood, (3) rapid growth during adolescence, and (4) levelling off during adulthood. Childhood is often divided into 2 periods, early childhood and later childhood. The early childhood period is from 2 to 6 years of age, whereas, the later childhood period is from 6 to 10 years of age 7.1.1 Growth Early childhood growth rate slows in comparison to that of the first 2 years of infancy, which was marked by rapid growth in length and weight, and changes in body proportions. Annual height gain from early childhood is about 5 cm per year, with weight gains about 2.3 kg per year. During the first 3 years of early childhood, at about the age of 5, the child would have doubled his/her weight from 2 years of age. During this period of growth, minimal differences in physique is observed between genders, with boys and girls growing at similar rates, although boys may be slightly taller and heavier than their female counterparts. In addition, by the end of later childhood, despite similar growth rates between genders, boys tend to have greater limb length and standing height than girls. Musculoskeletal growth is also similar between both boys and girls, with steady increases in muscle and bone mass, and a steady decrease of adipose tissue throughout childhood. Body proportions also change drastically during early childhood, with different parts of the body growing at varying rates. In a new born, the head constitutes onefourth of the total height, but one-sixth of the total height of a 6-year-old child, resembling that of older children. Similarly, the centre of mass moves down from the middle torso at birth to mid pelvis area by the end of the early childhood period. These changes in body proportions are mainly attributed to leg growth in both genders. As for body girth, the chest gradually grows to become larger than the abdomen, with less protrusion of the stomach as observed in new-borns. The period of early and later childhood is also a time of skeletal growth and change, marked by rapid bone ossification. Bone ossification is a process whereby bone is formed from connective tissue. This period in which bone ossification occurs is a sensitive period for children, as malnutrition could be detrimental to growth.BSE201 STUDY UNIT 4 SU4-4 7.1.2 Factors Affecting Growth Nutrition Nutrition is a factor that affects development at all stages of life. As mentioned in Unit 2, nutritional status of the mother plays an important role in the growth and development of her foetus. Similarly, during childhood, diets of poor nutritional quality or malnutrition can be detrimental to the growth of the child. It is well evidenced in the literature that dietary deficiencies can stunt growth, as well as lead to retardation of the child. Furthermore, the period at which malnutrition occurs also determines the severity and permanency of the effects on development. Insufficient amounts of iron, calcium, vitamin C, and vitamin A are the most common diet deficiencies of the early childhood years. These diet deficiencies may contribute to the incidence of certain diseases that affect growth. For example, rickets which is caused by a deficiency in vitamin D results in softening and deformity of the bones. A lack of vitamin C might also result in energy loss and joint pain, a disease known as scurvy. In addition, under-nutrition in childhood was also suggested to be a risk factor for high glucose concentrations, blood pressure and harmful lipid profiles in adulthood (Victora et al., 2008). Furthermore, studies examining the impact of chronic malnutrition in early childhood from developing countries, found that childhood stunting was linked with shorter adult stature, reduced lean body mass, and diminished intellectual functioning (Victora et al., 2008). On the contrary, excessive dietary intake can also affect growth development of children. Childhood obesity is becoming a prevalent problem in today's society, with obesity developing as a result of overconsumption of calorie-dense foods, such as refined starches and sugars. There can be harmful consequences of childhood obesity, which can affect every organ system, resulting in diseases such as type-2 diabetes, fatty liver disease and asthma (Daniels et al., 2009; Han, Lawlor, & Kimm, 2010; Reilly, 2005). Physical activity Given that muscle growth is one of the aspects of physical growth, physical activity is considered to be the main contributing factor to the maintenance and development of muscle mass in childhood. Physical activity promotes movements of the body, thereby allowing hypertrophy of the muscle tissues. On the other hand, the lack of physical activity would also result in atrophy of the muscles tissue. Therefore, a lifestyle that promotes physical activity, would also play a role in muscleBSE201 STUDY UNIT 4 SU4-5 development. Furthermore, an active lifestyle would decrease the possibility of childhood obesity. Physical activity despite its advantages, could also result in negative outcomes when done in excess. There is a growing concern on the impact that excessive and intensive training might have on the development during childhood. Several studies have found that excess training in young athletes affects somatic growth, and skeletal and pubertal maturation (Claessens et al., 1992; Erladson et al., 2008; Georgopoulos et al., 2010). Illness Although the standard childhood illnesses (chicken pox, measles and colds) tend to have limited impact on the normal growth of a child, the interaction of malnutrition and illness of the child puts the child at greater risk of growth deficits. In childhood development, often a self-regulatory growth process allows for a child to 'catch-up' with his/her peers, however, depending on the extent, duration, severity and timing of the illness, it may result in major deviations which cannot be caught up. 7.2 Cognitive Development Cognitive development is the study of thinking and reasoning of a child, and how children become more efficient and effective in their understanding of the environment (Oakley, 2004). In cognitive development, it is strongly suggested that maturation of the neural structures determines the onset and rate of cognitive development, and experience only begins to contribute to development once the biological structures are ready. At birth, the brain is about 25% of its adult weight. By the age of 3, the brain is about 75% of its adult brain, and almost 90% by the age of 6. This rapid growth in brain weight during the early childhood period reflects increases in neuron size, number of synapses, and an increase in glia and myelin. The spinal cord and lower brain structures are almost fully developed at birth, as compared to the higher brain structures. The ongoing development of the sensory and motor systems in infants, as evidenced by goal-directed reaching movements, reflect the maturation of the cerebral cortex, with the cerebral cortex considered to be completely developed at the age of 4 (Gallahue, Ozmun, & Goodway, 2011). Myelination, which is the development of fat cells around the axon of the outgoing neuron, contributes to the speedy transmission of nerve impulses throughout the nervous system. Throughout childhood, increased myelination allows for rapid andBSE201 STUDY UNIT 4 SU4-6 frequent firing of nerve impulses throughout the nervous system to perform rapid movements and postural adjustments. Although it is well established that neural development of the brain and cognitive development mature concurrently during childhood, little is known about the direct relationship between neural and cognitive development. During the childhood years, it is observed that children are eager to learn new things, and often ask "why". Although they are not capable of abstract thinking, they are able to understand concrete examples when used (Gallahue et al., 2011). Recent research that has implemented the use of functional magnetic resonance imaging (fMRI) and diffusion tension imaging (DTI) has been able to study the biological substrates of cognitive development (Casey, Galvan, & Hare, 2005). From these studies, researchers have identified brain regions that support sensory and motor function mature earliest, whereas higher order association areas, such as the prefrontal cortex which is involved in working memory, response inhibition, and attention allocation mature later (Gogtay et al., 2004; Sowell et al., 2004). For example, Luciana and Nelson (1998) examined the performance of normal children, aged 4 to 8 years on prefrontal cortex functions, and found that working memory emerges at around the age of 4 and improves substantially between 5 and 7 years of age. As neurological development is occurring at a rapid rate during early childhood, any illnesses or malnutrition during this period can be extremely detrimental to the growth of the brain. As mentioned earlier, malnutrition in early childhood could lead to retardation and diminished intellectual functioning of the child. Furthermore, any injury to the left hemisphere, may lead to deficits in language development, as language centres of the brain are located in the left hemisphere. You should now read Gallahue, David, Ozman, John, & Goodway, Jacqueline. (2011). Understanding Motor Development: Infants, Children, Adolescents, Adults (7th ed.). McGraw-Hill. Chapter 10.BSE201 STUDY UNIT 4 SU4-7 Chapter 8 Fundamental Movement Skills Learning Outcomes By the end of this chapter, you should be able to: 1. categorise the proficiency of a child's movement into developmental stages 2. determine the proficiency of a variety of fundamental locomotion skills 3. design an observational assessment checklist to evaluate proficiency of movement 4. discuss the maturation process in the development of object control skills 5. discuss the importance of perception-action coupling in the development of object control skills 6. explain how several factors may influence the development of fundamental movement skills Overview Fundamental movement skills are foundational movements that allow for the development of more complex and specialised skills in the future, allowing for participation in various games and sport. There are three main classifications of fundamental movement skills, namely stability, locomotion, and object control. In this chapter we would focus on the development of fundamental locomotion skills and object control skills. In addition, although most fundamental movement skills progress from one level of proficiency to the next, the acquisition of proficient movement of the skill is largely dependent on experience other than maturation. Environmental constraints such as practice, and social and cultural factors will influence the rate at which a child progresses through the stages of development to successfully acquire proficient movement.BSE201 STUDY UNIT 4 SU4-8 8.1 Fundamental Locomotion Skills Locomotion is the act of moving from one place to another. For young children, the ability to move around effectively and efficiently is important for them in exploring and learning through their environment. Examples of fundamental locomotor skills are walking, running, jumping and hopping. These fundamental locomotor skills act as a building block for the development of more complex skills such as hurdling and high jumping, and the participation of sport such as athletics and soccer. 8.1.1 Running Running is a central skill that is required for children to participate in many moderate to vigorous sporting activities, such as soccer, tennis, basketball and athletics. It is a complex activity and requires a high degree of coordination between the hip, knees and ankles to propel and support the body of mass forward. It is distinguished from walking by a distinct flight phase where neither foot is in contact with the ground. The running gait cycle begins at initial contact when one foot comes into contact with the ground and ends when the same foot contacts the ground again (Whittle, 2007). As speed increases from walking to running, there are no periods when both feet are in contact with the ground, along with a reduction in the time spent in stance with a resultant increase in swing phase time during the gait cycle (Dicharry, 2010; Novacheck, 1998). The change in temporospatial patterns from walking to running reflects an increased demand for inter-limb coordination to provide improved balance during single limb stance (Whitall & Caldwell, 1992). The increase in speed from walking to running is also further characterised by an increase in stride length and stride rate (Ounpuu, 1994). To achieve a faster speed of running, there is a need for increased power generation through the lower limb muscles for forward propulsion, resulting in greater lower limb joint excursions (Dugan & Bhat, 2005; Mann & Hagy, 1980). Developmental sequence for running Once children start to walk, about 6-7 months after, around 2 years of age, they would soon attempt to run. Early running attempts are not dependent on a mature walking pattern, and therefore many young children attempt to run before having achieved mature walking. The earliest attempts by infants to run resemble fast walking, with one foot in contact with the ground at any one point in time.BSE201 STUDY UNIT 4 SU4-9 The moment a flight phase is present, the child is considered to display an initial running pattern. The following describes the initial stage of running: Arm action  Arms are flexed in a high guard position  Tendency to swing the arms across the body's midline Leg action  Incomplete extension of the push off leg  The swinging leg rotates outwards from the hip (slight abduction of the hip)  Foot eversion of the swinging foot Temporospatial characteristics  Minimal flight phase  Inconsistent stride lengths  Wide stride width As the child continues to develop greater lower limb strength, dynamic balance and co-ordination, their running gait becomes slightly more proficient. The following describes the elementary stage of running: Arm action  Arm swing begins to increase, with lesser swing on the backswing Leg action  Greater knee extension of the push off leg  The swinging moves forward at a greater speed instead of swinging outward  The swinging foot tends to cross the midline of the body Temporospatial characteristics  Increased flight phase  Increased stride length  Narrowing of stride widthBSE201 STUDY UNIT 4 SU4-10 Finally, at about 5 years of age, children tend to display a proficient/mature running pattern, as described below: Arm action  Arms bent at ~90° angle  Arms swing in a sagittal plane, in opposition to the legs Leg action  Complete extension of the push off leg  Recovery thigh is parallel to the ground, with flexion of the hip and knee during the forward swing  Forward movement of the swing leg is mainly in the sagittal plane Temporospatial characteristics  Definite flight phase  Maximum stride length  Minimal stride width 8.1.2 Jumping Typically, children attempt jumping at about the age of 2. The skill of jumping involves projecting one's body into the air by power generated from either one or both legs, and landing with one or both feet. Jumping that involves a two-footed takeoff and landing, consists of the vertical jump and the horizontal standing broad jump. Other variations of jumping which involve one legged takeoff and landing are hopping, skipping and leaping. The vertical jump is characterised by an upward thrust of the body, whereas the horizontal jump is characterised by an upward and forward propulsion of the body. Irrespective of whether it is a vertical or horizontal jump, both have similar phases, including a preparatory, a takeoff, and a landing phase. In this chapter we would focus on the developmental sequence of the horizontal jump. Developmental sequence for horizontal jumping The very first initial observations of young children attempting to jump have been reported to be a jumping down from one foot to the other. Subsequently, they start to jump off the floor with both feet.BSE201 STUDY UNIT 4 SU4-11 The following describes the initial stage of horizontal jumping: Preparatory phase  Limited arm swing  Arms do not assist in initiating the jump  Trunk remains in an upright position  Limited hip, knee and ankle flexion in preparatory crouch Takeoff phase  Limited arm swing  Arms may move sideways or backwards during flight for control of balance  Trunk remains in a vertical position  Difficulty in using both feet, often takeoff with one foot leading  Limited extension of the hips, knees and ankles for propulsion Landing phase  Arms may move forward for balance  Slight forward lean of the trunk, < 30°  Difficulty in landing on both feet simultaneously  Poor flexion of the leg for absorption during landing With changes in strength and co-ordination, the child would improve on the quality of the jump, resulting in increased distance achieved in standing broad jump performance. The following describes the elementary stage of horizontal jumping: Preparatory phase  Arms remain in front of body in preparatory crouch  Trunk leans forward at about 30° or more  Deeper preparatory crouch with flexion at the hip, knee and ankle flexion Takeoff phase  Arms initiate jumping action, by swinging forward  Arms held out to the sides to assist with balance  Trunk maintains forward leanBSE201 STUDY UNIT 4 SU4-12  Takeoff consistently on both feet  Increased extension of the hips, knees and ankles for propulsion  Hips and knees maintain a flexed position during flight Landing phase  Arms may move forward for balance  Slight forward lean of the trunk, < 30°  Centre of gravity is positioned above the base of support  Consistently land with feet together  Increased flexion of the knees for absorption during landing On average at about 6 years of age, the child would achieve a mature jumping pattern, with performance improving with greater strength gains. The following describes the mature stage of horizontal jumping: Preparatory phase  Arms move high and to the rear  Trunk leans forward at about 45°  Deep and consistent preparatory crouch with flexion at the hip, knee and ankle flexion Takeoff phase  Arms swing forward with force to assist with forward propulsion  Arms maintained in a high position during flight  Trunk maintains forward lean angle  Complete extension of the hips, knees and ankles for propulsion  Hips and knees maintain a flexed position, with the thigh parallel to the ground Landing phase  Arms reach forward  Trunk leans forward for landing  Body weight shifts forward at landing  Flexion of the knees for absorption during landingBSE201 STUDY UNIT 4 SU4-13 1. Design a qualitative checklist to assess children's jumping performance and running gait. 2. Discuss the types of training that can be conducted to improve running and jumping proficiency. You should now read Haywood, Kathleen & Getchell, Nancy. (2009). Life Span Motor Development (5th ed.). Human Kinetics. pp118-130. 8.2 Fundamental Object Control Skills With the ability to move around freely, children begin to explore their environment more effectively. Children begin to use their hand to manipulate objects, and would often exhibit a category of skills referred to as fundamental object control skills. Object control skills often involve two aspects of movement, i.e. ballistic and receptive movements. Ballistic skills involve movements in which the individual applies force to an object, moving the object away from the body. Examples of ballistic skills are throwing, kicking and striking. Receptive skills involve movements in which an individual gains possession or control of an object by positioning himself/herself in the path of the moving object. Examples of receptive skills are catching and trapping. With time, experience and practice of object control skills, children learn to make more accurate estimates of the moving object in space. 8.2.1 Overarm Throwing There are a few different forms of throwing patterns, such as the overarm throw, two-handed throw and side throw. The most common of these is the overarm throw, as it is most widely used in sport. The moment a child learns to perform a voluntary release of an object, he/she would soon be observed to perform the skill of throwing, at about 1 year of age. The overarm throw can be broken down to the following phases: the preparatory phase, execution phase and follow-through phase.BSE201 STUDY UNIT 4 SU4-14 Developmental sequence for overarm throwing The first study to observe the developmental sequence of overarm throwing was conducted by Monica Wild (1938). She observed that movement patterns for overarm throwing developed from a distal to proximal direction, whereby the throwing action of young children was restricted to only arm action, with elbow extension alone. The initial stage of throwing is described as follows: Preparatory phase  Elbow positioned in front of the body  Trunk is positioned frontward to the direction of throw  Small movements in feet position Execution phase  Extension of the elbow  Fingers spread at ball release  No trunk movement  Both feet remain stationary  Limited extension of the hips, knees and ankles for propulsion Follow-through phase  Follow-through is forward and downward As the child continues to practise the skill of overarm throwing, he/she would begin to free up the degrees of freedom, which can be observed by including the shoulders, hips and legs in the throwing action, with increased weight transference. The elementary stage of throwing is described as follows: Preparatory phase  Upward backswing can be seen with the arm swung upward, sideward and backward, with elbow flexion  Ball is positioned behind the head  Trunk is slightly rotated to the throwing side  The foot on the same side of the throwing arm is positioned slightly forwardBSE201 STUDY UNIT 4 SU4-15 Execution phase  The upper arm and forearm swing forward, aligned with the shoulder  Trunk flexes forward  Transference of weight forward  Steps forward with the foot on the same side as the throwing arm Follow-through phase  Follow-through is forward and downward with some flexion and rotation of the trunk towards the opposite side of the throwing arm Finally, with continued practice and improved co-ordination, the child achieves proficient movement of the overarm throw at about 8 years of age. The mature stage of throwing is described as follows: Preparatory phase  Circular backswing  Opposite arm is raised for balance  Trunk is rotated to the throwing side  The foot on the opposite side of the throwing arm is positioned slightly forward Execution phase  The upper arm moves forward horizontally  Smooth sequencing of upper limb movement, with extension of the elbows occurring immediately after the elbow is forward facing  Differentiated trunk rotation, starting from the hips, spine and shoulders  Transference of weight forward  A long step forward with the foot on the same side as the throwing arm Follow-through phase  Follow-through is forward and downward with some flexion and rotation of the trunk towards the opposite side of the throwing armBSE201 STUDY UNIT 4 SU4-16 8.2.2 Catching The skill of catching involves a high degree of hand-eye co-ordination in order to position oneself in the path of the object to stop and acquire possession of it. Handeye co-ordination involves vision and perception of the moving object, and the positioning of the body according to the visual information, also known as perception-action coupling. Visual sensation develops throughout childhood, with perfect vision only developing at around the age of 10. Perception of movement is the ability to perceive the direction, location, and speed of the object. Perception of movement becomes more accurate with increased visual sensation together with trial and error through experience during childhood. The skill of catching can therefore be divided into two components, (1) the preparation phase, whereby the individual perceives the direction and speed of the ball, and positions himself in the path of the object; and (2) the reception phase, in which the individual adjusts the body to absorb the impact of the object. Developmental sequence for two-handed catching The initial stage of catching is described as follows: Preparatory phase  Arms held in front of the body, with elbows extended  Palms are held facing upwards  Limited body movement Reception phase  Traps the ball against the body and arms  Hands are often not used to trap the ball  Fingers are stiff and extended With practice and improved visual perception, the hands become more involved in trapping the ball. Hence, the elementary stage of catching is described as follows: Preparatory phase  Elbows are positioned near the body, with elbows flexed  Palms are held facing each other with the thumbs facing up  Arms and trunk begin to move toward the path of the ballBSE201 STUDY UNIT 4 SU4-17 Reception phase  Initial contact with hands  Occasionally still traps the ball against the body with the arms  Poor timing and uneven hand closure on the ball By about 8 years of age, most children achieve the proficiency of the elementary stage, with some adjustment in body position to flight path of the ball. However, it is not till about 11 years of age where children are able to successfully adjust their body position majority of the time, and display proficient two-handed catching. The mature stage of catching is described as follows: Preparatory phase  Slight flexion of the elbows, in a relaxed position  Arms extend to meet the ball  Hand and fingers adjusted to the size of the ball  Feet, trunk and arms move to adjust to flight path of the ball Reception phase  Arms flex slightly upon contact with the ball to absorb the force of the ball  Both hands grasp the ball simultaneously  Timely closure of the hand and fingers around the ball Explain how environmental and task constraints may influence the development of fundamental object control skills. You should now read Haywood, Kathleen & Getchell, Nancy. (2009). Life Span Motor Development (5th ed.). Human Kinetics. pp.143-155; 177-185.BSE201 STUDY UNIT 4 SU4-18 8.3 Factors Affecting the Development of Fundamental Movement Skills 8.3.1 Experience Since the early 1900's there has been an ongoing debate on the importance of maturation and experience in the development of fundamental movement abilities. Since then, a number of twin studies have been conducted to examine the impact of training on the development of specific movement skills. Initial twin studies by Gesell (1929) and McGraw (1935, 1939) found no effects of training on the development of stair climbing and a number of other more advanced movement skills. As mentioned earlier on in Unit 1, McGraw's classic study of Johnny and Jimmy (McGraw 1935) examined the influence of enhanced experience on the development of a number of advanced movement skills, where Johnny was provided with earlier training and Jimmy with minimal motor stimulation. In her findings, McGraw suggested that there were critical periods dependent on the maturational status of the nervous system where improvement through practice becomes feasible. However, when the twins were retested four years later, performances by Johnny and Jimmy on most of the tasks were similar. However, it was noted that Johnny seemed to display a superiority of general muscular co-ordinations, which was attributed to the longer exposure to motor activities. One very interesting finding was the effect of roller skating training on skating performance. Johnny having received earlier training was able to skate at about 1 year of age, however Jimmy never caught up with Johnny in skating during his catch-up training period. However, with discontinued training in both twins, the performance of skating declined rapidly, with both Johnny and Jimmy having difficulty in performing the skill at the age of 4. This led McGraw to believe that the ability to retain a skill depends on how well established it was before it was discontinued. Furthermore, in the development of many of the fundamental movement skills, practice with the assistance of an instructor is considered to play an important role in the rate of development of the movement pattern. Although practice has minimal impact on the developmental sequence of movement patterns, it does affect the onset and rate of development of certain movement skills. 8.3.2 Body Composition Over the past 30 years, increasing rates of childhood obesity have been reported in many countries, with prevalence rates being equally high in developed andBSE201 STUDY UNIT 4 SU4-19 developing countries. Similarly, the rate of obesity in Singapore had been increasing over the past few years, and is now at 11%. With the prevalence of overweight children on the rise, numerous studies have investigated the impact of high body mass index (BMI) on fundamental movement skill performance. Several studies have reported a negative relationship between body composition and locomotor skill proficiency, such as running and jumping (Okely, Booth, & Chey, 2004; Southall, Okely, & Steele, 2004). As locomotor skills require the transportation of the entire body mass, children who have a larger body mass would experience greater biomechanical movement inefficiency while moving their body against gravity (Okely et al., 2004). In addition, overweight children are more likely to have musculoskeletal complications, such as slipped capital femoral epiphyses (Loder, 1996) and flat feet (Riddiford-Harland, Steele, & Storlien, 2000), which may lead to greater inefficiency and pain while participating in physical activity. 8.3.3 Social and Cultural Constraints Social and cultural constraints are social and cultural factors that influence the type of physical activity that an individual participates in. The introduction of female competitions in the Olympics suggests a change in social norms in which it is acceptable for women to participate in sport. This change in socio-cultural view has seen a dramatic increase in females participating in sport. Despite the increasing acceptance of females participating in sport, society often associate males with masculinity and females with femininity. This differentiation between genders is also known as gender typing. As such, parents often encourage boys to participate in rough-and-tumble play, which include running, jumping and climbing. Females on the other hand are discouraged and often punished for participation in such activities (Campbell & Eaton, 2000). As children grow older, the effects of gender typing become more pronounced, with males being more proficient in movement skills and participating more in physical activity as compared to their female counterparts (Barnett et al., 2010; Hume et al., 2008). Similarly, family members, peers and teachers also play a role in determining the development of fundamental movement skills from a social context. In a child's early years, parents play an important role in exposing or encouraging their child to move and explore new things. If parents encourage their children from a young age to participate in sport, it is very likely that the child would lead a lifetime of participation in physical activity (Weiss & Barber, 1996). In addition, mothers who are active in sport tend to set an example for their daughters to also engage actively in physical activity (DiLorenzo et al., 1998; McPherson, 1978). In the same way, peersBSE201 STUDY UNIT 4 SU4-20 also influence physical activity participation if most of the individuals are involved in a specific sport in school. Lastly, teachers play an important role in making sport interesting by introducing new games and skills thus constantly engaging the children to enjoy sport. In addition, they are also able to influence a child's participation by encouraging them and recognising their potential in sport. You should now read Haywood, Kathleen & Getchell, Nancy. (2009). Life Span Motor Development (5th ed.). Human Kinetics. Chapter 12.BSE201 STUDY UNIT 4 SU4-21 Quiz 1. Which of the following 2 periods do we see the greatest rate of physical growth? a) Early childhood and adolescence b) Infancy and childhood c) Infancy and adolescence d) Childhood and adulthood 2. At what age is the cerebral cortex considered to be structurally developed? a) 4 b) 6 c) 8 d) 10 3. Which characteristic of cognitive development during childhood is false? a) They are eager to learn new things b) They are capable of abstract thinking c) Their working memory improves rapidly d) They are able to understand concrete examples 4. Which of the following statements is true about the development of throwing? a) Throwing develops in a proximal-distal direction b) Throwing develops in a distal-proximal direction c) Throwing develops in a cephalocaudal direction d) Throwing develops in a cephalocaudal direction and proximal-distal direction 5. Which of the following fundamental skills is a child likely to exhibit first? a) Throwing b) Running c) Jumping d) CatchingBSE201 STUDY UNIT 4 SU4-22 6. In the development of running, which of the following is considered to be a major rate controller? a) Flexibility b) Co-ordination c) Strength d) Practice 7. Which of the following fundamental movement skills takes the longest to develop? a) Throwing b) Running c) Jumping d) CatchingBSE201 STUDY UNIT 4 SU4-23 Summary Childhood is an important period of physical and cognitive development. Physical growth develops in a predictable manner although this may vary from individual to individual. In addition, this period is also a very sensitive period, whereby factors such as nutrition, physical activity and illnesses can lead to lifelong stunted growth or retardation during this period of development. Despite the poor understanding of the direct relationship between neural and cognitive development, developmental psychologists have observed that children tend to be more curious about their environment, and are able to understand concrete information. Attention and working memory improve rapidly during this period, although they still struggle with abstract reasoning and decision making. The development of proficient fundamental movement skills during childhood is crucial for the further participation in sport and games. Although the development of fundamental movement skills progresses in an orderly sequence, individual constraints (such as strength, balance and co-ordination), environmental constraints (such as practice and parental encouragement), and tasks constraints (such as ball size and weight) play an important role in influencing the timing and rate of acquisition of the skill.BSE201 STUDY UNIT 4 SU4-24 References Barnett, L.M., van Beurden, E., Morgan, P.J., Brooks, L.O., & Beard, J.R. (2010). Gender differences in motor skill proficiency from childhood to adolescence: A longitudinal study. Research Quarterly for Exercise and Sport, 81(2), 162-170. Campbell, D., & Eaton, W. (2000). Sex differences in the activity level of infants. Infant and Child Development, 8, 1-7. Casey, B.J., Galvan, A., & Hare, T.A. (2005). Changes in cerebral functional organization during cognitive development. Current Opinion in Neurobiology, 15, 239- 244. Claessens, A.L., Malina, R.M., Lefevre, J., et al. (1992). Growth and menarcheal status of elite female gymnasts. Medicine and Science in Sports and Exercise, 24, 755-763. Daniels, S.R., Jacobson, M.S., McCrindle, B.W., Eckel, R.H., & Sanner, B.M. (2009). American Heart Association childhood obesity research summit report. Circulation, 119, e489-517. Dicharry, J. (2010). Kinematics and kinetics of gait: From lab to clinic. Clinics in Sports Medicine, 29, 347-364. DiLorenzo, T., Stucky-Ropp, R., Vander Wal, J., & Gotham, H. (1998). Determinants of exercise among children: II. A longitudinal analysis. Preventive Medicine, 27, 470- 477. Dugan, S.A., & Bhat, K.P. (2005). Biomechanics and analysis of running gait. Physical Medicine and Rehabilitation Clinics of North America, 16, 603-621. Erladson, M.C., Sherar, L.B., Milwald, R.L., et al. (2008). Growth and maturation of adolescent female gymnasts, swimmers, and tennis players. Medicine and Science in Sports and Exercise, 40, 34-42. Gallahue, D., Ozmun, J., & Goodway, J. (2011). Understanding motor development: Infants, children, adolescents, adults (7th ed.). New York: McGraw-Hill. Georgopoulos, N.A., Roupas, N.D., Theodoropoulou, A., et al., (2010). The influence of intensive physical training on growth and pubertal development in athletes. Annals of the New York Academy of Sciences, 1205, 39-44.BSE201 STUDY UNIT 4 SU4-25 Gesell, A. (1929). Infancy and human growth. New York: Macmillan. Gogtay, N., Giedd, J.N., Lusk, L., et al. (2004). Dynamic mapping of human cortical development during childhood through early adulthood. Proceedings of the National Academy of Sciences of the United States of America, 101, 8174-8179. Han, J.C., Lawlor, D.A., & Kimm, S.Y.S. (2010). Childhood obesity. Lancet, 375, 1737- 1748. Hume, C., Okely, A.D., Bagley, S., Telford, A., Booth, M., et al. (2008). Does weight status influence associations between children’s fundamental movement skills and physical activity? Research Quarterly for Exercise and Sport, 79, 158-165. Loder, R.T. (1996). The demographics of slipped capital femoral epiphysis: An international multicenter study. Clinical Orthopaedics and Related Research, 322, 8-27. Luciana, M., & Nelson, C.A. (1998). The functional emergence of prefrontallyguided working memory systems in four- to eight-year-old children. Neuropsychologia, 36, 273-293. Mann, R.A., & Hagy, J. (1980). Biomechanics of walking, running and sprinting. The American Journal of Sports Medicine, 8(5), 345-350. McGraw, M.B. (1935). Growth: A study of Johnny and Jimmy. New York: AppletonCentury. McGraw, M.B. (1939). Later development of children specially trained during infancy. Child Development, 10, 1. McPherson, B.D. (1978). The child in competitive sport: Influence of the social milieu. In R.A. Magill, M.J. Ash, & F.L. Smoll (Eds.), Children in sport: A contemporary anthology (pp.219-249). Champaign, IL: Human Kinetics. Novacheck, T.F. (1998). The biomechanics of running. Gait and Posture, 7, 77-95. Oakley, L. (2004). Cognitive development. East Sussex: Routledge. Okely, A.D., Booth, M., & Chey, T. (2004). Relationship between body composition and fundamental movement skills among children and adolescents. Research Quarterly for Exercise and Sport, 75, 238-247.BSE201 STUDY UNIT 4 SU4-26 Ounpuu, S. (1994). The biomechanics of walking and running. Clinics in Sports Medicine, 13(4), 843-863. Reilly, J.J. (2005). Descriptive epidemiology and health consequences of childhood obesity. Best Practice and Research Clinical Endocrinology, 19, 327-341. Riddiford-Harland, D.L., Steele, J.R., & Storlien, L.H. (2000). Does obesity influence foot structure in prepubescent children? International Journal of Obesity, 24, 1-4. Southall, J.E., Okely, A.D., & Steele, J.R. (2004). Actual and perceived competence in overweight and non-overweight children. Pediatric Exercise Science, 16, 15-24. Sowell, E.R., Thompson, P.M., Leonard, C.M., Welcome, S.E., Kan, E., & Toga, A.W. (2004). Longitudinal mapping of cortical thickness and brain growth in normal children. The Journal of Neuroscience, 24, 8223-8231. Victora C.G., Adair L., Fall C., et al. (2008). Maternal and child under-nutrition: Consequences for adult health and human capital. Lancet, 371, 340-357. Weiss, M.R., & Barber, H. (1996). Socialization influences of collegiate male athletes: A tale of two decades. Sex Role, 33, 129-140. Whitall, J., & Caldwell, G.E. (1992). Coordination of symmetrical and asymmetrical human gait. Journal of Motor Behaviour, 24(4), 339-353. Wild, M. (1938). The behavior pattern of throwing and some observations concerning its course of development in children. Research Quarterly, 9, 20-24. Whittle, M.W. (2007). Gait analysis: An introduction. Edinburgh: Butterworth Heinemann/Elsevier.BSE201 STUDY UNIT 4 SU4-27 Solutions or Suggested Answers 1. c) Infancy and adolescence 2. a) 4 3. b) They are capable of abstract thinking 4. b) Throwing develops in a distal-proximal direction 5. a) Throwing 6. c) Strength 7. d) CatchingSTUDY UNIT 5 ADOLESCENCEBSE201 STUDY UNIT 5 SU5-1 Chapter 9 Adolescent Growth Learning Outcomes By the end of this chapter, you should be able to: 1. describe hormonal factors associated with the onset of puberty 2. describe the changes in height and weight that occur during the adolescent growth spurt 3. discuss possible factors that influence the onset of puberty 4. discuss the relationship between major changes in body composition and physiological functioning in adolescent males and females 5. describe gender differences and similarities in health-related fitness Overview Adolescence is described as the transition period between childhood and adulthood (Santrock, 2005). The beginning adolescence is marked by the onset of puberty, which drives many of the biological changes observed during this period. The period of adolescence is characterised by substantial physical growth, as well as dramatic changes in emotion, cognition and behaviour. Therefore, the first half of this chapter would review the mechanisms controlling and influencing adolescent growth, and the resultant changes observed. In addition, as puberty influences growth differentially between genders, this also marks the beginning of differences in fitness outcomes between male and female, which lasts throughout adulthood.BSE201 STUDY UNIT 5 SU5-2 9.1 Physical Growth 9.1.1 Onset of Puberty The beginning of the adolescent growth spurt is marked by the onset of puberty, which leads to the changes observed in height, weight and body composition. Puberty is the start of sexual maturation characterised by the development of genital organs, secondary sexual characteristics, mood and behaviour. The determinants of the timing of puberty have been established to be of a genetic origin, although the rate at which puberty occurs can be influenced by the interaction between genetics and environmental circumstances (Parent et al., 2003). More recently, there is increasing evidence to recognise the impact that the imbalance of energy reserves stored in the body has on modifying the onset of puberty. Leptin, an adipose hormone has been identified as a crucial signal permitting for the onset of puberty, while ghrelin (a hormone signalling energy insufficiency) has been suggested to work as a inhibitory signal for gonadotropin secretion (Casanueva & Dieguez, 1999; Tena-Sempere, 2007, 2008a,b). Both leptin and ghrelin have been suggested to act indirectly in the control of the gonadotropinreleasing hormone (GnRH) neuronal system at the hypothalamus, with the permissive and inhibitory effects transmitted through the kisspeptin neurons (Castellano et al., 2009; Forbes, Li, Kinsey-Jones, & O'Byrne, 2009). In situations when there is an excess of fat mass, early onset of puberty may be facilitated (Roa et al., 2010, Figure 5.1). In this instance, excess levels of leptin act as a permissive signal on kisspeptin neurons for the secretion of gonadotropin-releasing hormones at the hypothalamus, thereby resulting in the synthesis and secretion of growth hormones, luteinising hormone and follicle stimulating hormone by the anterior pituitary gland. The secretion of the luteinising hormone and follicle stimulating hormone stimulates the growth of the gonads, ovaries in females, and testes in males. Although leptin may not necessarily act as a trigger for the onset of puberty, it has been suggested that threshold levels of leptin are mandatory for puberty to ensue. This may be a possible explanation for the increasing trend for lowering of the average age of puberty to as early as 8 years of age.BSE201 STUDY UNIT 5 SU5-3 Figure 5.1 Metabolic control in modifying puberty onset (Source: Adapted from Roa et al., 2010) Similarly, in situations whereby an individual who is undernourished and leaner, the high levels of ghrelin inhibit the secretion of gonadotropin-releasing hormones at the hypothalamus through the kisspeptin neuron, thereby preventing the secretion of growth hormones, luteinising hormone and follicle stimulating hormone by the anterior pituitary gland (Figure 5.1). Although increased levels of ghrelin have been suggested to be associated with the delayed onset of puberty through the above mentioned mechanism, the direct mechanisms remain elusive (Roa et al., 2010). At the onset of puberty, the release of luteinising hormone and follicle stimulating hormone by the anterior pituitary gland results in the growth and development of the ovaries and testes, which produces oestrogen and testosterone respectively. These hormones, together with growth hormone produced by the anterior pituitary gland are responsible for the major structural changes that occur during the adolescent growth spurt (Figure 5.2). GnRH Kisspeptin Neuron Leptin Abundance of energy Ghrelin Insufficient energy LH FSH Anterior pituitary gland HypothalamusBSE201 STUDY UNIT 5 SU5-4 Figure 5.2 Hormonal influence of the hypothalamo-pituitary axis on the growth plate (Source: Adapted from Wei & Gregory, 2009) 9.1.2 Changes in Height The adolescent growth spurt is the second period of rapid growth experienced by an individual. The adolescent growth spurt on average lasts for about seven years, with the female growth spurt beginning at age 9 and ending at about 16 years of age, and males starting their growth spurt two years later, beginning at age 11, and ending at about 18 years of age (Haywood & Getchell, 2009). Although the final height that is achieved in an individual is genetically determined, similar to the onset of puberty, an individual's phenotype (how one's genotype is expressed) can be influenced by the environment. Skeletal maturation is largely facilitated by the growth hormone and insulin-like growth factors (IGF-1). The growth hormone as mentioned in the previous section is produced by the anterior pituitary gland and is regulated by the growth releasing hormone within the hypothalamus. Accordingly, the increase in growth hormones stimulates the liver to produce insulin-like growth factors. Both the growth hormone and insulin-like growth factors lead to bone formation through proliferation of the cartilage cells at the growth plates of long bones, resulting in growth in length of individual bones (Saggese, Baroncelli, & Bertelloni, 2002). In addition, it has also been established that oestrogen plays an important role in the bone growth during puberty, with low doses of oestrogen stimulating bone growth and high levels of oestrogen inhibiting bone growth through the fusion of the epiphyseal plates (Cutler Jr, 1997; Nilsson, Marino, De Luca, Phillip, & Baron, 2005). With the onset of puberty in females, the initial low levels of oestrogen together with Anterior pituitary gland Hypothalamus Liver Bone structure Growth Hormone LH FSH IGF-1 Ovaries TestesBSE201 STUDY UNIT 5 SU5-5 the growth hormones and insulin-like growth factors result in peak growth spurt at about 11 years of age. Males on the other hand undergo puberty at a later age (~2 years later than girls), giving more time for continual growth in height. Furthermore, the release of testosterone also stimulates longitudinal bone growth in males with the peak growth spurt occurring at about 13 years of age. The testosterone produced in males also aromatises to produce estradiol which is similar to that of oestrogen, thereby stimulating the fusion of the epiphyseal plates. The later occurrence of the growth spurt in males also explains the higher stature achieved in males as compared with females (Mauras, Bishop, & Welch, 2007). 9.1.3 Changes in Body Composition During childhood, physical growth and body composition remain largely similar between males and females. However, during the adolescent growth spurt, the differences in body composition between male and female become more significant. Males develop greater muscle mass, which accounts for 54% of men's body weight whereas for women’s muscle mass, it accounts for 45% of women's body weight (Haywood & Getchell, 2009). Females begin to develop greater amounts of adipose tissue, accounting for ~35%, whereas for males, it is ~15% (Horlick et al., 2000). These differences in body composition between male and female are attributed in part by the sex hormones produced by the gonads. The increase in oestrogen production and circulation during puberty in females, is thought to favour fat storage, particularly in peripheral adipose tissue (Garnett et al., 2004; Rosenbaum & Leibel, 1999). However, during puberty in males, the increased production and circulation of testosterone favours the increase in lean tissue mass and storage of abdominal fat (Garnett et al., 2004; Rosenbaum & Leibel, 1999). Lastly, at the end of the growth spurt during the adolescent period, the greater muscle mass and higher stature contribute to the greater body weight in males as compared to females. You should now read Gallahue, David, Ozman, John, & Goodway, Jacqueline. (2011). Understanding Motor Development: Infants, Children, Adolescents, Adults (7th ed.). McGraw-Hill. Chapter 15.BSE201 STUDY UNIT 5 SU5-6 9.2 Fitness Changes 9.2.1 Aerobic Fitness Aerobic fitness is dependent on the ability of the heart and lungs to transport oxygen to the working muscles in order to engage in prolonged physical activity. During childhood, although stroke volume and haemoglobin levels are smaller than that of adults, this is compensated with the higher heart rates and increased ability to extract oxygen to the active muscles. However, this changes during puberty, with increases in heart size, increases in haemoglobin concentration and lung capacity. With changes in musculature, heart and stroke volume, total haemoglobin and lung volume, aerobic capacity increases throughout adolescence, with a greater increase in males as compared to females. As there exists a strong relationship between aerobic fitness (maximal aerobic capacity) and muscle mass, the greater increase in muscle mass observed in males is likely to attribute to the increased aerobic fitness measured in males (Haywood & Getchell, 2009). In contrast, females experience greater increase in adipose tissue as opposed to muscle mass, as well as lower haemoglobin concentrations which explains the lower aerobic fitness in females. However, important to note, environmental factors also influence aerobic fitness, especially aerobic training which may improve aerobic fitness at any point throughout the lifespan. 9.2.2 Anaerobic Fitness Anaerobic fitness comprises performances that activate the short-term energy system for a maximum exercise of up to 3 minutes (Bar-Or, 1987). Before the onset of puberty, children tend to have lower anaerobic fitness due to the relatively lower glycogen concentrations in the muscle tissue as compared to adults. With the adolescent growth spurt, particularly the increases in muscle mass partly account for the differences observed between genders, with males attaining higher anaerobic fitness scores (Perez-Gomez et al., 2008). As evidenced from cross-sectional studies, total work output scores improve throughout the adolescent period for males, whereas it tapers off at about 14 years of age in females (Haywood & Getchell, 2009). Similarly as with aerobic fitness, anaerobic training has been demonstrated to improve anaerobic performance in both males and females (Sitkowski & Grucza, 2009). 9.2.3 Strength Muscular strength is the ability to apply force against an object. As the development of muscular strength is largely dependent on muscle mass, the greater the cross-BSE201 STUDY UNIT 5 SU5-7 sectional area of the muscle, the greater the ability of that muscle to produce and exert force. Muscular strength of both the quadriceps and elbow flexors has been reported to increase steadily from 8 to 12 years in both males and females. However, like anaerobic fitness, the muscle groups in males continued to increase in strength even after the end of the growth spurt during adolescence (Parker, Round, Sacco, & Jones, 1990). This continued increase in strength gains in males has been directly attributed to the increasing levels of testosterone in males, resulting in greater muscle growth, as well as the growth in length of the humerus leading to greater upper limb strength (Round, Jones, Honour, & Nevill, 1999). As the amount of force that a muscle group can exert is dependent on muscle mass and the ability to activate the muscle fibres of the relevant muscles, strength training is a key environmental factor that influences changes in strength. Previous studies examining the differences in strength have often involved either prepubescent children or adults, and observed the differences between genders. In a recent study investigating the effect of strength training in adolescent males and females, Muehlbauer and colleagues (2012) found that high velocity strength training improved relative and absolute jump height significantly in both male and female adolescents, which were attributed to increase in motor neuron firing frequency, motor unit activation and inter-muscular co-ordination. In addition, it was interesting to note that the female adolescents were found to have greater gains in maximal isometric force and rate of force development as compared to the male adolescents. However, it was suggested that the strength training protocol used for this study could have favoured the female adolescents given that the exercise intensities were not high enough to induce muscle hypertrophy in male adolescents. As such, it is suggested that both males and females adapt differently to the type and intensity of training in order to gain strength benefits. 9.2.4 Flexibility Flexibility is the ability of an individual to move the limbs through a full range of motion around the joint. Flexibility is often important as it enables one to develop power by moving the limb through a greater range of motion, in addition, flexibility also reduces the risk of musculoskeletal injury. Flexibility like the other aspects of fitness can be trained and reversed. An individual is able to improve the range of motion in a joint by regularly moving through the full range of motion and slowly increasing the range to increase the elasticity of the soft tissue around the joint. The reverse is the same when an individual rarely moves the joint through its full range of motion, thereby causing the soft tissue around the particular joint to lose its elasticity.BSE201 STUDY UNIT 5 SU5-8 Most longitudinal and cross-sectional studies have reported the decreasing trend in flexibility with age (Clarke, 1975; Krahenbuhl & Martin, 1977). At about the age of 6, flexibility scores tend to decline when performing the sit-and-reach test (Ross, Pate, Delpy, Gold, & Svilar, 1987). This decrease in flexibility during the adolescent growth spurt has been suggested to be a result of the long bones growing at a faster rate than the muscles and tendons. However, flexibility has been noted to improve once the muscles and tendons catch up with the growth of the long bones (Gallahue, Ozman, & Goodway, 2011). It has also been found that females in general have better flexibility scores as compared to males. It has been suggested that stretching exercises, such as gymnastics, dance and ballet may be more acceptable in females in the socio-cultural context than vigorous physical activity (Malina, Bouchard, & BarOr, 2004). The decline of flexibility with age has been mainly associated to the level of activity participation, whereby high levels of joint flexibility can be maintained with the appropriate and adequate activities. You should now read Haywood, Kathleen & Getchell, Nancy. (2009). Life Span Motor Development (5th ed.). Human Kinetics. Chapter 15 & 16. Understanding the development of fundamental movement skills (Unit 4) as well as the development aerobic and anaerobic fitness, strength and flexibility in childhood through to adolescence, how would you as physical educators plan the PE curriculum to achieve the best fitness/movement performance for your students?BSE201 STUDY UNIT 5 SU5-9 Quiz 1. Which hormone plays a role in influencing an earlier onset of puberty? a) Ghrelin b) Insulin c) Growth hormone d) Leptin 2. Which hormone is responsible for the fusion of the epiphyseal plate in skeletal maturation? a) Oestrogen b) Growth hormone c) Insulin-like growth factor d) Testosterone 3. Why are males taller and heavier than females? 4. Why are males more aerobically fit? a) Greater muscle mass b) Higher heart rate c) Greater stroke volume d) All the above 5. Strength and resistance training improves vertical jump performance as a result of _________? a) Muscle hypertrophy b) Increased muscle-unit activation c) Inter-muscular co-ordination d) All the aboveBSE201 STUDY UNIT 5 SU5-10 Summary The adolescent period is a time of great change with regards to physical appearances and functional capabilities. The onset of puberty is the reason for which many of these changes take place. The release of hormones by the anterior pituitary gland, causes the growth of the gonads which in return release the sex specific hormones, resulting in the differences in height and body composition, as well as the gender differences observed in fitness outcomes. Although there is a great individual constraint in the development of these differences between genders, environmental constraints such as training and nutrition would also play a role in influencing the onset of puberty, height, body composition, and fitness outcomes.BSE201 STUDY UNIT 5 SU5-11 References Bar-Or, O. (1987). The Wingate anaerobic test: An updates on methodology, reliability, and validity. Sports Medicine, 4, 381-394. Casanueva, F.F., & Dieguez, C. (1999). Neuroendocrine regulation and actions of leptin. Frontiers in Neuroendocrinology, 20(4), 317-363. Castellano, J.M., Roa, J., Luque, R.M., Dieguez, C., Aguilar, E., Pinilla, L., & TenaSempere, M. (2009). Kiss-1/kisspeptins and the metabolic control of reproduction: Physiological roles and putative physiopathological implications. Peptides, 30, 139- 145. Clarke, H.H. (Ed.). (1975). Joint and body range of movement. Physical Fitness Research Digest, 5, 16-18. Cutler Jr, G.B. (1997). The role of oestrogen in bone growth and maturation during childhood and adolescence. The Journal of Steroid Biochemistry and Molecular Biology, 61, 141-144. Forbes, S., Li, X.F., Kinsey-Jones, J., & O'Byrne, K. (2009). Effects of ghrelin on Kisspeptin mRNA expression in the hypothalamic medial preoptic area and pulsatile luteinising hormone secretion in the female rat. Neuroscience Letters, 460, 143-147. Gallahue, D., Ozman, J., & Goodway, J. (2011). Understanding motor development: Infants, children, adolescents, adults (7th ed.). McGraw-Hill. Garnett, S.P., Högler, W., Blades, B., Baur, L.A., Peat, J., Lee, J., & Cowell, C.T. (2004). Relation between hormones and body composition, including bone, in prepubertal children. The American Journal of Clinical Nutrition, 80, 966-972. Haywood, K., & Getchell, N. (2009). Life Span Motor Development (5th ed.). Champaign, IL: Human Kinetics. Horlick, M.B., Rosenbaum, M., Nicolson, M., Levine, L.S., Fedun, B., Wang, J., Pierson Jr, R.N., & Leibel, R.L. (2000). Effect of puberty on the relationship between circulating leptin and body composition. The Journal of Clinical Endocrinology and Metabolism, 85, 2509-2518.BSE201 STUDY UNIT 5 SU5-12 Krahenbuhl, G.S., & Martin, S.L. (1977). Adolescent body size and flexibility. Research Quarterly, 48, 797-799. Malina, R.M., Bouchard, C., & Bar-Or, O. (2004). Growth, maturation and physical activity (Chapter 11). Champaign, IL: Human Kinetics. Mauras, N., Bishop, K., & Welch, S. (2007). Growth hormone action in puberty: Effects by gender. Growth Hormone and IGF Research, 17, 463-471. Muehlbauer, T., Gollhofer, A., & Granacher, U. (2012). Sex-related effects in strength training during adolescence: A pilot study. Perceptual and Motor Skills, 115, 953-968. Nilsson, O., Marino, R., De Luca, F., Phillip, M., & Baron, J. (2005). Endocrine regulation of the growth plate. Hormone Research in Paediatrics, 64, 157-165. Parent, A.S., Teilmann, G., Juul, A., Skakkebaek, N.E., Toppari, J., & Bourguignon, J.P. (2003). The timing of normal puberty and the age limits of sexual precocity: Variations around the world, secular trends, and changes after migration. Endocrine Reviews, 24, 668-693. Parker, D.F., Round, J.M., Sacco, P., & Jones, D.A. (1990). A cross-sectional survey of upper and lower limb strength in boys and girls during childhood and adolescence. Annals of Human Biology, 17, 199-211. Perez-Gomez, J., Rodriguez, G.V., Ara, I., Olmedillas, H., Chavarren, J., GonzalezHenriquez, J.J., Dorado, C., & Calbet, J.A.L. (2008). Role of muscle mass on sprint performance: Gender differences? European Journal of Applied Physiology, 102, 685-694. Roa, J., Garcia-Galiano, D., Castellano, J.M., Gaytan, F., Pinilla, L., & Tena-Sempere, M. (2010). Metabolic control of puberty onset: New players, new mechanisms. Molecular and Cellular Endocrinology, 324, 87-94. Rosenbaum, M., & Leibel, R.L. (1999). Clinical review 107: Role of gonadal steroids in the sexual dimorphisms in body composition and circulating concentrations of leptin. The Journal of Clinical Endocrinology and Metabolism, 84, 1784-1789. Ross, J.G., Pate, R.R., Delpy, L.A., Gold, R.S., & Svilar, M. (1987). New health-related fitness norms. Journal of Physical Education, Recreation and Dance, 58, 66-70.BSE201 STUDY UNIT 5 SU5-13 Round, J.M., Jones, D.A., Honour, J.W., & Nevill, A.M. (1999). Hormonal factors in the development of differences in strength between boys and girls during adolescence: A longitudinal study. Annals of Human Biology, 26, 49-62. Saggese, G., Baroncelli, G.I., & Bertelloni, S. (2002). Puberty and bone development. Best Practice and Research Clinical Endocrinology and Metabolism, 16, 53-64. Santrock, J.W. (2005). Adolescence. New York: McGraw-Hill. Sitkowski, D., & Grucza, R. (2009). Age-related changes and gender differences of upper body anaerobic performance in male and female sprint kayakers. Biology of Sport, 26, 325-338. Tena-Sempere, M. (2007). Roles of ghrelin and leptin in the control of reproductive function. Neuroendocrinology, 86, 229-241. Tena-Sempere, M. (2008a). Ghrelin and reproduction: Ghrelin as novel regulator of the gonadotropic axis. Vitamins and Hormones, 77, 285-300. Tena-Sempere, M. (2008b). Ghrelin as a pleotrophic modulator of gonadal function and reproduction. Nature Clinical Practice Endocrinology and Metabolism, 4, 666-674. Wei, C., & Gregory, J.W. (2009). Physiology of normal growth. Paediatrics and Child Health, 19, 236-240.BSE201 STUDY UNIT 5 SU5-14 Solutions or Suggested Answers 1. d) Leptin 2. a) Oestrogen 3. - They undergo puberty later, thereby having 2 additional years to grow before the growth spurt occurs, which results in larger skeletal mass. - Testosterone in males result in increased gains in muscle mass, contributing to greater body mass. 4. a) Greater muscle mass 5. d) All the aboveSTUDY UNIT 6 ACQUISITION AND TRAINING OF SPECIALISED SPORT SKILLSBSE201 STUDY UNIT 6 SU6-1 Chapter 10 Introduction to Motor Learning Learning Outcomes By the end of this Chapter, you should be able to: 1. identify the five general performance characteristics typically observable as motor skill learning occurs 2. describe several methods to assess motor skill learning 3. describe the characteristics of learners as they progress through the stages of learning proposed by (1) Fitts and Posner, and (2) Gentile 4. explain the process of learning new specialised movement skills based on Fitts and Posner's three-stages of skill learning Overview The objective of motor learning is to acquire the ability to perform new movement patterns of a motor skill. Any practitioner working in schools or hospitals would be involved in one way or another to helping an individual learn a new motor skill and assess the progress of learning. More specifically, a physical educator would have the responsibility of instructing and demonstrating new motor skills to children in schools to enable them to gain proficient performance in physical activity and sport. Therefore, it is crucial for physical educators to understand the stages of learning through which learners progress, and be able to assess learning such that appropriate forms of instruction and strategy are used to assist learners to achieve motor proficiency.BSE201 STUDY UNIT 6 SU6-2 10.1 Defining and Assessing Motor Learning 10.1.1 What is Motor Learning? Motor learning is a process in which an individual acquires and refines a motor skill through practice or experience (Coker, 2004; Schmidt & Wrisberg, 2008). Learning of a motor skill is considered to be achieved when there are relatively permanent improvements in an individual's execution of the motor skill, which are attributed to practice or experience. Therefore, in order to assess an individual's motor learning of a skill, the best way is for practitioners to observe the changes in skill execution which occur progressively with practice (Schmidt & Wrisberg, 2008). As individuals learn a motor skill, there are five general performance characteristics which indicate learning: improvement, persistence, consistency, stability, and adaptability (Magill, 2011; Schmidt & Wrisberg, 2008). As mentioned in the definition of learning, there must be improvement in performance of a skill over a period of practice, thereby performing at a higher level. Similarly, persistence is also stated in the definition of learning, with relatively permanent changes in motor performance, with improved performance lasting over a long period of time. As learning occurs, performance of a motor skill gradually becomes more and more consistent, with little variation in performance between attempts. As consistency of performances increases with learning, performance stability should also increase, with external (physical environment) or internal (stress) perturbations having little or no influence on skill performance. Lastly, adaptability is closely linked with performance stability in learning a skill. Performance conditions, such as the weather or place of performance, are always never the same when performing a motor skill, which requires the individual to be able to adapt the skill accordingly to the environmental, tasks or individual demands under which the skill is performed. 10.1.2 Assessing Learning Performance curves One of the most common methods to assess motor learning is through the use of performance curves, which involves recording performance outcomes over the period of time when the individual is practising a skill. The use of performance curves provides information on the improvement and consistency of performance through the shape of the curve. There are four general trends in which learning can be observed through performance curves, namely, linear, negatively accelerated, positively accelerated and S-shaped curves. The linear curve indicates a proportional increase in performance over a period of time. The negatively accelerated curve indicates a rapid improvement in learning in the early stages of practice, and smallerBSE201 STUDY UNIT 6 SU6-3 amounts of improvements at the later stages of practice. The positively accelerated curve on the other hand is the reverse of the negatively accelerated curve, with smaller improvements in performance earlier in practice and larger improvements occurring in the later stages of practice. Lastly, the S-shaped curve is a combination of all three curves (Magill, 2011). Although motor learning has often been assessed and characterised using performance curves, other factors that could influence performance such as motivation, feedback and fatigue are often not considered in the performance outcomes. Therefore, in the attempt to assess actual learning, scientists have implemented the use of transference and retention tests to evaluate the adaptability and the persistence aspect of performance related to motor skill learning. Transference tests are essentially tests that involve a new situation, in which successful performance of the task would require the individual to adapt the skill to the characteristics of the new situation. In such tests, the assessor can alter the physical environment, individual and task aspects of the motor skill. The physical environment can be altered by including a defender while performing a lay-up basketball shot, which demonstrates how an individual is able to adapt to a real game of basketball. Individual aspects of the performer can also be altered by placing the individual in stressful conditions under which the skill is usually performed, thereby also assessing the adaptability and stability of the performer. Finally, the task can be varied to simulate a novel situation to assess the performer's ability to adapt. For example, in the game of golf, putting success can be assessed through the use of different clubs, instead of the club that the performer has been practising with. Retention tests have a similar concept to that of theoretical exams, whereby the performer is assessed on how well they have permanently improved on performing the motor skill after a period of learning. A common way to assess motor skill retention is to assess the skill after a substantial period of time where the skill has not been practised. The amount of skill retention is assessed by the difference in performance outcome at the very initial performance level (on the first practice day) to that of the retention test. The amount of improvement would be an indicator of the extent to which a learner has gained permanency in the motor skill through the practice period.BSE201 STUDY UNIT 6 SU6-4 Consider how you would assess transference and retention of skill in the game of golf and tennis. 10.1.3 Assessing Performance Outcome measures Outcome measures provide the results of an individual's performance on a task, such as the speed (time taken to complete a skill, i.e. 100 m sprint time), accuracy (ability to get as close as possible to the target) and distance (the distance achieved in a long jump or javelin throw). Important to note is that as a practitioner, it is crucial to be able to modify scoring systems according to the performance of learners of different age groups. For example, a young child would perform very differently in the motor skill of catching as opposed to an adolescent. Therefore, the practitioner would need to modify outcome measures in order to evaluate and detect specific aspects of motor skill improvement (Bennett, Button, Kingsbury, & Davids, 1999). Process measures Motor skill performance is not concerned only about the outcome of the performance, but also the quality at which the motor skill is performed. Process measures therefore provide an indication about the quality of the movements performed in the motor skill. Process measures can include simple observational methods or technical laboratory based methods. Simple observational methods are most commonly used by practitioners, in which practitioners would identify important components of the sport and assess how the performer meets the target behaviour most accurately. An example of an observational checklist of the catching skill would include placing the hands and adjusting the body position according to the flight path of the ball, extending the arms to contact the ball, and subsequently absorbing the force of the ball with the hands closing around the ball. In contrast, in a laboratory setting, different methods of assessment can be conducted to qualify movement proficiency. For instruments, three-dimensional movement analysis can be conducted to accurately assess motor performance, together with electromyography which measures muscle electrical activity to determine effective and efficient muscular activity while performing the skill.BSE201 STUDY UNIT 6 SU6-5 10.2 Stages of Learning 10.2.1 Fitts and Posner's Three-Stage Model A popular model presented by Paul Fitts and Michael Posner in 1967 proposed that motor learning can be classified into three stages: the cognitive stage, the associative stage, and the autonomous stage. However, it is important to consider these three stages as a process, in which an individual gradually transitions from one stage of learning to another. The first stage, the cognitive stage of learning, highlights the high degree of cognitive activity required to attend to the task. During this first stage of learning, the learner is introduced to the skill and is attempting to understand the movement's requirements. The additional attentional demands required to receive instructions and feedback add to the cognitive activity of learning the motor skill. Performance during this stage of learning is often marked with large number of errors and inconsistency of movement performance as the learner attempts various techniques/strategies through trial-and-error. In addition, learners at this stage are unable to identify the cause of their errors, and require practitioners to provide instructions and demonstrations in order to correct movement errors. The second stage, the associative stage, is characterised by improved performance, with increased consistency, with fewer and smaller gross errors in movement pattern. The attentional demands of the task required at the cognitive stage decreases as the individual transitions to the associative stage, where the learner begins to be able to adapt and stabilise movement patterns of the skill according to various environmental cues. In addition, the learner is able to detect some of their own movement errors and are more capable of refining and correcting their own movement patterns to improve successful consecutive performance of the motor skill. With these changes in the learning process of the learner, practitioners are encouraged to provide constructive practice experiences which create opportunities for the learner to associate movement patterns with changing environmental cues to promote motor learning. The final stage of the Fitts and Posner's learning model, the autonomous stage, requires many years of practice, before the skill becomes automatic for the performer. In the autonomous stage, the movement patterns are so proficient and habitual that little attention is required to perform the task, therefore not everyone may achieve this stage of learning as stated by Fitts and Posner. Motor skill performance is very consistent from trial to trial, with little variability in performance. In addition, performers commit very few errors, and are very capable of identifying their own movement errors, and are able to make quick adjustments/corrections to perform them successfully. At this stage, it is again important for the practitioner to provideBSE201 STUDY UNIT 6 SU6-6 constructive practice experiences to maintain consistency of performance with varying environmental cues. Additionally, with the high level of proficiency, improvements in performance may be minimal, which makes it important for the practitioner to take on a motivational role in encouraging the performer to achieve excellence. Observe a few children in your PE class performing a specific skill, such as shooting a free-throw or dribbling a basketball. Based on your observation, classify which stage of learning your students are in, and explain why. 10.2.2 Gentile’s Two-Stage Model In contrast to describing the learner's characteristics throughout the learning process as stated by Fitts and Posner, Antoinette Gentile (1972, 1987, 2000) described motor learning to progress through two stages, emphasising the perspective of the goal of the learner as influenced by task and environmental characteristics. In the first stage, which Gentile referred to as the initial stage, the learner is required to achieve two important goals: 1) develop movement coordination patterns that meet the task and environmental conditions in which the skill is to be performed, and 2) be able to discriminate between regulatory and non-regulatory conditions. Firstly, the development of movement coordination patterns is often facilitated or restricted by the regulatory conditions, which are the environmental characteristics associated with the goal of the skill. In other words, to successfully perform a skill, the learner has to coordinate movement patterns to meet the regulatory conditions within its environment. For example, the movement of a goal keeper in intercepting a soccer penalty kick from entering the goal is controlled by the ball's spatiotemporal characteristics. Therefore, in this instance, the movement coordination pattern of the goal keeping is determined by the flight of the ball, in order to achieve the goal of saving the soccer ball. Secondly, for the learner to be able to attend to the appropriate regulatory conditions, he/she must discriminate and identify these regulatory conditions from nonregulatory conditions to enable the formulation of the movement coordination patterns required to perform the skill. Non-regulatory conditions are environmental characteristics that are not associated with the goal of the skill. As such, in the example of the goal keeper saving a penalty kick, the colour of the ball and theBSE201 STUDY UNIT 6 SU6-7 position of the referee are not relevant to the goal of the skill, and therefore do not influence the movements of the goal keeper in performing the interception of the penalty kick. This initial stage of Gentile's two-stage model involves a large amount of problemsolving through repeated trial and error of the learner to be able to effectively identify and process the relevant regulatory conditions that control his/her movements. However, at the end of this stage, although the learner is effective in performing movement patterns that meet the regulatory conditions within its environment, the goal of the skill is not met consistently and even when the goals are met, the movements lack efficiency. Once the learner acquires the basic movement pattern of the skill, he/she progresses to the second stage, which Gentile referred to as the later stages. The later stages require the learner to acquire three general characteristics: 1) adapting, 2) consistency, and 3) economy of effort. Firstly, the learner has to be able to adapt the movement pattern according to the specific needs in any performance conditions. Secondly, the learner has to improve on the consistency in successfully performing the skill. Lastly, the learner must be able to perform the skill with great amount of efficiency, thus optimising the economy of effort. For the learner to attain these three general characteristics, the movement pattern learnt in the initial stage has to be refined and retained or substantially altered depending on the environmental context characteristics (Figure 6.1). As shown in Figure 6.1, closed skills such as performing a gymnastics routine require fixation, which involves the refinement and consistency of movement coordination patterns. With the example of a gymnast, the learner practises the required movement coordination pattern repeatedly in order to "fixate" the skill and perform it consistently with minimal conscious effort and energy. In contrast, open skills are performed in environmental conditions which are highly variable, therefore requiring diversification of the basic movement coordination pattern according to the environmental conditions to achieve the action goal. For example, a soccer player has to be able to diversify the movement coordination pattern of a soccer kick according to his position from goal and the position of the defenders to successfully hit the target.BSE201 STUDY UNIT 6 SU6-8 Figure 6.1 Gentile's two-stage model of learning (Source: Adapted from Coker, 2004) As practitioners, during the initial stage, it is important to provide learners with clear instruction and demonstration of the task to facilitate the learner's development of basic movement coordination pattern. Constant feedback is also important to direct the learner’s visual search for critical regulatory conditions. In the later stages, the strategy applied by the practitioner varies according to the classification of the motor skill. In the practice of a closed skill, practitioners should provide learners with as much practice under the same conditions while introducing non-regulatory conditions such as noise from crowds, fatigue and stress. In the practice of open skills, practitioners should provide as many varying regulatory conditions under which the skill is performed, allowing the learner to respond quickly in modifying movement coordination patterns. You should now read Magill, R.A. (2011). Motor Learning and Control (9th Ed.). New York: McGraw-Hill. Chapter 10 & 11. Initial Stage 1. Development of basic movement pattern 2. Discriminate between regulatory and nonregulatory conditions Later Stages Fixation: Refinement of movement pattern Diversification: Modification of the movement pattern according to the environmental context Closed Skill Open SkillBSE201 STUDY UNIT 6 SU6-9 Chapter 11 Instruction and Augmented Feedback Learning Outcomes By the end of this chapter, you should be able to: 1. distinguish between situations in which demonstration, verbal instruction or both are effective in instructing a learner to perform a new skill 2. relate to examples of how instructions can influence where a person directs his/her attention when performing a skill 3. differentiate between task-intrinsic feedback and augmented feedback 4. compare and contrast qualitative and quantitative augmented feedback 5. demonstrate how augmented feedback can be beneficial or detrimental to skill learning 6. describe the types of augmented feedback that facilitate skill learning Overview The role that a practitioner plays is crucial when an individual is learning a new movement skill. At the initial stages, the practitioner introduces the skill to the learner, through demonstrations and instructions, to provide the learner with a general idea of the movement coordination pattern, as well as assist the learner with discriminating between regulatory and non-regulatory conditions within the environmental context. Furthermore, during the learning process, learners require additional feedback to help with identifying their errors and ways in which they can further improve their technique. Therefore, this chapter aims to provide an overview of the different methods in which practitioners can introduce a variety of movement skills and provide effective feedback that would facilitate the learner in the process of acquiring a new movement skill.BSE201 STUDY UNIT 6 SU6-10 11.1 Demonstration and Verbal Instructions 11.1.1 Demonstration When introducing a novel skill to a learner, visual information in the form of demonstrations are often presented to accompany instructions. Demonstrations are also often referred to as modelling or observational learning, in which modelling involves demonstration for the benefit of the learner, and observational learning involves the learner observing the performance of others to acquire movement information. Theories of learning through observation The most common theory describing the effectiveness of learning through observation is the cognitive mediation theory. The cognitive mediation theory proposed by Bandura (1986) suggests that when a learner observes a skilled performer executing a movement, he/she translates the observed skill into a symbolic memory code, thereby forming a cognitive memory representation of the movement skill. This cognitive representation would subsequently act as a guide for the learner while performing the skill during practice, as well as a reference standard to detect and correct movement patterns (Blandin & Proteau, 2000). As stated by Bandura, four sub-processes direct observational learning: attention, retention, behaviour reproduction and motivation. The attention process is the first important sub-process as it determines what the individual observes and the way he/she perceives the information. In support of this, Ste-Marie (2000) found that participants who had their attention divided during the observation of the movement skill were unable to learn the skill as well as those who had their full attention on observing the skill. The second sub-process, the retention process, is just as important as it plays a crucial role in translating the skill into symbolic memory codes. The cognitive memory representation of the movement skill is then further reinforced through rehearsal, labelling and organisation of the movement skill. The behaviour reproduction process is the third sub-process, in which the learner transforms the cognitive memory representation of the movement skill into physical action, leading to the ability to physically perform the observed skill. The importance of the retention and behaviour reproduction process was further supported by Smyth and Pendleton (1990), where they found that participants who were unable to rehearse the skill were less able to reproduce the movement pattern as compared to those who rehearsed them. Lastly, the motivation process provides the motivation and the incentive to practise and perform the movement skill.BSE201 STUDY UNIT 6 SU6-11 Another perspective on how observation facilitates learning is the dynamic view of modelling as proposed by Scully and Newell (1985).This perspective questions the process required for developing symbolic memory codes to form a cognitive memory representation of the skill. Instead, it proposes that the visual system is sufficient in identifying and processing important coordination patterns of the limbs relative to one another from the demonstration. Therefore, it was suggested that it is most crucial that learners observe demonstrations that allow them to distinguish invariant coordination relationship between various body segments. To test this perspective, Hayes and colleagues (2007) investigated the ability to learn the skill of bowling by observing a video model performing the skill or viewing a point-light display (in which light reflecting material is placed on specific joints of an individual, then filmed in order to only capture the lights reflecting the movement action of the joints). They found that the adults from both the video and point light display were similar in their movement patterns. Interesting to note however is that the pointlight display technique was not as successful in children as compared to adults, with the children being unable to reproduce the movement pattern after viewing the point-light display. Subsequently, it was found that children require additional perception-cognitive training in order to be able to perceive and use the information to reproduce the movement pattern. Designing effective demonstrations As a practitioner, it is important to consider the most effective way in using demonstration to assist in the acquisition of a movement skill. Practitioners should therefore take into account: 1) the content of the demonstration, 2) who the demonstrator should be, 3) the timing at which demonstration should occur, and 4) the frequency at which the demonstrations should occur (Coker, 2004). 1. What specific content should be demonstrated? Coordination vs. control Demonstrations have been found to be effective in enabling a learner to develop new movement coordination patterns as opposed to learning new rhythmical patterns of well-learned patterns. Therefore, initial demonstration should emphasise on the movement pattern (technique) of the skill instead of the control variables. Entire vs. partial As the purpose of a demonstration is to provide the learner with a visual representation of the skill, the entire skill should be performed to enable the learner to perceive the intended skill outcome as well as the invariant coordination relationships between various body parts. However, with complex movementBSE201 STUDY UNIT 6 SU6-12 patterns which can be broken down into segments, for example juggling or breaststroke, after the demonstration of the entire skill, the demonstrator could demonstrate the various parts of the broken down skill. Real time vs. slow motion The purpose of a slow motion demonstration is to focus the learner to specific aspects of the movement skill, however, this fails to provide the general timing and rhythm of the movement coordination pattern. It is therefore suggested that practitioners should firstly perform the skill in its entirety in real time before demonstrating the skill a second time in slow motion while focusing on specific aspects of the stroke. 2. Who should be the demonstrators? Skilled vs. unskilled demonstrators It has been shown that learners perceive invariant features of the movement pattern while viewing a demonstration (Ashford, Bennett, & Davids, 2006; Horn & Williams, 2004). Therefore, it is important that an accurate representation of the skill is provided to assist the learner with developing crucial aspects of the movement skill. Furthermore, by observing a skilled demonstrator, the learner also identifies strategies in which the skilled performer used to solve specific movement problems, and is therefore able to imitate these strategies while learning the skill. However, there are also several benefits by having learners observe other learners or unskilled demonstrators. Research has found that while observing other learners or unskilled demonstrators, the learners observing engage more actively in problem solving. In addition, the learner also benefits from listening to the feedback provided by the practitioner to the unskilled demonstrator, and watching them attempt to correct the movement patterns accordingly. This often results in the ability to perform the skill at a more proficient level than the learners they observed (Hebert & Landin, 1994; McCullagh & Meyer, 1997; Pollock & Lee, 1992). Demonstrator-observer similarity Research has found that learners benefit from observing a demonstrator whom they perceive to be similar to themselves (Gould & Weiss, 1981; McCullagh, 1987). When learners observe an individual whom they can relate to perform the skill successfully, it increases their self-efficacy, motivating them to perform the skill (Gould & Weiss, 1981; McAuley, 1985; Schunk & Hanson, 1985).BSE201 STUDY UNIT 6 SU6-13 3. When should the demonstration be performed? Given that the purpose of performing a demonstration is to provide learners with a general idea of the movement coordination pattern, demonstrations should be performed before the learners practise the skill. However, demonstrations are also beneficial to the learners when interspersed between practices of the skill, as it assists with problems they face while practising the skill (Caroll & Bandura, 1990; Sidaway & Hand, 1992; Weeks & Anderson, 2000). 4. How frequent should the demonstration occur? It is suggested that demonstrations should continue as often as possible during practice (Magill, 2011). Therefore to investigate the timing and frequency of demonstration, Weeks and Anderson (2000) examined the performance outcomes of learners who were presented with different amount of demonstrations, after varying number of practice attempts. It was found that the group that was presented with only demonstrations before practice (30 attempts) and the mixed group that was presented with a few demonstrations at the start and after performing 15 practice attempts, performed better in the retention test as compared with the group that was presented with a single demonstration interspersed with several practice attempts (3 attempts after a single demonstration). Describe how you would implement the use of demonstration in teaching the tennis serve. 11.1.2 Instructions Instructions are another form in which a practitioner can present a skill to a learner. In fact, verbal instructions are often used together with the demonstration in order to guide the learner’s attention to different aspects of the skill. Therefore, for instructions to be effective, it requires the practitioner to provide clear instructions, and direct the learner to focus attention on movement outcomes as well as the regulatory conditions in the environmental context. Amount of information As mentioned in the previous chapter, the first stage of learning in the Fitts and Posner's model is the cognitive stage, which requires a high degree of cognitiveBSE201 STUDY UNIT 6 SU6-14 activity by the learner to attend to the task. Therefore, at this stage of learning, it is important not to overwhelm the learner with excess information. For this reason, practitioners should keep instructions short and clear for them to be effective for learning. Instructions to focus the learner's attention to movement outcomes Often, the purpose of providing instructions is to direct the learner’s attention to either the movement coordination patterns of the skill or the outcome of which the skill is to achieve. These forms of instructions are also known as internal or external foci respectively. Several research studies have therefore investigated the influence of internal and external forms of instruction in acquiring skills in a variety of sport, such as basketball, dart throwing and golf. A popular study used to illustrate the differential effects of internal and external foci was conducted by Wulf and colleagues (1998) using a ski simulator task. They found that the group which had received external focus based instructions (to exert force on the wheel of the simulator platform) performed better and were more skilled in the task as compared to the group that had received internal focus instructions (the way to move their feet). Instructions to focus the learner's attention to regulatory conditions Once again, referring back to the stages of learning according to Gentile's two-stage model, the initial stage is the time where learners gain an understanding of the general idea of the movement performance itself. Subsequently, the later stages involve diversification of the movement coordination pattern according to the regulatory conditions in the environmental context. Therefore, with this in mind, providing information about the regulatory conditions too early during practice may hinder the development of the movement pattern if the learner has yet to achieve a basic movement coordination pattern. A study using a computer-simulated catching task by Green and Flowers (1991) provides a good example of how explicit information of the regulatory conditions may affect performance if provided too early in practice. It was found that the group that had received information about the pathway deviations characteristics (regulatory information) made more errors as compared to the group that had not received any information. Consequently, it was suggested that the additional regulatory information might have overloaded the attentional capacity of the learner, hence detrimental to performance.BSE201 STUDY UNIT 6 SU6-15 11.1.3 Verbal Cues Verbal cues are often used to overcome the problem that may arise when giving too much information during the instruction of the skill. A verbal cue is often a word or a phrase to prompt or direct the learner's attention to specific regulatory conditions in the environmental context, or particular aspects of the movement. For example, the phrase 'look at the ball' focuses the learner's visual attention, and 'raise your hands' cues the learner to raise his/her hands to defend another player. A study by Masser (1993) found that practitioners who provided cues on critical parts of performing a headstand assisted in the acquisition and retention of the skill of those students as compared to those who had not received any performance cues. Similarly, Cutton and Landin (1994) illustrated the benefits of using verbal prompts to guide the learners’ attention to performing key aspects of the skill. In this study, learners were taught to shout five verbal cues each time they were to hit a tennis return, such as "ready", "ball", "turn", "hit" and "head down" to prompt attention and body posture. 11.2 Augmented Feedback Augmented feedback and intrinsic feedback are the two types of feedback that learners receive about their movement performance. Intrinsic feedback is information that is produced by the sensory system (visual, auditory, proprioception and touch) as a response to their movements while performing a skill. Augmented feedback, on the other hand, is information provided from an external source which is additional to that received from the individual's own sensory feedback. Therefore, as a practitioner, it is important to consider how best to provide augmented feedback to ensure effective and efficient motor skill learning of an individual. 11.2.1 Types of Augmented Feedback Augmented feedback can also be further broken down into knowledge of results (KR) or knowledge of performance (KP). KR provides learners with information about their performance outcome of the movement task, or if the goal of the task had been achieved. KR can either be intrinsic or be presented in the form of external feedback. An example of intrinsic KR is when a basketball player shoots a free throw shot and sees the ball bouncing off the board, the player receives visual information that the outcome of the free throw shot had not been achieved. In contrast, when an individual performs a javelin throw, the javelin thrower may not be able to visually determine if the current throw was better than the last. The coach would thenBSE201 STUDY UNIT 6 SU6-16 provide augmented KR to the athlete that he/she had thrown the javelin 5 m beyond his/her personal best. KP is information which is provided to the learner about particular aspects of the movement behaviour which contributed to the outcome of the performance. In the example of the basketball free throw, the coach would provide KP feedback on the aspect of movement which had resulted in the miss, such as "having more flick of the wrist" and "follow through with the fingers". Recently, with improving technology, other methods of providing feedback of KP such as video replay have become increasingly popular. The video replay allows for the learner to associate the coach's feedback with what he/she had done, and be able to mentally envision how to correct his/her movements in the following attempt. 11.2.2 The Roles of Augmented Feedback There are three main roles in the provision of augmented feedback to learners. Firstly, augmented feedback from the coach is targeted to assist the learner to achieve the action goal of the movement skill. The coach would provide information on the aspects on which the movement was performed well, and aspects which were not performed well, thus enabling correction of performance errors by the learner. Secondly, augmented feedback also plays a motivational role in encouraging the learner to continue to achieve the goal of acquiring the skill. During periods of the learning process in which learners struggle with coping with the attentional demands of the task or go through performance plateaus, words of encouragement from the coach help motivate learners to strive onwards to achieve their goals. Lastly, augmented feedback can also help reinforce movement characteristics or learning behaviour during practice to acknowledge a good performance, or effortful attempts. Whether or not augmented feedback is effective in achieving its goal in assisting skill acquisition depends on the nature of the skill and the individual learning the skill. Augmented feedback is essential to learning when learners do not receive any intrinsic feedback, or are unable to perceive the intrinsic feedback to improve movement performance characteristics and rely solely on augmented feedback to correct and reinforce performance. In some cases, due to the nature of the motor skill, augmented feedback may not be critical to learning, however, it aids in the speed of learning and the proficiency of skill performance. For example, skills that are complex and involve inter-limb coordination, augmented feedback can help increase the rate at which the skill is learnt and maintain learning at a higher proficiency than if augmented feedback was not provided. The basketball free throw shot is an example of such a skill, in which augmented feedback has been shown to improve the rate and level of skill acquisition (Wallace & Hagler, 1979), although acquisition of the skill is achievable through repeated attempts.BSE201 STUDY UNIT 6 SU6-17 Augmented feedback may also not be necessary, or might even hinder skill acquisition, as intrinsic feedback received by the individual is sufficient for learning. This usually occurs when individuals over rely on augmented feedback instead of perceiving and understanding the intrinsic feedback received by the sensory systems. In addition, inaccurate augmented feedback, poor timing of feedback and the high frequency of feedback may also contribute to the detrimental effects of providing augmented feedback. 11.2.3 Content of Augmented Feedback Error vs. correct feedback A frequent dilemma of practitioners is whether the content of augmented feedback should consist of informing individuals of their errors, or reinforcing aspects of which the individual performed well. Therefore, to determine the content of the feedback, practitioners should ask themselves of the purpose in which they are providing the feedback. If practitioners are focused on improving the acquisition of the skill, augmented feedback should comprise mainly error based feedback to point out the errors in which the learner has made. This error based feedback in these situations would encourage the learner to self-correct errors, which would also assist the acquisition and transference of the skill in different environmental conditions. However, correct feedback also plays an important role in reinforcing correct movement patterns, thus motivating an individual in the learning process. KP vs. KR Another frequent question that practitioners ask themselves is the type of augmented feedback, KR or KP, that they should provide to their learners. Although studies have shown KP has been more commonly used and effective in facilitating skill acquisition (Kernodle & Carlton, 1992; Zubiaur, Ona, & Delgado, 1999), the use of KR also has its purposes. KR facilitates skill acquisition by: 1) providing learners with verification of their own performance outcomes with their own intrinsic feedback, 2) providing the results of their performance when intrinsic feedback is not available, 3) motivating learners as results improve, and 4) encouraging learners to employ in a problem-solving approach.BSE201 STUDY UNIT 6 SU6-18 KP, on the other hand, facilitates skill acquisition when: 1) motor skills involve specific movement coordination patterns, 2) specific aspects of movement performance requires correction, and 3) intrinsic feedback is sufficient for KR. Descriptive vs. prescriptive use of KP In providing learners with KP, feedback can either be descriptive or prescriptive in nature. Often, the stage at which the learner is at determines which form to use. In the initial stages of learning, a prescriptive nature of feedback is more beneficial to learning as it prescribes to the learner what he/she should do in order to achieve a certain movement outcome. In addition, descriptive feedback is only useful when the learner is able to associate the described movement with a specific motor behaviour, which may be employed as the learner gets more proficient. However, appropriate use of both descriptive and prescriptive use of feedback could facilitate the learner to relate between their movement errors and the correction of those movements. Qualitative vs. quantitative Referring back to Gentile's two-stage model of learning, the initial stage involves the learner gaining a general idea of the movement pattern. With this in mind, learners in the initial stages of learning have been suggested to benefit more from qualitative feedback, where the quality of movement performance is provided without accurate, numerical, quantitative information. Quantitative feedback, however, becomes more beneficial when the goal of the learner is to refine and improve on the outcome of the movement skill performance. In the acquisition of archery and gymnastics, what different types of feedback would you provide to your students in each of these skills? 11.2.4 Timing of Augmented Feedback Augmented feedback can be provided either concurrently with performance or terminally at the end of the performance. Most often, terminal augmented feedback is provided throughout the learning process. However, concurrent feedback can beBSE201 STUDY UNIT 6 SU6-19 beneficial for learning especially when no intrinsic feedback is available for the learner. Another concern is with regards to the timing of when terminal augmented feedback is presented. Knowledge of results (KR)-delay interval is the delay in which terminal feedback is given after the performance of the skill. It has been initially suggested that terminal feedback should be presented immediately after performance of the skill, despite the limited research to support it. On the other hand, research investigating the effect of performing other forms of activity during this time interval on skill acquisition has shown that it can either be detrimental, beneficial or non-influential. Most interesting to note is that when the individual is involved with evaluating his/her own performance before providing terminal augmented feedback, it has been shown to be beneficial to learning. This activity in evaluating one's own performance allows the individual to estimate the outcome of his performance, or/and estimate the movement characteristics of his performance, which is later either reinforced or corrected by the terminal augmented feedback received. Another common consideration for practitioners is when the next attempt should be performed following terminal augmented feedback, also known as post-KR interval. It has been suggested that the post-KR interval provides the learner with time to process the terminal augmented feedback together with the intrinsic feedback that they received while performing the skill, as well as integrate that feedback as the individual plans his/her movements in the following attempt. Depending on the complexity of the movement skill, the duration of these intervals may vary to provide sufficient time to process and plan for the next attempt. In addition, practitioners should also encourage and assist with the learner’s understanding of the feedback to facilitate learning. 11.2.5 Frequency of Augmented Feedback Similar to the use of demonstrations, it is often thought that for optimal learning, feedback should be provided as frequently as possible, to help guide the learning process of the individual, also known as the guidance hypothesis. However, the provision of feedback after every attempt has been suggested to overload the learner, or cause the learner to over-rely on augmented feedback, leading to a lack of processing his/her own motor performance (Salmoni, Schmidt, & Walter, 1984; Schmidt, Young, Swinnen, & Shapiro, 1989; Winstein, Pohl, & Lewthwaite, 1994). As a result, there has been several methods in which practitioners can employ to assist in the frequency of providing augmented feedback.BSE201 STUDY UNIT 6 SU6-20 Bandwidth feedback Bandwidth feedback is a technique used by practitioners to determine when to provide feedback. A bandwidth is initially predetermined by the practitioner at which a range of performance outcome/characteristic is considered correct and hence feedback is not provided. As such, learners at the very initial stage would most often receive frequent feedback on performance, but as learning occurs, and performance improves, the frequency of feedback also decreases. In addition, this technique would also provide positive reinforcements on motor behaviour which falls within the performance bandwidth (Smith, Taylor, & Withers, 1997). Summary and average feedback In both summary and average feedback, augmented feedback is provided after the learner completes a certain number of trials. In summary feedback, specific augmented feedback is provided for every single trial that was performed. Average feedback, on the other hand, consists of augmented feedback that provides information about the average performance across all trials. Both the use of summary and average feedback techniques have been shown to result in better learning as opposed to feedback after every trial (Young & Schmidt, 1992). You should now read Magill, R.A. (2011). Motor Learning and Control (9th Ed.). New York: McGraw-Hill. Chapter 14 & 15.BSE201 STUDY UNIT 6 SU6-21 Chapter 12 Practice Conditions Learning Outcomes By the end of this chapter, you should be able to: 1. comment on the use of practice variability in skill learning 2. relate to situations in which contextual learning benefits motor skill learning 3. demonstrate how overlearning in different situations can be beneficial or detrimental to learning motor skills 4. discuss the relationship between overlearning and other practice condition variables 5. compare and contrast massed and distributed intertrial interval schedules for discrete and continuous motor skills 6. discuss how the complexity and organisation of a complex motor skill influence the implementation of whole or part practice 7. demonstrate ways in which part practice methods of fractionalisation and segmentation can be applied to the practice of motor skills Overview In the learning of a new motor skill, depending on the nature of the skill, it may take the learner many days or years to acquire the skill. Therefore, practitioners play a very important role in the scheduling of practice conditions to facilitate this learning process for learners. In designing the practice session, the practitioner has to consider three important aspects. Firstly, the practitioner has to consider how best to help the learner be able to perform the skill which is retainable and transferable across time and conditions, by providing practice under varying conditions. Secondly, the practitioner has to consider how long and frequent practice sessions should be to facilitate learning, taking into consideration the rest intervals between practice sessions. Lastly, the practitioner has to determine how best to practise the skill, depending on the skills complexity and organisation. Therefore, this chapter aims to guide the practitioner through these important factors that he/she needs to consider before implementing the practice sessions.BSE201 STUDY UNIT 6 SU6-22 12.1 Practice Variability When we consider the performance of any skill, there is no one time when all conditions remain the same. Therefore, when structuring practice sessions, it is important to consider how practice conditions facilitate the learner to adapt to the variability that he/she face while performing the motor skill. Practice variability is therefore a way in which practitioners overcome these issues by providing a variety of environmental contexts and movement characteristics for the learner to practise a skill. Looking back to the first chapter of this unit, learning can be assessed using retention and transfer tests. Much research has shown that practice variability encourages learners to actively engage in problem solving through trial and error. Although the variability of practice conditions results in increased errors in performance during practice sessions, these errors have been proposed to develop an individual's schema to coordinate movement (Schmidt, 1975). As a result, the learner is able to adapt movement coordination according to the various contextual requirements of the skill, as assessed in transfer and retention tests. A research commonly used to illustrate the benefits of practice variability is that of Shea and Kohl (1991) who investigated the learners’ ability to squeeze a hand dynamometer at 150 Newtons of force, after a period of constant or variable practice strategies. The constant group practised the applying at force of 150 Newtons, whereas the variable practice group practised applying varying forces except 150 Newtons during the practice sessions. Following practice, it was found that the learners in the constant practice group performed poorer in applying a 150 Newton force (retention test) as compared to the variable group who performed a transfer test, applying a force of 150 Newtons, of which had not been practised. 12.1.1 Implementing Practice Variability To know how best to implement practice variability, a practitioner has to consider the environmental context (regulatory and non-regulatory conditions) in which the skill would be performed, as well as the nature of the skill, whether it is an open or closed skill. While performing skills in which regulatory conditions affect movement characteristics, it is important for practitioners to provide a variety of similar conditions during practice, to enable learners to adapt performance behaviour of the skill. Non-regulatory conditions, on the other hand, may affect the ability of the learner to transfer the skill between practice sessions and actual assessment of performance or tests. Non-regulatory conditions such as noise, crowd or fatigue may influence the ability of the learner to perform. Therefore, practice sessions shouldBSE201 STUDY UNIT 6 SU6-23 also include a variety of non-regulatory characteristics to maintain consistent performance between one environmental context and another. As mentioned, an important element of consideration is the nature of the skill. In the context of a closed skill, it is important to consider if the skill involves inter-trial variability. For closed skills that do not involve inter-trial variability, non-regulatory conditions is likely to influence performance of the skill, and hence a variety of nonregulatory conditions should be provided during practice. However, if the closed skill involves inter-trial variability, practice providing a variety of both regulatory and non-regulatory conditions would be beneficial for skill acquisition. In the performance of an open skill, every performance is unique, which means that the learner has to adapt his/her movement coordination characteristics frequently according to the regulatory conditions in the environmental context to successfully perform the skill. Therefore, in implementing practice variability in the practice of an open skill, the practitioner would need to provide a variety of experiences by altering the regulatory conditions to enable the learner to quickly adapt and respond accordingly. It is also important for practitioners to know when would be an appropriate time in the learning process to implement practice variability. As with Fitts and Posner's and Gentile's stages of learning, the initial stages involve the learner acquiring the general movement coordination pattern of the skill. Therefore, during this period, it is best for the practitioner to provide constant practice in which it reduces the cognitive requirements as well as builds the learner's confidence. Subsequently, as the learner progresses, the practitioner would want to consider implementing the relevant practice variability conditions to promote skill acquisition. 12.1.2 Contextual Interference In the process of organising practice variability, depending on how the practice session is arranged, there are different amounts of contextual interference. Contextual interference is the disruption of memory and performance that occurs as a result of switching between performing multiple skills or the context in which variations of the skill is performed. Contextual interference is low when practice of one variation a skill is performed repeatedly before the practice of a different variation of the skill (blocked practice). On the other hand, when multiple variations of the skill are performed in random order (with no two same variations in succession of each other), also known as random practice, there is a high amount of contextual interference.BSE201 STUDY UNIT 6 SU6-24 According to traditional view of interference, low contextual interference would actually facilitate learning, whilst high contextual interference would hinder the learning process. Contrary to this view, William Battig (1979) demonstrated that a high amount of contextual interference is in fact beneficial for learning, as it encourages the learner to process the skill in the various conditions, thereby facilitating retention and decreasing his/her dependence on memory and instruction. In addition, the extent to which contextual interference is implemented induces the use of processing strategies for learning, hence facilitating the transfer of the motor skill across conditions. Accordingly, the facilitation of learning through practising variations of the skill through high amounts of contextual interference as compared to repeated practice of the same variation of the skill in low contextual interference is known as the contextual interference effect. The first research to support the contextual interference effect was by Shea and Morgan (1979). In this study, participants learned three motor tasks with low contextual interference (blocked), or high contextual interference (random). Retention of the task was assessed under the same practice conditions 10 minutes post and 10 days post practice. They found that in accordance to Battig's contextual interference effect, retention of the task was better in the group that experienced high interference learning as compared to low interference learning group. In addition, transfer of the task was also assessed, and similar to the results from the retention test, transfer of the skill was better facilitated through high interference practice than low interference practice. Limitations of the contextual interference effect Characteristic of the motor skill To date, the main limitation of the contextual interference effect is that most of the studies examining retention and transfer involved laboratory based skills, which tend to be simpler and more easily acquired as compared to actual sport based motor skills. In these laboratory based studies, it has been suggested that high contextual interference is more effective when the skills being acquired are more dissimilar than similar. However, in the applied setting, contextual interference that involves skill variations that are more similar have been found to promote skill acquisition. This notion is supported by Landin and Hebert (1997) where high contextual interference involving distance and angles at which a one-handed basketball set shot was performed, leads to greater skill acquisition, as compared to the acquisition of three different volleyball skills (French, Rink, & Werner, 1990). If we were to consider applied sport based skills, they tend to be more complex in terms of the movement coordination pattern, thereby requiring more practice to acquire the skill as compared to laboratory based skills which may only involveBSE201 STUDY UNIT 6 SU6-25 movement of the upper limb. Furthermore, according to Gentile's two-stage learning model, the main goal of the initial stage is to develop a basic movement pattern of the skill. Therefore, this may require a progression from low to high amounts of contextual interference to promote the basic movement pattern, before introducing higher amounts of contextual interference to facilitate their ability to discriminate between regulatory and non-regulatory conditions. However, further research is required to better support the implementation of contextual interference by practitioners in sport settings. Learner characteristics Age and skill level of the learners are most likely to limit the contextual interference effect on skill acquisition. Given that the initial stages of learning involve high degrees of cognitive processing, the high amounts of contextual interference may overload learners who are young in age, thereby hindering the skill learning process (Brady, 1998). Similarly, low amounts of contextual interference have been found to facilitate skill acquisition in novices as compared to skilled-individuals (Del Rey, Whitehurst, & Wood, 1983; Hebert, Landin, & Solomon, 1996; Landin & Hebert, 1997). Practical implications Given the above limitations in the use of contextual interference, it is therefore important that as a physical educator these limitations are considered in the teaching of sport skills to young children. Firstly, with the learning of new skills in young children, physical educators should employ practice schedules that involve low contextual interference (blocked practice) to enable the learner to gain a basic movement pattern of the skill. Subsequently, the physical educator should progress to a moderate level of contextual interference by implementing repeated-blocked practice. Repeated blocked practice is a combination between blocked and random practice, whereby instead of performing 10 soccer kicks at each of 5 locations (blocked), the physical educator can instruct the learner to perform 5 soccer kicks at each location and rotating around for 2 sets. This moderate contextual interference would facilitate the learner to engage in higher processing strategies as well as to be able to discriminate between regulatory and non-regulatory conditions. Finally, as proficiency of the skill improves, the practice session should involve varied aspects of the skill as high contextual interference nonetheless results in better retention and transfer of the skill.BSE201 STUDY UNIT 6 SU6-26 12.2 The Amount and Distribution of Practice 12.2.1 The Amount of Practice As a practitioner, it is important to determine the amount of time required for an individual to learn a motor skill. Therefore, many research studies have investigated the impact that the amount of practice has on the ability to successfully perform a motor skill, when the amount of practice is more than what is needed to achieve the performance criterion (also known as overlearning). Theoretically, overlearning provides two benefits: 1) it reinforces the response processes required to perform the skill, and 2) it provides the individual with greater stability in the control of movement coordination patterns of the skill. Given that each and every motor skill has its distinct characteristics, overlearning may have different effects on the acquisition of different skills. Magill (2011) differentiated the effect of overlearning on procedural skills, dynamic balance skills and physical educational classes. Research examining the impact of overlearning on procedural skills (assembling a gun), found that overlearning by performing a 100% more trials was beneficial to skill retention 8 weeks post training (Schendel & Hagman, 1982). However, when it came to dynamic balance skills and physical educational classes, there was a point where overlearning resulted in a plateau in skill acquisition. In other words, groups that performed 50% more trials than required performed as well as the group that had performed 100% and 200% more trials, thereby suggesting that beyond a certain amount of overlearning, the benefits is not relatively proportionate in the retention tests (Goldberger & Gerney, 1990; Melnick, 1971). 12.2.2 The Distribution of Practice In addition to the amount of practice, another important consideration for a practitioner is how to structure the practice of the motor skill, in terms of the amount of rest learners require in between practice trials. With regards to the distribution of practice, researchers have investigated to determine if few but long practice sessions with short rest intervals (massed practice) or more but short sessions with long rest intervals are better (distributed practice). Although there hasn't been much research comparing the effects of massed and distributed practice, most of these research have indicated that distributed practice may result in better learning (Baddely & Longman, 1978). In a more recent study, Shea and colleagues (2001) found that spacing practice sessions across days resulted in increased skill acquisition as compared to spacing practice sessions within a day.BSE201 STUDY UNIT 6 SU6-27 This may be an advantage to the physical educators as physical education classes are structured in a way that promotes distributed practice. Magill (2011) proposed three explanations for the benefits of employing distributed practice. Firstly, fatigue during massed practice sessions negatively impacts learning, especially when the skill being practised requires alertness and muscular endurance. Secondly, massed practice results in reduced cognitive effort by the learner, which is important for skill acquisition when needing to discriminate regulatory and nonregulatory conditions. Lastly, distributed practice promotes memory consolidation process, which transforms a temporary/unstable memory representation of the skill into a more stable and permanent one (similar to that of the cognitive mediation theory). Practice distribution for continuous and discrete skills Despite the benefits found for the use of distributed practice, researchers have proposed that optimal benefits of learning depend on the type of skill being learned (continuous or discrete). It has been suggested that distributed practice leads to better skill acquisition as compared to massed practice for continuous motor skill (Lee & Genovese, 1988), whereas massed practice benefitted the acquisition of discrete skills better than distributed practice (Carron, 1969; Lee & Genovese, 1988, 1989). Describe how you would schedule your practice sessions when teaching the skill of (1) archery, and (2) rock climbing. 12.3 Whole and Part Practice Whole and part practice has been an issue of debate in the use of teaching a skill to a learner either as a whole skill or in parts before putting the skill together. When learning a novel skill, being able to simplify the skill and practise it in parts may facilitate the learning process as it provides learners with success early during the learning of the skill, and allows the learner to work on difficult aspects of the skill without having to practise other aspects of the skill in which the learner is proficient in.BSE201 STUDY UNIT 6 SU6-28 12.3.1 Skill Complexity and Organisation It wasn't till the 1960's where Naylor and Briggs (1963) were able to determine the use of either whole or part practice depending on the complexity and organisation of the skill. Skill complexity refers to the number of components as well as the information processing demands of the skill. Therefore, the greater the number of components, and the greater amount of attentional demand required, the more complex the skill (i.e. serving a tennis ball). In contrast, a low complex skill involves little components and requires little attention, such as picking up a cup. Skill organisation on the other hand refers to the relationships that exist between the different components of the skill. If one component of the skill is dependent on the spatial and temporal aspects of the previous component, the skill is considered to be high in organisation. For example, the cascade juggling is an example of a highly organised skill where each component is dependent on the component that precedes it. On the other hand, tapping one’s hands according to a rhythm is considered to be low in skill organisation as the components of the skill are not dependent of each other. According to Naylor and Briggs, it is most important to firstly determine the complexity and organisation of the skill before determining whether to use part or whole practice. If the skill is low in organisation but high in complexity, the skill would best be practised in parts, such as practising the breaststroke arms and the kick separately, and putting them together once the individual components have achieved a certain level of proficiency. However, if a task is high in organisation but low in complexity, practising the skill as a whole is more beneficial, such as throwing a dart. However, when the skill is high in both organisation and complexity, it is important for the practitioner to analyse the skill and determine which components of the skill are interdependent and dependent of each other. This would enable the practitioner to decide how best to break the skill into parts that can be practised independently. 12.3.2 Part Practice Techniques In deciding to implement the use of part practice, there are also different methods in which the practitioner can apply the part practice. The three different ways in which a skill can be broken down into parts are through fractionisation, segmentation and simplification.BSE201 STUDY UNIT 6 SU6-29 Fractionisation Fractionisation involves the breaking down of a skill which involves asymmetric coordination of the arms or legs into practising of the individual limbs first before practising the skill as a whole. Examples of skills which would fall into this method of part practice would include the tennis serve, the sidestroke and playing of musical instruments. It has however been questionable if fractionisation would be the best way to practise asymmetrical rhythmic skills, as these skills require a high degree of organisation, which may be best practised as a whole (Kurtz & Lee, 2003). Segmentation Segmentation involves breaking down the skill into parts according to its spatial or temporal elements, and practising the first part, and once that is practised, practising the second part, first separately, then together with the first part, and so on (also known as the progressive part method). A good example of a skill which can be practised using the segmentation method is the breaststroke in swimming. The learner first practises the arm and the leg action separately before practising them together to coordinate the timing of the arms and the legs. The greatest benefit of practising a skill using the segmentation method is the ability to practise the skill first as parts, and also as a whole, thus reducing the amount of attentional demands required if the skill were practised firstly as a whole. This method is therefore beneficial for skills that are high in skill complexity, and moderate in skill organisation. Simplification The simplification method is to reduce the difficulty of parts of the skill or the whole skill to facilitate learning. Practitioners can apply this method of simplification through a number of ways. One way is to modify the objects to reduce the difficulty of the task. Catching in young children can be practised by using scarves to help them develop the ability to visually track the object and catch it. Another way is to reduce the attentional demands of the skill by providing physical assistance or additional tools to assist the initial practice of the skill. For example, in learning to strike a softball, assistance can be provided by practising the striking of the ball on a tee, thereby making the open skill more closed first. A third way is to reduce the speed at which the skill is practised. For example, the volleyball serve can be practised at a slower speed to establish the movement coordination pattern first, before varying the speed at which the entire skill is performed. The fourth method is to provide additional auditory cues that assist with the rhythmic coordination of the skill. Although this method of simplification adds a component to the practice of the skill, the additional auditory cues play a role inBSE201 STUDY UNIT 6 SU6-30 pacing the movements of the individual according to the spatiotemporal requirements of the skill. The fifth method involves sequencing skill progressions and practising the skill in progressive difficulty. For example, with the striking of a softball, the skill is made less complex by hitting the ball off the tee places at the same height. The practice is then progressively made more difficult by adjusting the tee to different heights, and finally practising the strike with the ball being thrown. In the last method, simulators and virtual reality technology is used to simulate the environment to facilitate practice. It has become increasingly popular for these forms of technology to be used in the practice of a skill. Through the use of simulators and virtual reality, the regulatory and non-regulatory conditions can be controlled to practise certain conditions for a longer period to ensure proficiency before increasing the complexity of the skill. You should now read Magill, R.A. (2011). Motor Learning and Control (9th Ed.). New York: McGraw-Hill. Chapter 16, 17 & 18.BSE201 STUDY UNIT 6 SU6-31 Quiz 1. Which is not a stage of learning in Fitts and Posner's three stage model? a) Autonomous b) Retention c) Cognitive d) Associative 2. Which one of the following is not a characteristic of motor learning? a) Improvement b) Persistence c) Variability d) Stability 3. Which one of the following sub-processes in Bandura's observational learning theory might be most influenced by model characteristics of the demonstrator? a) Retention b) Motivation c) Behaviour reproduction d) Attention 4. Which of the following would best describe the skill of performing a jump serve in volleyball? a) Low in complexity, low in organisation b) Low in complexity, high in organisation c) High in complexity, low in organisation d) High in complexity, high in organisation 5. By practising striking the ball off a tee with a larger softball bat, which method of simplification has been employed? a) Reducing attentional demands b) Modification of object c) Sequencing skill progression d) All of the aboveBSE201 STUDY UNIT 6 SU6-32 Summary In the process of acquiring a new skill, learners progress through different stages of learning. In Chapter 10, we discussed two models through which a learner progresses from a beginner to a skilled performer. The first is the Fitts and Posner's three-stage model whereby learners transition from the cognitive stage, associative stage and lastly to the autonomous stage. Each of these stages is classified according to the performer’s characteristics, such as the attentional demand and the ability to identify and correct errors. In contrast, the Gentile's two-stage model classifies learning according to the performance characteristics, which are controlled by regulatory conditions of the environmental context. For a practitioner to classify the learner in the appropriate stage of learning, there is a need for the practitioner to assess learning of the particular motor skill through transference tests and retention tests and evaluating the performance curves. With understanding of the progression of motor learning, the practitioner would therefore be able to apply appropriate teaching strategies to improve skill acquisition of the learner. In Chapter 11, we have reviewed the different methods which practitioners use to introduce a new skill to learner, and the use of feedback during the learning process to aid skill acquisition. However, for practitioners to effectively use demonstration, instruction and cues in the presentation of a skill, it is important to implement them appropriately according to the individual skills, and when in the stage of learning to use it. Augmented feedback is also a common form of feedback to provide learners with information to facilitate their learning process. Depending on the nature of the skill, and whether intrinsic feedback is available, augmented feedback may or may not be effective in guiding the learner. Therefore, practitioners also need to be aware of the situations in which feedback is required, and how best to reduce the amount of feedback as the learner progresses in the acquisition of the skill. Having reviewed the three factors that practitioners should consider in view of the nature of the skills, as well as the learning process according to Fitts and Posner's and Gentile, initial practice should facilitate the acquisition of the basic movement coordination pattern. Therefore, initial practice should include low amounts of contextual interference, with massed practice and where possible practised in parts. Subsequently, as the learner improves in the skill performance, higher amounts of contextual interference and whole practice should be performed. However, the practitioner would need to discern the optimal timing at which practice of the skill should be changed in order to facilitate learning in each individual performer.BSE201 STUDY UNIT 6 SU6-33 References Ashford, D., Bennett, S.J., & Davids, K. (2006). Observational modelling effects for movement dynamics and movement outcome measures across differing task constraints: A meta-analysis. 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