ROLE OF LENGTH SPECIFICITY, VELOCITY SPECIFICITY AND ... · berbanding kekuatan isometrik selepas...
Transcript of ROLE OF LENGTH SPECIFICITY, VELOCITY SPECIFICITY AND ... · berbanding kekuatan isometrik selepas...
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ROLE OF LENGTH SPECIFICITY, VELOCITY SPECIFICITY AND NEURAL
ADAPTATIONS IN STRENGTH TRAINING
By
AHMAD NAIM ISMAIL
Thesis submitted to the School of Graduate Studies, Universiti Putra Malaysia, in
Fulfilment of the Requirements for the Degree of Doctor of Philosophy
March 2012
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Abstract of thesis presented to the Senate of Universiti Putra Malaysia in fulfilment of
the requirements for the degree of Doctor of Philosophy
ROLE OF LENGTH SPECIFICITY, VELOCITY SPECIFICITY AND NEURAL
ADAPTATIONS IN STRENGTH TRAINING
By
AHMAD NAIM ISMAIL
March 2012
Chair: Tengku Fadilah Tengku Kamalden, PhD
Faculty: Faculty of Educational Studies
A very common finding among many training studies is that the increase in weight-
lifting strength is greater than the increase seen in isometric strength. Most are in view
that this is the result of training and testing specificity. However the exact underlying
mechanism that is responsible for the discrepancy has yet to be explained. The three
studies of this thesis examine the explanation behind the discrepancy between the
increases seen in weight-lifting strength compared to isometric strength after resistance
training.
The first study was to look into the role of learning. Thirty two students completed the
training. The subjects underwent four weeks of unilateral leg extension training, three
times per week,three sets of eight lifts. One leg was chosen arbitrarily for the training.
The contralateral leg, which was not trained, acted as a control. Subjects performed at a
steady pace. The result showed that the lesser experienced subjects showed a significant
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improvement in training weights lifted which illustrated that weight-lifting is very much
a skill based task.
The second study was to look into length specificity and velocity specificity. Eighteen
subjects completed the study. Subjects completed eight weeks of leg extension training,
three times per week,four sets of six to eight lifts. One leg was arbitrarily assigned to
perform the dynamic training. Isometric strength measured in the strength-testing chair.
Measurements of isometric strength at 15° intervals from 60° to 105° of knee flexion
using isokinetic dynamometer. Isokinetic strength testing was also measured at
velocities of 45° s-1
, 180° s-1
and 300° s-1
. A non-significant 6% increase of isometric
maximum voluntary contraction (MVC) at 90° was found and between 13% and 19%
.Increases of isometric torque were found at all angles measured. The training resulted
in increases in the isokinetic torque at all velocities for the trained leg. The result has
shown no evidence to any length or velocity specific adaptations.
The third study was to look into whether there is any increase in neural activity during
dynamic contractions in explaining the discrepancy between the increase in training
weights and MVC. Seven male subjects participated in this study. Subjects were trained
three times per week for four weeks, 80 - 85% of 1RM for three sets. One leg was
chosen randomly. Subjects performed dynamic leg extension on a leg extension
machine. The electromyogram (EMG) activity of vastus lateralis and biceps femoris
was recorded for the training and control leg during all testing. There were no
significant differences in terms of MVC force produced between the training chair and
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the strength testing chair. The EMG data showed there was no significant change in the
EMG activity of the vastus lateralis of the trained leg after training. There was a
reduction in EMG activity of the hamstring during the 1 RM post training but was not
significant. The results of the study have shown that there is no increase in neural
activity which would explain the difference between the increase in training weights
and MVC. Nor were there any significant changes in co-activation of the hamstring.
The discrepancy seen in the large increase in the weight lifting strength as compared to
isometric strength cannot be accounted for by the angle specificity and velocity
specificity factors. There is also no increase in neural activity which would explain the
difference between the increase in training weights and MVC. Nor were there any
significant changes in co-activation of the hamstring, consequently the discrepancy
remains unexplained.
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Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai
memenuhi keperluan untuk ijazah Doktor Falsafah.
PERANAN SPESIFISITI PANJANG, SPESIFISITI HALAJU DAN ADAPTASI
NEURAL DALAM LATIHAN KEKUATAN
Oleh
AHMAD NAIM ISMAIL
Mac 2012
Pengerusi: Tengku Fadilah Tengku Kamalden, PhD
Fakulti: Fakulti Pengajian Pendidikan
Kebanyakan dapatan daripada kajian mengenai latihan kekuatan mendapati bahawa
peningkatan kekuatan (selepas latihan kekuatan) untuk mengangkat bebanan adalah
melebihi kekuatan isometrik. Di antara alasan yang dikemukakan ialah kerana spesifisiti
latihan dan ujian. Tetapi, dari segi mekanisme yang sebenarnya terlibat masih belum
diketahui dengan jelas. Tiga kajian dalam tesis ini meneliti penjelasan di sebalik
percanggahan di antara peningkatan yang dilihat dalam kekuatan mengangkat bebanan
berbanding kekuatan isometrik selepas latihan kekuatan.
Kajian pertama adalah untuk mengkaji peranan pembelajaran. Seramai 32 subjek
menamatkan latihan setelah menjalani 4 minggu latihan ekstensi kaki unilateral, tiga
kali seminggu, tiga set lapan ulangan. Sebelah kaki telah dipilih secara rawak untuk
latihan. Kaki kontralateral, yang tidak terlatih, bertindak sebagai kawalan. Hasil kajian
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menunjukkan bahawa subjek yang kurang berpengalaman mempamerkan peningkatan
yang signifikan dalam mengangkat bebanan. Ini menunjukkan bahawa latihan kekuatan
(angkat bebanan) adalah satu kemahiran yang tersendiri.
Kajian kedua adalah untuk melihat spesifisiti sudut-panjang dan spesifisiti halaju.
Seramai 18 subjek terlibat dalam kajian ini. Subjek menyelesaikan lapan minggu latihan
ekstensi kaki, tiga kali seminggu, empat set 6-8 ulangan. Satu kaki secara rawak
ditugaskan untuk melaksanakan latihan. Kekuatan isometrik diukur di kerusi ujian
kekuatan isometrik. Pengukuran kekuatan isometrik pada 15° 60° hingga 105° fleksi
lutut juga diukur menggunakan dinamometer isokinetik. Ujian kekuatan isokinetik juga
diukur pada halaju 45° s-1
, 180° s-1
dan 300° s-1
. Satu peningkatan kekuatan isometrik
didapati sebanyak 6% tetapi tidak signifikan pada 90° dan peningkatan di antara 13%
dan 19% didapati pada semua sudut yang diukur menggunakan dinamometer isokinetik.
Latihan menyebabkan peningkatan tork isokinetik pada semua halaju untuk kaki
terlatih. Hasil kajian menunjukkan tiada bukti adaptasi spesifisiti sudut-panjang atau
spesifisiti halaju berlaku.
Kajian terakhir meninjau sama ada terdapat sebarang peningkatan dalam aktiviti neural
semasa kontraksi dinamik dalam menjelaskan percanggahan di antara peningkatan
dalam berat latihan dan peningkatan kekuatan isometrik. Tujuh subjek lelaki mengambil
bahagian dalam kajian ini. Subjek telah dilatih tiga kali seminggu selama empat
minggu, 80 - 85% daripada 1RM sebanyak tiga set. Subjek melakukan ekstensi kaki
dinamik menggunakan mesin extensi kaki. Aktiviti electromyogram (EMG) vastus
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lateralis dan biseps femoris dicatatkan bagi kaki latihan dan kawalan dalam semua
ujian. Terdapat tiada perbezaan yang signifikan dihasilkan antara kerusi latihan dan
kerusi ujian kekuatan. Data EMG menunjukkan tiada perubahan signifikan dalam
aktiviti EMG bagi vastus lateralis selepas latihan. Terdapat pengurangan dalam aktiviti
EMG biseps femoris selepas latihan tetapi tidak signifikan. Kajian terakhir tesis ini
menunjukkan dengan jelas bahawa tiada sebarang peningkatan aktiviti neural yang
boleh menjelaskan perbezaan di antara peningkatan mengangkat bebanan dengan
peningkatan kekuatan isometrik selepas sesuatu latihan dijalankan. Didapati juga
bahawa tidak terdapat perubahan yang signifikan bagi koaktivasi otot hamstring.
Dengan itu penjelasan tentang mengapa terdapat perbezaan yang ketara itu masih tidak
dapat dijelaskan oleh kajian dalam tesis ini.
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ACKNOWLEDGEMENTS
I would like to thank all of my friends and my family for the support and
encouragement over these years. I am also indebted to all the volunteers that were
involved in this work.
A special acknowledgement to my supervisor for the motivation and guidance.
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I certify that a Thesis Examination Committee has met on March 30, 2012 to conduct
the final examination of Ahmad Naim Ismail on his thesis entitled “ROLE OF
LENGTH SPECIFICITY, VELOCITY SPECIFICITY AND NEURAL
ADAPTATIONS IN STRENGTH TRAINING” in accordance with the Universities
and University Colleges Act 1971 and the Constitution of the Universiti Putra Malaysia
[P.U.(A) 106] 15 March 1998. The Committee recommends that the student can be
awarded the degree of Doctor of Philosophy.
Members of the Thesis Examination Committee were as follows:
Roselan Baki, PhD
Faculty of Educational Studies
Universiti Putra Malaysia
(Chairman)
Kok Lian Yee, PhD
Faculty of Educational Studies
Universiti Putra Malaysia
(Internal Examiner)
Saidon Amri, PhD
Faculty of Educational Studies
Universiti Putra Malaysia
(Internal Examiner)
Alun Williams, PhD
Department of Exercise & Sport Science
Manchester Metropolitan University
United Kingdom
(External Examiner)
________________________
SEOW HENG FONG, PhD
Professor and Deputy Dean
School of Graduate Studies
Universiti Putra Malaysia
Date:
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This thesis was submitted to the Senate of Universiti Putra Malaysia and has been
accepted as fulfillment of the requirement for the degree of Doctor of Philosophy. The
members of the Supervisory Committee were as follows:
Tengku Fadilah Tengku Kamalden, PhD
Senior Lecturer
Faculty of Educational Studies
Universiti Putra Malaysia
(Chairman)
Aminuddin Yusof, PhD
Associate Professor
Faculty of Educational studies
Universiti Putra Malaysia
(Member)
Mohd Roslan Sulaiman, PhD
Professor
Faculty of Medicine and Health Sciences
University Putra Malaysia
(Member)
__________________________________________
BUJANG BIN KIM HUAT, PhD
Professor and Dean
School of Graduate Studies
Universiti Putra Malaysia
Date:
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DECLARATION
I declare that the thesis is my original work except for quotations and citations which
have been duly acknowledged. I also declare that it has not been previously, and is not
concurrently, submitted for any other degree at Universiti Putra Malaysia or at any other
institution.
____________________________
AHMAD NAIM ISMAIL
Date:
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TABLE OF CONTENTS
Page
ABSTRACT ii
ABSTRAK v
ACKNOWLEDGEMENTS viii
APPROVAL ix
DECLARATION xi
LIST OF TABLES xiv
LIST OF FIGURES xvii
LIST OF ABBREVIATIONS xxi
CHAPTER
1 INTRODUCTION AND LITERATURE
REVIEW
Introduction 1
Factors Relating to Muscle Strength 5
Specificity of Strength Training 10
Neural Adaptations 13
Direction of This Work 25
2 GENERAL METHODS
Strength Measurements 26
Electrical Stimulation and Voluntary Activation 33
EMG Measurements 36
3 ROLE OF LEARNING IN CHANGES SEEN
IN WEIGHT TRAINING: A COMPARISON
OF BOYS WITH DIFFERING LEVELS OF
SPORTING EXPERIENCE
Introduction 39
Methods 41
Results 46
Discussion 50
4 ROLE OF LENGTH SPECIFICITY AND
VELOCITY SPECIFICITY IN STRENGTH
TRAINING
Introduction 55
Methods 58
Results 61
Discussion 75
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5 RELIABILITY OF USING M-WAVE IN
NORMALIZING THE EMG SIGNALS
Introduction 81
Methods 83
Results 91
Discussion 100
6 ROLE OF NEURAL ADAPTATIONS IN
SHORT TERM DYNAMIC WEIGHT
TRAINING
Introduction 103
Methods 105
Results 109
Discussion 120
7
CONCLUSION 124
REFERENCES 130
APPENDICES 150
BIODATA OF STUDENT 151
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LIST OF TABLES
Table Page
2.1 COV of 1RM 27
2.2 COV of MVC 28
2.3 COV at Various Angle of Knee Flexion 31
2.4 COV of Torque-velocity Relationship at
Various Speed
32
2.5 COV % of Activation 35
3.1 Age, Height, Weight and Maturity 46
3.2a Pre and Post 1RM for Sports School 47
3.2b Pre and Post 1RM for Non Sports School 47
3.3a Pre and Post MVC for Sports School (SS) 48
3.3b Pre and Post MVC for Non Sports School
(NSS)
49
3.4 Pre and Post Training Differences of 1RM 49
4.1 Physical Characteristics of the Subjects 58
4.2 1RM (Newtons) Pre and Post Training for the
Trained Legs of the Male and Female after 8
Weeks of Training
61
4.3 1RM (Newtons) Pre and Post Training for the
Untrained Legs after 8 Weeks of Training
62
4.4 1RM (Newtons) Pre and Post Training for
Trained (T) and Untrained Leg (UT) for Male
and Female and Control Subjects After 8
Weeks of Training
62
4.5 Isometric MVC for the Pre and Post Training of
the Trained Leg
65
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4.6 Isometric MVC for the Pre and Post Training of
the Untrained Leg
66
4.7 Isometric MVC for the Pre and Post Training of
the Trained (T) and Untrained (UT) Leg of
Male and Female and Control Group
66
4.8 Changes Seen in the Angle-torque Relationship
in the Trained Leg after 8 Weeks of Training
68
4.9 Changes Seen in the Angle-torque Relationship
in the Untrained Leg after 8 Weeks of Training
69
4.10 Angle-torque Relationship for the Pre and Post
Training of the Trained and Untrained Leg of
Male and Female Subjects
70
4.11 Isokinetic Torque at 3 Angular Velocities of the
Trained Leg after 8 Weeks of Training
73
4.12 Isokinetic Torque at 3 Angular Velocities of the
Untrained Leg after 8 Weeks of Training
74
4.13 Isokinetic Torque at 3 Angular Velocities for
the Pre and Post Training of the Trained and
Untrained Leg of Male and Female Subjects
74
5.1 Height, Weight and the MVC of the Subjects 84
5.2 Variance of sEMG and Normalising the EMG
Data by using sEMG Divided by the Amplitude
of the M-Wave
96
5.3 Normalising the EMG Data by using sEMG
Divided by the sMWave
96
5.4 Variance of iEMG and iMWave and
Normalising the EMG Data by using iEMG
Divided by the iMWave
97
5.5 % COV of the EMG Parameters of the 4
Subjects (Day to Day Variations) on 3 different
Days
97
6.1 Physical Characteristics of the Subjects 106
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6.2 i. 1RM (Newtons) and ii. MVC (Newtons) Pre
and Post Training for Trained Legs. The
Isometric MVC was tested on the Strength
Testing Chair Condition
110
6.3 i. 1RM (Newtons) and ii. MVC (Newtons) Pre
and Post Training for Untrained Legs. The
Isometric MVC was Tested on the Strength
Testing Chair Condition
110
6.4 Summary of the 1RM (Newtons) and MVC
(Newtons) Pre and Post Training for Trained
(T) and Untrained (UT) Legs
111
6.5 MVC Forces Produced in the Cybex Training
Chair (Measured at 105° Knee Flexion) and in
the Strength-testing Chair (Measured at 90°
Knee Flexion). Units in Newton-meter (Nm)
113
6.6 Rectified, Smoothed EMG (rsEMG) for 1RM
and MVC for the Trained Leg
115
6.7 Rectified, Smoothed EMG (rsEMG) for 1RM
and MVC for the Untrained Leg
115
6.8 Amplitude of Rectified Smoothed EMG
(rsEMG) of 1RM and MVC of the Hamstring
(Trained Leg)
117
6.9 Amplitude of Rectified Smoothed EMG
(rsEMG) of 1RM and MVC of the Hamstring
(Untrained Leg)
117
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LIST OF FIGURES
Figure Page
2.1 Cybex-VR2 Leg Extension Machine 27
2.2 Isometric Strength Testing Chair 28
2.3 Ankle Strap and Strain Gauge 29
2.4 Example of the Calibration 29
2.5 Cybex Norm Isokinetic Dynamometer 30
2.6 (i) Digitimer Stimulator Model DS7, UK 33
2.6 (ii) CED-1401, Cambridge Electronic Design Ltd.,
UK
33
2.7 The Twitch Interpolation Technique To
Estimate Level of Muscle Activation
34
2.8 Bipolar Surface Electrodes 36
2.9 EMG Activity of the Vastus Lateralis, Showing
Raw, Rectified and Smooth EMG
37
2.10 Schematic Representation of the Experimental
Set Up For Detecting EMG Signals, Force
Management and Stimulating the Muscle
37
3.1 Universal Powercircuit Leg Extension Machine 43
3.2 Percentage Increase of 1RM after Training of
the Trained Leg and Untrained Leg of SS and
NSS
48
4.1 Percentage Change in the Weight Lifted (1RM)
in Trained, Untrained Leg and Control Group
after 8 Weeks of Training
63
4.2 Percentage Change in the Weight Lifted (1RM)
in Trained Leg versus Weeks of Training
63
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4.3 Voluntary Activation of the Trained (Shaded
Bar) and Untrained (Open Bar) Leg Pre and
Post Training
64
4.4 Percentage Change in Isometric MVC in the
Trained, Untrained Leg and the Control Group
after 8 weeks of Training
67
4.5 Changes in the Angle-torque Relationship for
the Trained Leg
71
4.6 Changes in the Angle-torque Relationship for
the Untrained Leg
71
4.7 Percentage Change in the Angle-torque
Relationship in the Trained (Clean Bar),
Untrained (Dark Bar) and Control (Grey Bar)
after 8 Weeks of Training
72
4.8 Percentage Change in Isokinetic Torque at 3
Angular Velocities in the Trained (Clean Bar),
Untrained (Dark Bar) and Control (Grey Bar)
Leg after 8 Weeks of Training
75
5.1 Femoral Nerve Which Runs Lateral to the
Femoral Artery
85
5.2 The Cathode Probe 86
5.3 The femoral nerve (c) lies parallel to the
femoral artery (b). (a) is the femoral crease
which is just below the inguinal ligament
86
5.4 M-Waves Recorded from the Three Muscles, V.
Lateralis, R. Femoris and V. Medialis
87
5.5 Smoothed, Rectified Raw EMG and the Force
Elicited
89
5.6 Integrated, Rectified and Raw EMG 89
5.7 The Raw, Rectified and Amplitude of
Smoothed M-Wave of Vastus Lateralis
90
5.8 The Raw, Rectified and Integrated M-Wave of
Vastus Lateralis
90
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5.9 (a) Low Amperage at 100 mA 92
5.9 (b) Medium Amperage at 200 mA 92
5.9 (c) High Amperage at 300 mA 92
5.9 (d) A Typical M-Wave of the Vastus Lateralis at
100 mA
92
5.10 The Timing of the Evoked M-Waves after
Being Stimulated by a Single Pulse. X, Y and Z
Represents the Timing of the Vastus Medialis,
Rectus Femoris and Vastus Lateralis
Respectively
93
5.11 M-Waves Signal of the Vastus Lateralis, Rectus
Femoris and Vastus Medialis Recorded at
Various Current. The Force Elicited by the
Stimulation is shown in Newtons (N) on the
Secondary Axis Above It
94
5.12 (a,b,c) Amplitude of the M-Waves of the Three
Muscle at Different Currents taken 3 Times
During the Day
95
5.12 (d,e,f) Amplitude of the M-Waves of the Three
Muscle at Different Currents taken on 3
Subsequent Days
95
5.13 Mean % COV of the EMG Parameters of the 4
Subjects (Day to Day Variations) on Three
Different Days
98
5.14 The Branching of the Nerves in Relation to the
Placing of the Electrodes. X,Y,Z is the
Placement of the Electrodes for Vastus
Lateralis, Rectus Femoris and Vastus Medialis
Respectively and a,b,c is the Place Where the
Femoral Nerves Enters the Vastus Lateralis,
Rectus Femoris and Vastus Medialis
Respectively
99
6.1 EMG of the Biceps Femoris vs Force during a
Flexion
108
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6.2 The Increase in Weight Lifted (1RM) for 4
Weeks of Training
109
6.3 Percentage Change in Weights Lifted (1RM)
and in Isometric MVC in Trained and
Untrained Legs after 4 Weeks of Training
111
6.4 Percentage Change in Weight Lifted (1RM) and
Isometric MVC of the Trained Leg
112
6.5 Percentage Change in Isometric MVC of the
Testing Chair at 105o of Knee Flexion and at
90o Knee Flexion. No significant difference
(p=0.51)
113
6.6 Voluntary Activation of the Trained and
Untrained Before (Shaded) and After (Clear)
Training
114
6.7 EMG Activity of the Vastus Lateralis during
1RM Leg Extension (Cybex VR-2) and MVC
(Strength Testing Chair) of the Trained Leg and
Untrained Leg Pre (Shaded) and Post (Clear)
Training
116
6.8 EMG Activity of the Hamstring during a 1RM
Leg Extension (Cyber VR-2) and MVC
(Strength Testing Chair) of the Trained Leg and
Untrained Leg Pre (Shaded) and Post (Clear)
Training
118
6.9 Relationship of Rectified, Smoothed EMG of
Biceps Femoris and Antagonist Force
119
6.10 Relationship of Rectified, Smoothed EMG of
Vastus Lateralis, Biceps Femoris and
Quadriceps Force
119
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LIST OF ABBREVIATIONS
CSA - cross-sectional area
CNS - central nervous system
EMG - electromyography
iEMG - integrated electromyography
sEMG - smoothed electromyography
rsEMG - rectified smoothed electromyography
COV - coefficient of variation
1 RM - one repetition maximum
SD - standard deviation
MVC - maximal voluntary contraction
MAP - muscle action potential