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Tóm tắt nội dung (trích từ tài liệu gốc): BIOMECHANICAL EVALUATION OF MOVEMENT IN SPORT AND EXERCISE Biomechanical Evaluation of Movement in Sport and Exercise offers a com- prehensive and practical sourcebook for students, researchers and practitioners involved in the quantitative evaluation of human movement in sport and exercise. This unique text sets out the key theories underlying biomechanical evaluation, and explores the wide range of biomechanics laboratory equipment and software that is now available. Advice concerning the most appropriate selection of equipment for different types of analysis, as well as how to use the equip
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BIOMECHANICAL EVALUATION OF MOVEMENT
IN SPORT AND EXERCISE
Biomechanical Evaluation of Movement in Sport and Exercise offers a com-
prehensive and practical sourcebook for students, researchers and practitioners
involved in the quantitative evaluation of human movement in sport and
exercise.
This unique text sets out the key theories underlying biomechanical evaluation,
and explores the wide range of biomechanics laboratory equipment and
software that is now available. Advice concerning the most appropriate
selection of equipment for different types of analysis, as well as how to use
the equipment most effectively, is also offered.
The book includes coverage of:
� Measurement in the laboratory and in the field
� Motion analysis using video and on-line systems
� Measurement of force and pressure
� Measurement of muscle strength using isokinetic dynamometry
� Electromyography
� Computer simulation and modelling of human movement
� Data processing and data smoothing
� Research methodologies
Written and compiled by subject specialists, this authoritative resource provides
practical guidelines for students, academics and those providing scientific
support services in sport science and the exercise and health sciences.
Carl J. Payton is Senior Lecturer in Biomechanics at Manchester Metropolitan
University, UK. Roger M. Bartlett is Professor of Sports Biomechanics in the
School of Physical Education, University of Otago, New Zealand.
BIOMECHANICAL EVALUATION OF
MOVEMENT IN SPORT AND EXERCISE
The British Association of Sport and
Exercise Sciences Guidelines
Edited by Carl J. Payton and Roger M. Bartlett
First published 2008
by Routledge
2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN
Simultaneously published in the USA and Canada
by Routledge
270 Madison Ave, New York, NY 10016
This edition published in the Taylor & Francis e-Library, 2007.
"To purchase your own copy of this or any of Taylor & Francis or Routledge's
collection of thousands of eBooks please go to www.eBookstore.tandf.co.uk."
Routledge is an imprint of the Taylor & Francis Group, an informa business
� 2008 Carl J. Payton and Roger M. Barlett, selection and editorial matter;
individual chapters, the contributors
All rights reserved. No part of this book may be reprinted or
reproduced or utilised in any form or by any electronic, mechanical,
or other means, now known or hereafter invented, including photocopying
and recording, or in any information storage or retrieval system,
without permission in writing from the publishers.
British Library Cataloguing-in-Publication Data
A catalogue record for this book is available from the British Library
Library of Congress Cataloging in Publication Data
Biomechanical evaluation of movement in sport and exercise: the British
Association of Sport and Exercise Science guide / edited by Carl Payton and
Roger Bartlett.
p. ; cm.
Includes bibliographical references.
ISBN 978-0-415-43468-3 (hardcover) � ISBN 978-0-415-43469-0 (softcover)
1. Human mechanics. 2. Exercise�Biomechanical aspects.
3. Sports�Biomechanical aspects. I. Payton, Carl. II. Bartlett, Roger.
III. British Association of Sport and Exercise Sciences.
[DNLM: 1. Movement�physiology. 2. Biometry�methods.
3. Exercise�physiology. 4. Models, Statistical. WE 103 B6139 2007]
QP303.B557 2007 2007020521
612.7 6�dc22
ISBN 0-203-93575-6 Master e-book ISBN
ISBN10: 0-415-43468-8 (hbk)
ISBN10: 0-415-43469-6 (pbk)
ISBN10: 0-203-93575-6 (ebk)
ISBN13: 978-0-415-43468-3 (hbk)
ISBN13: 978-0-415-43469-0 (pbk)
ISBN13: 978-0-203-93575-0 (ebk)
CONTENTS
List of tables and figures vii
Notes on contributors xiii
1 Introduction 1
ROGER M. BARTLETT
2 Motion analysis using video 8
CARL J. PAYTON
3 Motion analysis using on-line systems 33
CLARE E. MILNER
4 Force and pressure measurement 53
ADRIAN LEES AND MARK LAKE
5 Surface electromyography 77
ADRIAN BURDEN
6 Isokinetic dynamometry 103
VASILIOS BALTZOPOULOS
7 Data processing and error estimation 129
JOHN H. CHALLIS
8 Research methods: sample size and variability effects on
statistical power 153
DAVID R. MULLINEAUX
9 Computer simulation modelling in sport 176
MAURICE R. YEADON AND MARK A. KING
vi CONTENTS
Appendix 1: The British Association of Sport and Exercise
Sciences�code of conduct 207
Appendix 2: On-line motion analysis system manufacturers and
their websites 213
Index 215
TABLES AND FIGURES
TABLES
5.1 Summary of amplifier characteristics for commercially
available electromyography systems 81
5.2 Summary of sensor characteristics for commercially
available electromyography systems 84
6.1 Summary of the range or limits of angular velocities and
moments under concentric and eccentric modes for the
most popular commercially available isokinetic
dynamometers, including manufacturer website
information 118
7.1 Ten measures of a reference length measured by a motion
analysis system throughout the calibrated volume 131
8.1 Research design, statistics and data factors affecting
statistical power 155
8.2 Statistical analyses available for quantifying variability and,
consequently coordination, in two or more trials, across
the entire cycle or as an overall measure for the entire
cycle. The examples relate to three trials of a healthy, male
participant running at 3 m s-1 (see Figures 8.1 to 8.7) 170
FIGURES
2.1 (a) High-speed video camera (Photron Fastcam Ultima
APX) capable of frame rates up to 2000 Hz at full
resolution (1024 � 1024 pixels); (b) Camera Processor unit 12
2.2 Apparent discrepancy in the lengths of two identical rods
when recorded using a camera-to-subject distance of 3 m
(image a) and 20 m (image b). Note that the rods are being
held shoulder width apart 19
viii TABLES AND FIGURES
2.3 Distortion of angles when movement occurs outside the
plane of motion. The true value of angles A and B is 90
(image a). In image b, angle A appears to be greater than
90 (A ) and angle B appears to be less than 90 (B ), as
the frame is no longer in the plane of motion 20
2.4 The effect of camera frame rate on the recording of a
football kick. At 50 Hz (top row) the foot is only seen in
contact with the ball for one image; at 250 Hz (middle
row) the foot remains in contact for four images; at
1000 Hz (bottom row) the foot is in contact for sixteen
images (not all shown) 23
2.5 Calibration frame (1.60 m � 1.91 m � 2.23 m) with 24
control points (Peak Performance Technologies Inc.) 25
2.6 Calibration frame (1.0 m � 1.5 m � 4.5 m) with 92 control
points (courtesy of Ross Sanders) 25
3.1 (a) The L-frame used in the static calibration of a motion
capture system and its relationship to the laboratory
reference frame; (b) The wand used in the dynamic
calibration 39
3.2 Marker sets used in on-line motion analysis: (a) Standard
clinical gait analysis marker set; (b) Cluster-based
marker set 43
3.3 Different ways of presenting the same multiple-trial
time-normalised kinematic data: (a) mean curve; (b) mean
� 1 standard deviation curves; (c) all individual curves.
The example shown is rear-foot motion during running 49
4.1 Force (or free body diagram) illustrating some of the forces
(contact, C, gravity, G and air resistance, AR) acting on
the runner 54
4.2 The force platform measurement variables 55
4.3 The three component load cells embedded at each corner
of the force platform 56
4.4 Typical force data for Fx, Fy, Fz, Ax, Az and My for a
running stride 63
4.5 Typical graphical representation of force variables (Fx, Fy,
Fz, Ax and Az). Note that My is not represented in this
format 65
4.6 Free body diagram of a person performing a vertical jump 67
4.7 Derived acceleration, velocity and displacement data for the
vertical jump. Units: force (N); acceleration (m s-2) � 70;
velocity (m s-1) � 700; displacement (m) � 1000 68
4.8 Plantar pressure distribution measurements inside two
soccer boots during landing from a maximal jump in the
same participant. Higher pressures under the ball of the
forefoot (towards the top of each pressure contour map),
where studs are located, are experienced while using
boot A 70
TABLES AND FIGURES ix
5.1 An EMG signal formed by adding (superimposing) 25
mathematically generated motor unit action potential
trains (from Basmajian and De Luca, 1985) 78
5.2 The influence of electrode location on EMG amplitude.
(a) Eight electrodes arranged in an array, with a 10 mm
spacing between each electrode. The lines (numbered 1
to 8) above the array indicate the different combinations of
electrodes that were used to make bi-polar recordings.
Inter-electrode distances are 10 mm for pairs 1, 2 and 3;
20 mm for pairs 4 and 5; 30 mm for pair 6; 40 mm for
pair 8; and 50 mm for pair 7. (b) EMGs recorded using the
array shown in (a) when placed on the skin overlying the
biceps brachii at 70 per cent of MVC (adapted by Enoka,
2002 from Merletti et al., 2001) 85
5.3 (Top) EMG signal amplitude and force during an
attempted constant-force contraction of the first dorsal
interosseus muscle. (Bottom) Power spectrum density of
the EMG signal at the beginning (a) and at the end (b) of
the constant force segment of the contraction (from
Basmajian and De Luca, 1985) 96
6.1 The application of a muscle force F (N) around the axis of
rotation (transmitted via the patellar tendon in this
example) with a position vector r relative to the origin.
This generates a muscle moment M (N m) that is equal to
the cross product (shown by the symbol �) of the two
vectors (r and F). The shortest distance between the force
line of action and the axis of rotation is the moment arm
d(m). is the angle between r and F. M is also a vector
that is perpendicular to the plane formed by F and r
(coming out of the paper) and so it is depicted by a
circular arrow 104
6.2 Schematic simplified diagram of the main components of
an isokinetic dynamometer 106
6.3 Schematic simplified diagram of the feedback loop for the
control of the angular velocity by adjusting the resistive
moment applied by the braking mechanism of the
dynamometer. The resistive moment exerted against the
limb depends on whether the actual angular velocity of the
input arm is higher or lower compared to the user selected
target (pre-set) angular velocity 106
6.4 Free body diagrams of the dynamometer input arm (left)
and the segment (right) for a knee extension test. Muscle
strength is assessed by estimating the joint moment MJ
from the dynamometer measured moment MD 107
6.5 The definition of a moment (bending moment). Force
vector and moment are perpendicular to the long
structural axis 109
x TABLES AND FIGURES
6.6 The definition of a torque (twisting moment) and the
twisting effect. The axis of rotation is aligned with the long
structural axis and the force pair is causing the torque. The
torque vector is in line with the long structural axis and
the axis of rotation 110
6.7 Moment and angular velocity during a knee extension test
with the pre-set target velocity set at 5.23 rad s-1
(300 deg s-1). Notice that the maximum moment was
recorded when the angular velocity was just under
4 rad s-1 during the deceleration (non-isokinetic)
period 111
6.8 Gravitational moment due to the weight of the segment
(FGS) acting with a moment arm dG around the axis of
rotation of the joint. Since the gravitational force FS is
constant, the gravitational moment will depend on dG and
will be maximum at full extension and zero with the
segment in the vertical position (90 of knee flexion in this
example) 113
6.9 Effects of misalignment of axes of rotation. The axes of
rotation of the segment and dynamometer input arm are
not aligned and, in this case, the long axes of the segment
and input arm are not parallel either. Because the segment
attachment pad rotates freely and is rigidly attached to the
segment, the force applied by the segment (FS) is
perpendicular to its long axis but not perpendicular to the
dynamometer input arm. As a result, only a component
(FSX) of the applied force FS is producing a moment
around the axis of rotation of the dynamometer 114
6.10 An example of dynamometer and joint axis of rotation
misalignment. In this case, the long axes of the segment
and input arm are parallel (coincide in 2D) so the force
applied by the segment FS is perpendicular to the input
arm but the moment arms of the forces FS and FR relative
to the dynamometer (rd = 0.28 m) and joint (rs = 0.3 m)
axis of rotation, respectively, are different. As a result, the
joint moment (MJ) and the dynamometer recorded moment
(MD) are also different 115
6.11 At high target velocities the isokinetic (constant angular
velocity) movement is very limited or non-existent. In this
test with the target velocity preset at 5.23 rad s-1
(300 deg s-1), the isokinetic phase lasts only approximately
0.075 s, and is only about 15 per cent of the total
extension movement. Moment data outside this interval
should be discarded because they do not occur in isokinetic
(constant angular velocity) conditions and the actual
angular velocity of movement is always slower than the
required pre-set velocity 124
TABLES AND FIGURES xi
7.1 Three possible permutations for accuracy and precision,
illustrated for shots at the centre of target. (a) High
accuracy and high precision. (b) Low accuracy and high
precision. (c) Low accuracy and low precision 132
7.2 Illustration of the influence of sample rate on reconstructed
signal, where `o' indicates a sampled data point 134
7.3 A signal with frequency components up to 3 Hz is sampled
at two different rates, and then interpolated to a greater
temporal density 135
7.4 The performance of two filtering and differentiating
techniques, autocorrelation procedure (ABP) and
generalised cross-validated quintic spline (GCVQS), for
estimating acceleration data from noisy displacement data
using criterion acceleration data of Dowling, 1985 141
7.5 Example of quantisation error, where the resolution only
permits resolution to 1 volt 147
7.6 Graph showing the rectangular parallelepiped which
encompasses all possible error combinations in variables x,
y and z 149
8.1 Angles for knee (solid lines) and hip (dashed lines) for
three trials of a healthy, male participant running at
3 m s-1. In the anatomical standing position, the knee is at
180 (flexion positive) and the hip is at 0 (thigh segment
to the vertical; flexion positive; hyper-extension negative).
Key events are right foot contact at 0% and 100%, and
right foot off at 40% 166
8.2 Ratio of the hip to the knee angles for three trials of a
healthy, male participant running at 3 m s-1 (left axis), and
using the mean score as the criterion the RMSD of these
three trials (right axis). First 40% is right foot stance
phase 166
8.3 Knee�hip angle-angle diagram for three trials of a healthy,
male participant running at 3 m s-1. Heel strike ( ), toe
off (�) and direction (arrow) indicated
167
8.4 Coefficient of correspondence (r) determined using vector
coding (Tepavac and Field-Fote, 2001) of three trials of the
knee�hip angle-angle data for a healthy, male participant
running at 3 m s-1. The coefficient ranges from maximal
variability (r = 0) to no variability (r = 1). First 40% is
right foot stance phase 167
8.5 Phase-plane of the knee (solid lines) and hip (dashed lines)
angles for three trials of a healthy, male participant
running at 3 m s-1. Angular velocity is normalised to the
maximum value across trials (hence 0 represents zero
angular velocity), and angle is normalised to the range
within trials (i.e. -1 represents minimum, and +1
represents maximum value) 168
xii TABLES AND FIGURES
8.6 Continuous relative phase between the hip and knee angles
of three trials of a healthy, male participant running at
3 m s-1. Phase-plane angle () used in the range of
0 180. First 40% is right foot stance phase 168
8.7 Continuous relative phase standard deviation (CRP-sd) in
the three CRP angles between the hip and knee angles for
three trials of a healthy, male participant running at
3 m s-1. First 40% is right foot stance phase 169
8.8 Quantification of variability in hip and knee angles for
three trials of a healthy, male participant running at
3 m s-1 using vector coding (�), RMSD ( ) and continuous
relative phase standard deviation (no symbol) for, when in
the anatomical standing position, the hip is 0 (solid lines)
and hip is 180 (dashed lines). Note, vector coding does
not change with the hip angle definition. First 40% of time
is the right foot stance phase 171
9.1 Free body diagram of a two-segment model of a gymnast
swinging around a high bar 183
9.2 Comparison of performance and simulation graphics for
the tumbling model of Yeadon and King, 2002 189
9.3 Free body diagram for a four-segment model of a
handstand 192
9.4 Four-segment model of a handstand 194
9.5 Joint torque obtained by inverse dynamics using six
equation system and nine equation over-determined system.
(Reproduced from Yeadon, M.R. and Trewartha, G.,
2003. Control strategy for a hand balance. Motor
Control 7, p. 418 by kind permission of Human Kinetics) 195
9.6 Knee joint torque calculated using pseudo inverse dynamics
and constrained forward dynamics 196
NOTES ON CONTRIBUTORS
Vasilios (Bill) Baltzopoulos is a Professor of Musculoskeletal Biomechanics at
the Manchester Metropolitan University. His main research interests focus on
joint and muscle-tendon function and loading in both normal and pathological
conditions, measurement of muscle strength and biomechanical modelling and
processing techniques.
Roger M. Bartlett is Professor of Sports Biomechanics in the School of Physical
Education, University of Otago, New Zealand. He is an Invited Fellow of the
International Society of Biomechanics in Sports (ISBS) and European College of
Sports Sciences, and an Honorary Fellow of the British Association of Sport and
Exercise Sciences, of which he was Chairman from 1991�4. Roger is currently
editor of the journal Sports Biomechanics.
Adrian Burden is a Principal Lecturer in Biomechanics at Manchester Metropoli-
tan University where he is also the Learning & Teaching co-ordinator in
the Department of Exercise and Sport Science. His main interests lie in the
application of surface electromyography in exercise, clinical and sport settings,
and he has run workshops on the use of electromyography for the British
Association of Sport and Exercise Sciences.
John H. Challis obtained both his B.Sc. (Honours) and Ph.D. from
Loughborough University of Technology. From Loughborough he moved to the
University of Birmingham (UK), where he was a lecturer (human biomechanics).
In 1996 he moved to the Pennsylvania State University, where he conducts
his research in the Biomechanics Laboratory. His research focuses on the
coordination and function of the musculo-skeletal system, and data collection
and processing methods.
Mark A. King is a Senior Lecturer in Sports Biomechanics at Loughborough
University. His research focuses on computer simulation of dynamic jumps,
subject-specific parameter determination, racket sports and bowling in
cricket.
xiv NOTES ON CONTRIBUTORS
Mark Lake is currently a Reader in Biomechanics at Liverpool John Moores
University. His research interests lie in the area of lower limb biomechanics
during sport and exercise with investigations of basic lower extremity function
as well as applied aspects relating to sports footwear and injury prevention. He
acts as a consultant for several sports shoe manufacturers and is a member of
the International Technical Group for Footwear Biomechanics.
Adrian Lees is Professor of Biomechanics and Deputy Director of the Research
Institute for Sport and Exercise Sciences. His research interests cover both sport
and rehabilitation biomechanics. He has a particular interest in sport technique
and its application to soccer and the athletic jump events. He is Chair of the
World Commission of Sports Biomechanics Steering Group for Science and
Racket Sports. He has also developed and conducted research programmes into
wheelchair performance and amputee gait.
Clare E. Milner is an Assistant Professor in the Exercise Science Program of
the Department of Exercise, Sport, and Leisure Studies at the University of
Tennessee, where she specializes in biomechanics. Her research interests focus
on the biomechanics of lower extremity injury and rehabilitation, in particular
the occurrence of stress fractures in runners and the quality of walking gait
following joint replacement surgery.
David R. Mullineaux is an Assistant Professor at the University of Kentucky,
USA. He has made several transitions between academia and industry gaining
experience of teaching, consulting and researching in biomechanics and research
methods in the UK and USA. His research interest in data analysis techniques
has been applied to sport and exercise science, animal science, and human and
veterinary medicine.
Carl J. Payton is a Senior Lecturer in Biomechanics at Manchester Metropolitan
University. He is High Performance Sport Accredited by the British Association
of Sport and Exercise Sciences. His research and scientific support interests are
in sports performance, with a particular focus on the biomechanics of elite
swimmers with a disability.
Maurice R. (Fred) Yeadon is Professor of Computer Simulation in Sport at
Loughborough University. His research interests encompass simulation, motor
control, aerial sports, gymnastics and athletics.
CHAPTER 1
INTRODUCTION
Roger M. Bartlett
BACKGROUND AND OVERVIEW
This edition of the `BASES Biomechanics Guidelines', as they have become
almost affectionately known, is an exciting development for the Association,
being the first edition to be published commercially. Many changes have taken
place in sports biomechanics since the previous edition (Bartlett, 1997) a decade
ago. Not only have the procedures used for data collection and analysis in
sport and exercise biomechanics continued to expand and develop but also the
theoretical grounding of sport and exercise biomechanics has become sounder,
if more disparate than formerly.
The collection and summarising of information about our experimental
and computational procedures are still, as in earlier editions (Bartlett, 1989;
1992; 1997), very important and we need continually to strive for standardis-
ation of both these procedures and how research studies are reported so as to
enable comparisons to be made more profitably between investigations. Most
of the chapters that follow focus on these aspects of our activities as sport and
exercise biomechanists.
Carl Payton covers all aspects of videography, usually called video analysis
in the UK, in Chapter 2. One major change since the previous edition of these
guidelines is that cinematography has been almost completely supplanted by
videography, despite the considerable drawbacks of the latter particularly in
sampling rate and image resolution. Automatic marker-tracking systems have
become commonplace in sport and exercise biomechanics research, if not yet
in our scientific support work because of the need for body markers and the
difficulty of outdoor use. This is reflected in a complete chapter (Chapter 3),
contributed by Clare Milner, covering on-line motion analysis systems, whereas
they were covered in an `odds and ends' chapter in the previous edition. I find
this new chapter one of the easiest to read in this volume, a tribute to the author
as the subject matter is complex.
2 ROGER M. BARTLETT
Image-based motion analysis remains by far and away the most important
`tool' that we use in our work. Important and up-to-date chapters cover
other aspects of our experimental work. Adrian Lees and Mark Lake report
on force and pressure measuring systems (Chapter 4), Adrian Burden on
surface electromyography (Chapter 5), and Vasilios Baltzopoulos on isokinetic
dynamometry (Chapter 6). With the loss of the general chapter of the previous
edition, other experimental aspects of biomechanics that are peripheral to sport
and exercise biomechanics do not feature here. Multiple-image still photogra-
phy has vanished both from the book and from our practice; accelerometry
fails to appear, although it is increasingly used by other biomechanists, mainly
because it is a very difficult technique to use successfully in the fast movements
that dominate sport; electrogoniometry is not here either as we do not often
use it.
In these empirically based chapters, the authors have sought to include an
introduction and rationale for the data collection techniques and a discussion
of equipment considerations. They have also tried to provide practical, bullet-
pointed guidelines on how to collect valid, reliable data and practical advice
on how to process, analyse, interpret and present the collected data. Finally,
they include bullet-pointed guidelines on what to include in a written report,
and follow-up references.
John Challis contributes an important chapter on data processing and
error estimation (Chapter 7) and David Mullineaux one on research design
and statistics (Chapter 8). One of the most appealing and inventive aspects of
this book is the inclusion of a `theoretical' chapter; Maurice (`Fred') Yeadon
and Mark King's chapter (Chapter 9) on computer simulation modelling in
sport is an important step forward for this book.
WHAT SPORT AND EXERCISE BIOMECHANISTS DO
The British Association of Sport and Exercise Sciences (BASES) accredits
biomechanists in one of two categories: research and scientific support services.
Sport and exercise biomechanists also fulfil educational and consultancy roles.
These four categories of professional activity are outlined in the following sub-
sections and broadly cover how we apply our skills. Not all sport and exercise
biomechanists are actively involved in all four of these roles; for example, some
of us are accredited by BASES for either research or scientific support services
rather than for both.
Research
Both fundamental and applied research are important for the investigation
of problems in sport and exercise biomechanics. Applied research provides
the necessary theoretical grounds to underpin education and scientific support
services; fundamental research allows specific applied research to be developed.
Sport and exercise biomechanics requires a research approach based on a
INTRODUCTION 3
mixture of experimentation and theoretical modelling. Many of the problems
of the experimental approach are outlined in Chapters 2 to 8.
Scientific support services
It is now undoubtedly true that more sport and exercise biomechanists in the
UK provide scientific support services to sports performers and coaches, and
clients in the exercise and health sector, than engage in full-time research. In this
`support' role, we biomechanists use our scientific knowledge for the benefit
of our clients. This usually involves undertaking a needs analysis to ascertain
the client's requirements, followed by the development and implementation of
an intervention strategy. First, we seek to understand the problem and all of
its relevant aspects. Then the appropriate qualitative or quantitative analytical
techniques are used to deliver the relevant scientific support: in scientific support
work, these are far more often qualitative than quantitative, although this is not
reflected in the contents of this book. Sport and exercise biomechanists then
provide careful interpretation of the data from our analyses, translating our
science into `user friendly' terms appropriate to each problem and each client.
Increasingly, this scientific support role for sport and exercise biomechanists
has a multi-disciplinary or inter-disciplinary focus. This may involve the person
concerned having a wider role than simply biomechanics, for example by also
undertaking notational analysis of games as a performance analyst or advising
on strength and conditioning. It may also involve biomechanists working
in inter-disciplinary teams with other sport and exercise scientists, medical
practitioners or sports technologists.
Education
As educators, sport and exercise biomechanists are primarily involved in
informing the widest possible audience of how biomechanics can enhance
understanding of, for example, sports performance, causes of injury, injury
prevention, sport and exercise equipment, and the physical effects of the
environment. Many people benefit from this education, including coaches and
performers at all standards, teachers, medical and paramedical practitioners,
exercise and health professionals, leisure organisers and providers, national
governing body administrators and the media.
Consultancy
A demand also exists for services, usually on a consultancy basis, from sport
and exercise biomechanists, scientists or engineers with detailed specialist
knowledge, experience or equipment. This arises, for example, in relation to
sport and exercise equipment design or injury diagnostics. The procedure for
obtaining such services normally involves consultation with an experienced
sport and exercise biomechanist in the first instance.
4 ROGER M. BARTLETT
ANALYSIS SERVICES
Sport and exercise biomechanists offer various types of analysis to suit the needs
of each application and its place in the overall framework of biomechanical
activities. These can be categorised as qualitative or quantitative analysis as
follows.
Qualitative analysis
Qualitative analysis has become more widely used by sport and exercise
biomechanists as our role has moved from being researchers to being involved,
either partly or as a full-time occupation, in a scientific support role with
various clients in sport and exercise, including sports performers and coaches.
Some of us have also, along with new theoretical approaches to our disci-
pline such as dynamical systems theory, started to reappraise the formerly
narrow concept of what qualitative analysis involves (for a further discussion
of these new approaches in the context of an undergraduate textbook,
see Bartlett, 2007).
Qualitative analysis is still used in teaching or coaching to provide
the learner with detailed feedback to improve performance and, in the
context of analysing performance, to differentiate between individuals when
judging performance, in gymnastics for example. It is also used in descriptive
comparisons of performance, such as in qualitative gait analysis. Qualitative
analysis can only be provided successfully by individuals who have an excellent
understanding of the specific sport or exercise movements and who can
liaise with a particular client group. Such liaison requires a positive, ongoing
commitment by the individuals involved. Although qualitative analysis has
been seen in the past as essentially descriptive, this has changed with the
increasing focus on the evaluation, diagnosis and intervention stages of the
scientific support process, and may change further with new interpretations
of the movement patterns on which the qualitative analyst should focus
(Bartlett, 2007).
Quantitative analysis
The main feature of quantitative analysis is, naturally, the provision of quantita-
tive information, which has been identified as relevant to the sport or exercise
activity being studied. The information required may involve variables such
as linear and angular displacements, velocities, accelerations, forces, torques,
energies and powers; these may be used for detailed technical analysis of a
particular movement. Increasingly, sport and exercise biomechanics are looking
at continuous time-series data rather than discrete measures. Furthermore, we
study movement coordination through, for example, angle-angle diagrams,
phase planes and relative phase, often underpinned by dynamical systems
theory; hopefully, by the next edition of this book, these approaches will be
sufficiently developed and standardised to merit a chapter.
INTRODUCTION 5
Many data are often available to the sport and exercise biomechanist,
so that careful selection of the data to be analysed is required and some data
reduction will usually be needed. The selection of important data may be based
on previous studies that have, for example, correlated certain variables with
an appropriate movement criterion; this selection is greatly helped by previous
experience. The next stage may involve biomechanical profiling, in which a
movement is characterised in a way that allows comparison with previous
performances of that movement by the same person or by other people. This
obviously requires a pre-established database and some conceptual model of
the movement being investigated.
Good quantitative analysis requires rigorous experimental design and
methods (Chapter 8). It also often requires sophisticated equipment, as dealt
with in Chapters 2�6. Finally, an analysis of the effects of errors in the data is
of great importance (Chapter 7).
PROCEDURAL MATTERS
Ethics
Ethical principles for the conduct of research with humans must be adhered
to and laboratory and other procedures must comply with the appropriate
code of safe practice. These issues are now addressed by the BASES Code of
Conduct (Appendix 1). Most institutions also have Research Ethics Committees
that consider all matters relating to research with humans. Ethical issues
are particularly important when recording movements of minors and the
intellectually disadvantaged; however, ethical issues still arise, even when video
recording performances in the public domain, such as at sports competitions.
Pre-analysis preparation
It is essential for the success of any scientific support project that mutual
respect exists between the client group and the sport and exercise scientists
involved. The specific requirements of the study to be undertaken must be
discussed and the appropriate analysis selected. In qualitative studies using
only video cameras, it is far more appropriate to conduct filming in the natural
environment, such as a sports competition or training, instead of a controlled
laboratory or field setting. Decisions must also be made about the experimental
design, habituation and so on.
Any special requirements must be communicated to the client group well
beforehand. Unfamiliarity with procedures may cause anxiety, particularly at
first. This will be most noticeable when performing with some equipment
encumbrance, as with electromyography or body markers for automatic-
tracking systems, or in an unfamiliar environment such as on a force platform.
Problems can even arise when there is no obvious intrusion, as with video,
if the person involved is aware of being studied. This problem can only
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[Cuối tài liệu]
APPENDIX 2
ON-LINE MOTION ANALYSIS
SYSTEM MANUFACTURERS
AND THEIR WEBSITES
Charnwood Dynamics www.charndyn.com
Elite Biomechanics www.bts.it
Motion Analysis Corporation www.motionanalysis.com
Northern Digital Inc. www.ndigital.com
Peak Performance Technologies www.peakperform.com
Qualisys Medical AB www.qualysis.com
Skill Technologies Inc. www.skilltechnologies.com
Vicon Motion Systems www.vicon.com
INDEX
Accuracy: definition 130�1 Computers: force platforms, and 58;
Action-reaction principle 57 processing EMGs, and 89; specification
Analysis services 4�5; qualitative analysis 4; for video recording 15�16
quantitative analysis 4�5 Confidentiality 6
Angles: defining 143 Consultancy 3; biomechanists' role 3
Angular velocity: isokinetic dynamometry, Co-ordination: measuring 169
Cross-correlation 87
110�12 Cross-talk: electromyography, and 87�8
Anteroposterior direction of motion 62
Automatic marker-tracking systems 1; Data analysis: electromyograms 98; isokinetic
dynamometry 123�6; on-line systems 47�8
outdoor use, and 1
Average Rectified Value (ARV) 89 Data collection: electromyography, 83�9 see
also Surface electromyography; in-shoe 72;
Biomechanists: analysis services 4�5; on-line systems, using see On-line systems;
consultancy 3; education 3; research 2�3; pressure distribution measurements 72;
role 2�3; scientific support services 3 video, using, 17�28 see also Video
Body segment inertia data 10 Data dredging 33
Body segment inertial parameters 138�9 Data logger system 80; electromyography,
British Association of Sport and Exercise
and 80
Sciences: Code of Conduct 207�12; Data processing 129�52; body segment inertial
competence 209�10; confidentiality 209;
data protection 209; disciplinary procedures parameters 138�9; computation of
211�12; ethical clearance 208; informed derivatives 139�43; definition of key terms
consent 208�9; officers 210; professional 130�3; electromyograms 98; error
and personal conduct 210; structure 208 estimation, and 129�52; force and pressure
data 74; force plates 145�7; four stages of
Calibration: error estimation, and 129; force analysis 129; image-based motion analysis
platforms 61�2; isokinetic dynamometry 136�8; isokinetic dynamometry 123�6; joint
119�20; on-line systems see On-line systems; angles 143�5; low-pass filtering 139�43;
pressure distribution measurements 70; on-line systems 46�7; sampling time series
simultaneous multi-frame analytical data 133�6; segment orientation 143�5;
calibration 136; wand calibration 136 variables and parameters 147�9
Data reduction 48
Cameras see On-line systems; Video Derivatives: computation of 139�43; low-pass
Cardanic angle convention 144�5 filtering, and 139�43; signal derivatives
Cinematography 8 139�40
Cleaning data 46 Detailed reporting 6�7; confidentiality 6;
Computational procedures: standardisation 1 guidelines 6; need to standardise 6;
Computer simulation modelling 176�205; publication 6�7; research, and 6�7
Digital filters 139, 140
applications 197�8; control of sports Direct Linear Transformation algorithm
movements 199; forward dynamics problem 24, 136
see Forward dynamics problem; inverse
dynamics problem 191�7; reporting studies Education 3; biomechanists' role, and 3
199�200; study, conducting 199 Electrodes 83
216 INDEX
Electromyography see Surface Isokinetic dynamometry 103�28; angular
electromyography acceleration of rotating segment 103�4;
applications 103, 104�5; data collection
Ensemble averaging EMGs 92�3 procedures 119�23; equipment
Error estimation 129�52 see also Data considerations 117�19; human movement
103; isokinetic parameters 124�6; main
processing; force plates 145�7; joint factors affecting measurements 110�17;
angles 143�5 meaning 103; mechanical basis of
Estimation: sample size, of 155�9 measurements 105�17; muscle and joint
Ethics 5; conduct of research, and 5 function 104�5; muscle strength 104;
Eulerian system 145 processing, analysing and presenting data
Experimental procedures: standardisation 1 123�6; reporting studies 126
Filtering 47; low-pass 139�43 see also Isometric MVC Method 93; criticisms of 94
Low-pass filtering
Joint angles 143�5; segment orientation,
Force plates 145�7; meaning 145 and 143�5
Force platform 53�68; accuracy of data, and
Joint function assessment 104�5
59; action-reaction principle 57; applications Joint kinetics 68; force platforms, and 68
61�8; background and history 53�5;
calibration 59�60; centre of pressure Kinematic variables 28�9; calculating 28�9
co-ordinates 60; computing kinematics 66�8; Kinematics: computing from force
construction and operation 55�7; dead
weight, application 59�60; derived variables data 66�8
65�6; dynamic 60; external force 57; force
diagram 54; friction force 62; general Landmarks: motion analysis, and 137
operation 61; identity of axis 57; interaction Lanshammer formulae 141�2;
of forces 53; internal joint kinetics 68;
interpretation of force variables 61�2; load assumptions 142
cell 56; Marey's force measuring device 54; Linear Envelope 90�1
operating conditions 59; reaction forces 56; Linked segment models 178�9
reporting studies 73; strain gauge platform Low-pass filtering 139�43; amount of 140;
55; technical specification 57�9; variables
measured 55�6; vertical force axis, of 61 categories of 139; computation of
Force and pressure measurement 53�76; derivatives, and 139�43; recommendations
knowledge of forces 53; pressure 143; reduction of noise 139
distribution measurements, 69�73, see also
Pressure distribution measurements; Marker sets see On-line systems
processing data 74; reporting studies 73�4 Mediolateral force 62
Forward dynamics problem 177�91; issues in Model building, 177 see also Forward
model design 190�1; model building 177�8;
model components 178�80; model dynamics problem
construction 182�5; model evaluation Monitors, computer 16
188�90; muscle models 180�2; parameter Motion analysis: data processing 136�8;
determination 185�8
Frequency domain: processing EMGs in 95�7 landmarks 137; on-line systems, using see
Frequency domain techniques 139 On-line systems; reconstruction accuracy
Functional tests 87 136�8; video, using see Video
Motor unit 77
Gen-lock 14 Movement patterns: analysis 8
Gravity correction: isokinetic dynamometry Multiple trials: analysing 163�4; variability,
and 163�4
121�2 Multiplexing techniques 71
Muscle fibres 77
HDV video format 11 Muscle function assessment 104�5
High jumping: relationship between speed and Muscle models 180�2
Muscle strength 104
jump height 176
Noise 132�3; definition 132�3; low-pass
Inertia parameters 186 filtering, and 139; random 133;
Innervation ratio 77 systematic 133
Interpretation, of data: force variables 61�2;
Non-linear transformation technique 136
on-line systems 48�50; Normalising: EMGs 93�5; offset normalisation
Inverse dynamics 9�10; computational
162�3; ratio normalisation 159�62
procedures 9; interpretation of results 10; Nyquist Theorem 88
limitations to approach 10
Inverse dynamics problem, 191�7 see also Offset normalisation 162�3
Computer simulation modelling On-line systems 33�52; acceptable residual,
determination 40; application 33;
INDEX 217
calibration 39�41; camera lens settings 36; Sample size: estimating 155�9
camera redundancy 35; camera sensitivity Sampling time series data 133�6; sample
40; capture volume 36; data analysis 47�8;
data collection procedures 35�46; data duration 135�6; sampling theorem 133�4
interpretation and presentation 48�50; data Scientific support services 3
processing 46�7; data reduction 48; `dead Segment orientation 143�5; joint angles,
space' 37�8; discrete variables 48�50;
dynamic calibration 41; equipment and 143�5
considerations 34�5; focus on injury 33; Shannon's sampling theorem 133�4;
hardware set-up 35�8; laboratory-fixed
global axes 39; maintenance of valid interpolation formula 135
calibration 41; manufacturers' websites 213; Shoe design: evaluation 69
marker sets 41�6; marker system 34; motion Signal processing: force platforms, and 60�1
analysis using 33�52; number of cameras Simultaneous multi-frame analytical
34�5; placement of cameras 37; reporting
study 50�2; sampling rate 38; static calibration 136
calibration 40; stray reflections 40; Skin: preparation for electromyography 86
synchronisation of hardware 38; video Software: isokinetic dynamometry,
analysis compared 8�9
Orthotics 69 for 117�18; video capture 16
Splines 139
Parameter determination: simulator models, Sports technique: optimisation of 198
for 185�8; Statistics 153�5; estimating sample size 155�9;
Parameters: combination of variables and `power' 154�5; `statistical rareness' 153;
147�9; uncertainties 147 `statistical significance testing' 153�4;
variability see Variability
Pre-analysis preparation 5�6; familiarity with Strength parameters 187
procedures 5�6; requirements of study 5 Surface electromyography 77�102; amplifier
characteristics 80�3; Average Rectified Value
Precision: definition 131�2 (ARV) 89; clinical 79; `clipping' 88;
Presentation, of data: isokinetic dynamometry cross-correlation 87; cross-talk 87�8; data
collection procedures 83�9; data logger
123�6; on-line systems 48�50; video motion system 80; differential amplifiers 83, 86;
analysis 29 electrode configuration 83�6; electrode gel
Pressure distribution measurements 69�73; 86; electromyography, meaning 77;
calibration curve 70; in-shoe data collection ensemble averaging EMGs 92�3; equipment
72; low sample rate 71; multiplexing considerations 80�3; frequency domain,
techniques 71; range of signal 69�70; processing in 95�7; functional tests 87;
reporting studies 74; sensor arrays 69; hardwired systems 80; indwelling electrodes
spatial resolution 72; temperature, effect 73; 78; Isometric MVC Method 93�4;
transducers 69 kinesiological 79; Linear Envelope 90�1;
Pressure measurement see Force and pressure location of electrodes 83�6; moving average
measurement approach 90; normalising EMGs 93�5; peak
amplitude 80; processing, analysing and
Qualitative analysis 4 presenting EMGs 89�97; reporting studies
Quantitative analysis 4�5 97�8; Root Mean Square EMG (RMS)
89�90; sampling 88�9; signal detected 77;
Ratio normalisation 159�62 skin preparation 86; threshold analysis
Reconstruction algorithms 24 91�2; time domain, processing in 89�91
Reporting studies: computer simulation
Three-dimensional video recording
modelling 199�200; electromyographical see Video
studies 97�8; force platform 73; isokinetic
dynamometry 126; on-line motion analysis Threshold analysis 91�2; electromyograms,
study 50�2; pressure sensing arrays 74; and 91�2
research methods 171�2; video motion
analysis 30 Time domain: processing EMGs in 89�91
Research 2�3; biomechanists' role, and 2�3; Time-series data 153; analysing variability in
detailed reporting 6�7; ethics, and 5
Research methods 153�75; estimating sample 164�71 see also Variability
size 155�9; reducing variability 159�64 see Two-dimensional video recording
also Variability; reporting studies 171�2;
stages 153; statistical power 153�5 see also see Video
Statistics; time-series data 153
Resolution: definition 132 Variability: analysing in time-series data
Root Mean Square EMG (RMS) 89�90 164�71; analysing multiple trials 163�4;
Rotation alignment 113�16 discrete values 165; kinematic data 164�5;
offset normalisation 162�3; ratio
normalisation 159�62; reducing 159�64
Variables: assessment of influence of 148;
combining 147�9; extraction of discrete
48�50; force 65�6
218 INDEX
Vertical support force 61 space (performance volume) 24; on-line
Video: advances in technology 8; advantages motion analysis compared 8�9; optical zoom
range 12; picture quality 11�12; pixels 11;
over cine film 8; alignment of playback system 16�17; position of cameras
performance 26�7; analysis of movement 26; qualitative 9; quantitative 9;
patterns 8; body landmarks 26; cameras reconstruction accuracy 136�8;
10�15; capture software 16; compatibility reconstruction algorithms 24; recording and
issues 11; control points 26; co-ordinate storage device 15�16; recording medium 15;
digitiser 17; data 28�9; data collection reporting video motion analysis study 30;
procedures 17�28; equipment considerations resolutions 11�12; selection of 10; shutter
10�17; equipment set up 24�7; event speed 13; shutter synchronisation 27;
synchronisation 27; features 10; Firewire smoothing and transforming co-ordinates
connections 15; frame rate (sampling 28; three-dimensional video recording 24�7;
frequency) 12�13; gen-lock capability 14; tripod 26; two-dimensional video recording
global co-ordinate system 26�7; HDV 11; 18�23; video digitising 27�8; world
high-speed cameras 13; high speed shutter standards 11
13�14; kinematic variables 28�9; lens 12; Viscoelastic parameters 187�8
low-light sensitivity 14; manual iris 14;
manual shutter speed 13; motion analysis Wand calibration 136
using 8�32; multiple cameras 24; Wobbling masses: modelling, and 179
non-coplanar control points 24�5; object