study of how the muscles around the wrist and...

STUDY OF HOW THE MUSCLES AROUND THE WRIST AND

ELBOW AFFECT PERFORMANCE USING ELECTROMYOGRAPHY ON THAI AMATEUR AND

PROFESSIONAL GOLFERS

NIRUT SANCHAI

A THESIS SUBMITTED IN PARTIAL FULLFILMENT OF THE REQUIREMENTS FOR

THE DEGREE OF MASTER OF SCIENCE (SPORTS SCIENCE) FACULTY OF GRADUATE STUDIES

MAHIDOL UNIVERSITY 2010

COPYRIGHT OF MAHIDOL UNIVERSITY

Copyright by Mahidol University

iii

ACKNOWLEDGEMENTS

The successful of this thesis would not have been accomplished without

the support, patience, guidance and kindness of the following people:

First, I would like to express my deepest gratitude to my advisor, Assistant

Professor Dr.Rungchai Chuanchaiyakul for his continuous support in this research. He

always provides valuable advice, guidance and valuable encouragement. Without his

encouragement and constant guidance, I could not have finished this thesis.

My sincere appreciation is also expressed to Associate Professor Dr.

Wattana Jalayondaycha and Dr.Metta Pinthong for their helpfulness, kindness and

suggestion. Specials thank is given to Assoc. Prof. Vijit Kanungsukkasem for

participating in the supervisory committee.

My appreciation is also expressed to all volunteers for their helpful

assistance and sincere cooperation throughout the study. I would like to express my

appreciation to my friends at SS for sharing valuable experiences.

Finally, I am deeply indebted to my family: my parents, my aunt, my uncle

and my special friend, Anne for their unlimited love, for educating me, for

unconditional support and encouragement to pursue my interests, for listening to my

complaints, for patience, for understanding me.

Nirut Sanchai


Fac. of Grad. Studies, Mahidol Univ. Thesis / iv STUDY OF HOW THE MUSCLES AROUND THE WRIST AND ELBOW AFFECTPERFORMANCE USING ELECTROMYOGRAPHY ON THAI AMATEUR AND PROFESSIONAL GOLFERS NIRUT SANCHAI 4937580 SPSS/M M.Sc.(SPORTS SCIENCE) THESIS ADVISORY COMMITTEE : RUNGCHAI CHUANCHAIYAKUL,Ph.D. WATTANA CHALAYONDACHA,Ph.D., METTA PINTHONG, Ph.D.

ABSTRACT

This study was aimed at investigating the strength and sequences of muscles around the wrists and elbows of Thai professional(Pro, n = 10) and amateur(Am, n = 10) golfers. They were all right-handed. Pro golfers had a 0 handicap with a mean age = 29.10 ±6.59 yrs, a mean body weight = 70.6 ±7.50 kg and a mean height = 175 ±7.78 cm; whereas Am golfers had a handicap between 19-24, a mean age = 33.3 ±4.62 yrs, a mean body weight = 72.2 ±16.51 kg, a mean height = 167 ±6.67 cm. The four muscle groups of interest included the right(R) and left(L) sides of the biceps brachii(BB), the triceps brachii(TB), the wrist extensor group(WE), and the wrist flexor group(WF). Peak torques of extension/flexion around the elbow and the wrist, as well as % maximum voluntary contraction (%MVC) during a golf swing were determined. The golf swing was subdivided into four phases; address, back swing, down swing and follow through. Analysis was performed using a paired t-test and ANOVA at p <0.05. Mean torques in Pro golfers were, mostly, similar to those in Am gofers, except for left elbow extension (LEE) (p<0.05). EMG data revealed that Pros had a significantly higher RWE (right wrist extensor) (p<0.05), and RWF (right wrist flexor) (p<0.05) during back and down swings, respectively. Muscle activity for RBB, LBB, RTB, LTB, LWE, and LWF were all similar. Comparisons of %MVC obtained from isokinetic functions indicated that Pros exhibited maximal activation of RTB whereas LTB was second. It was found that there were co-contractions of agonists and antagonists of either wrist or elbow muscles in which these co-contractions were greater in the Pro group. In addition, Pros exerted greater LTB, WF and WE functions. These findings might be reflected by the better swing performance and skill in the Pro group. This requires further study in order to enhance performance in golfers. KEY WORDS : GOLF / ELETROMYOGRAM / ISOKINETIC 80 pages


Fac. of Grad. Studies, Mahidol Univ. Thesis / v การศกษาการทางาน และ คลนไฟฟา ของกลามเนอ รอบขอมอและขอศอก ในนกกอลฟ อาชพ และ สมครเลนชายไทย (STUDY OF HOW THE MUSCLES AROUND THE WRIST AND ELBOW AFFECT PERFORMANCE USING ELECTROMYOGRAPHY ON THAI AMATEUR AND PROFESSIONAL GOLFERS) นรตต แสนไชย 4937580 SPSS/M วท.ม.(วทยาศาสตรการกฬา) คณะกรรมการทปรกษาวทยานพนธ: รงชย ชวนไชยะกล, Ph.D, วรรธนะ ชลายนเดชะ, Ph.D, เมตตา ปนทอง, Ph.D.

บทคดยอ การศกษาครงนมจดประสงคเพอศกษาความแขงแรง และลาดบการทางานของกลามเนอรอบขอมอ และขอศอกในนกกอลฟชายไทย ถนดขวา แบงเปนนกกอลฟ 2 กลมคอ นกกอลฟอาชพ (Pro, แฮนดแคป 0) 10 คน (อาย 29.10 ±6.59 ป, นาหนก 70.6 ±7.50 กโลกรม, สง 175 ±7.78 เซนตเมตร และกลมนกกอลฟสมครเลน (Am, แฮนดแคป 19-24) 10 คน (อาย 33.3 ±4.62 ป, นาหนก 72.2 ±16.51 กโลกรม, สง 167 ±6.67 เซนตเมตร) ศกษากลามเนอ Biceps brachii (BB), Triceps brachii (TB), wrist extensor group (WE), wrist flexor group (WF) ของแขนทงขาง ขวา (R) และซาย (L) ตวแปรททาการศกษาคอ คาแรงบดสงสดของการงอ-เหยยดขอศอกและการงอ-กระดกขอมอ รอยละของการทางานสงสดของกลามเนอ (%MVC) ในขณะตกอลฟ แบงชวงการเคลอนไหวของการตกอลฟออกเปน 4 ชวง คอ address, back swing, down swing และ follow through โดยขอมลทไดถกนามาวเคราะหทางสถตโดยใช pair t-test และ ANOVA ทระดบความเชอมน p <0.05 คาเฉลยแรงบดสงสดในการเหยยดศอกซาย (left elbow extension, LEE) แตกตางกนอยางมนยสาคญ(p<0.05) และจากการศกษาคา %MVC พบวารปแบบการทางานของกลามเนอ RWE และ RWF ตางกนอยางมนยสาคญในชวง back swing (p<0.05) และ down swing (p<0.05) ตามลาดบ สวนกลามเนอ RBB, LBB, RTB, LTB, LWE, LWF มลกษณะการทางานทใกลเคยงกน กลามเนอทมการทางานมากทสดคอ RTB และ LTB ตามลาดบ นอกจากนนในขณะตกอลฟยงพบวาเกดรปแบบการทางานแบบ co-contraction ของกลามเนอขอศอก และขอมอ ซงพบชดเจนมากในกลมนกกอลฟอาชพ จากการศกษาในครงนสามารถนาไปใชในการพฒนา และปรบปรงโปรแกรมการฝกซอมของนกกอลฟไดในอนาคต 80 หนา


vi

CONTENTS

Page ACKNOWLEDGEMENTS iii

ABSTRACT(ENGLISH) iv

ABSTRACT(THAI) v

LIST OF TABLES viii

LIST OF FIGURES ix

LIST OF ABBREVIATIONS xi

CHAPTER I INTRODUCTION 1

Objectives 2

Hypothesis 2

Selected Parameters 3

Benefits of the Study 3

Scope of the Study 3

CHAPTER II LITERATURE REVIEW 4

Skeletal Muscle Function 4

Electromyography 8

Isokinetic dynamometry 15

Using EMG with Isokinetic 17

Introduction of golf 17

Electromyography research in golf 24

CHAPTER III METHODS 26

Study Designed 26

Materials and methods 26

Variables 28

Instrumentation 28

Data Collection 29


vii

CONTENTS (cont.)

Page CHAPTER IV RESULTS 32

General characteristics 32

Performance and contributions of muscles 34

around wrist and elbow during golf swing

- Biceps Brachii Muscle 35

- Triceps Brachii Muscle 40

- Wrist extensor groups 46

- Wrist flexor group 53

CHAPTER V DISCUSSION 59

Subject recruitment 59

Muscle Function Assessment in Golfers 60

Muscle performance during golf swing 61

Muscle activation during golf swing 62

Stretch-shortening cycle mechanisms 63

Muscle Co-contraction 65

Reciprocal Inhibition 65

Limitations of the current study 66

CHAPTER VI CONCLUSION 67

REFERENCES 68

APPENDICES 76

BIOGRAPHY 80


viii

LIST OF TABLES

Table Page

2.1 The name representative golf score count. 21

2.2 Summary of most active muscles in whole body 25

during the golf swing phase

4.1 General characteristics of subjects and maximum 33

isometric handgrip strength.

5.1. Summary on increasing of activities and contributions 63

of muscles around elbows and wrists.


ix

LIST OF FIGURES

Figure Page

2.1 Schematic of motor 3 units with different thresholds. 5

2.2 Motor units recruitment in the order of their sizes 7

depending on force they must produce.

2.3 Needle electrodes and surface electrodes 11

2.4 The difference griping technique in golf 23

2.5 The golf swing phase 23

3.1 Locations for skin electrodes for wrist and elbow 30

to investigate electrical activities of flexors and extensors

4.1 Means ± SEM of resting isokinetic peak torques (N.m) 35

4.2 Representatives raw EMG of biceps brachii 37

4.3 Representatives EMG of Root mean square of Briceps branchii 38

4.4 Means %MVC electromyographic data of Biceps brachii 41

4.5 Representatives raw EMG of Triceps brachii 42

4.6 Representatives EMG of Root mean square of Triceps branchii 44

4.7 Means %MVC electromyographic data of Triceps Brachii 47

4.8 Representatives raw EMG of wrist extensor 48

4.9 Representatives raw EMG of wrist extensor 50

4.10 Means %MVC electromyographic data of wrist extensor 52

4.11 Representatives raw EMG of wrist flexor muscles 54

4.12 Representatives EMG of Root mean square of wrist flexor 56


x

LIST OF FIGURES (cont.)

Figure Page

4.13 Means %MVC electromyographic data of wrist flexor 58

5.1 Normalized electromyographic amplitudes versus 61

isotonic load and isokinetic contraction

5.2 Simple stretched-shortening cycle in single-handed 64

and double-handed sports


Fac. of Grad. Studies, Mahidol Univ. M.Sc.(Sports Science) / 1

CHAPTER I

INTRODUCTION

Golf is increasingly popular in Thailand. It is estimated that many Thai

people of all ages participate in this sport. There are more than 800 professional

golfers and more than 190 courses available in the country (TPGA, 2007). Unlike any

other sports, golf does not require high levels of aerobic capacity but it does involve

extremely with high levels of skill (Aaron and David, 2000). This particular sport,

therefore, relies on tactic rather than physical performance. While the latter consists of

strength, endurance, flexibility, coordination, and power, the first depends on specific

athletes’s skill and talent (Peltola, 1992; Thomson, 1992). Particular areas that may

need to develop golf performance, including anthropometry (Fornetti et al., 1999)

physiology (Skubig and IIodgkins, 1966; Aaron and David, 2000), biomechanics

(Hume et al.,2005), psychology (Richard Mullen ,2005), nutrition (Ralf et al.,2007)

and sport medicine (Dennis et al.,1982) have been previously investigated. For

example, physiology of golf had been explored and identified in terms of

cardiopulmonary systems, thermoregulation systems (Skubig and IIodgkins, 1966;

Hausman et al., 1972). Skill in golfers was investigated, however, it was, more or less,

related to equipments (Egret et al.,2003).

A few studies have been concentrated in neuromuscular function of

golfers, in particular sequential electrical activation of agonist-antagonist muscles

which bring about muscle strength, power and coordination (McHardy and

Pollard,2005). It is found that there are significant correlations between muscle

contraction and electromyography (EMG) signals among different muscles following

training (Lebar et al., 2005). It is known that muscle function, as well as coordination,

of muscles around shoulder, elbow, wrist and hand is the key determinant in golf

swing (Koon et al., 2006). From previous studies, performance during golf swing is

still relied mostly on activity of shoulder muscles (Jobe et al., 1986-1989; Pink et al.,

1990; Glousman, 1993). In fact, muscle around hands, wrists and elbows play critical

role during swinging phase, which determine direction, distance of the ball (Nagao and


Nirut Sanchai Introduction / 2

Sawada, 1977). However, very few investigations have been explored on muscle

function around wrist and elbow(Abernethy et al., 1990; Glazebrook et al, 1994 ).

In addition, there are very few researches about performance of Thai

golfers.As to our knowledge, no investigation on EMG in muscle firing pattern around

wrist and elbow in Thai golfers have ever been explored before. Therefore, we rely on

limited information to enhance golfer players in Thailand. Apart from shoulder

muscles function, it is believed that advantages and disadvantages found in

professional golfers might be derived form different time-series and efficiency

changes of muscle around wrist and elbow. The present study will be initially

concentrated, on laboratory basis, on isokinetic strength in parallel to EMG of muscle

around wrist and elbow. Secondly, sequential and magnitudes of activations of

antagonists-agonists muscles around wrist and elbow during golf swing in the driving

range will be investigated.

Objectives

1. To investigate muscle performance profiles, both sides,

of wrists and elbows in professional and amateur golfers

during swing phase.

2. To define muscle electrical activities of muscles around

wrists and elbows in professional and amateur golfers

during golf swing.

3. To compare muscle performance profiles and muscle

electrical activities of muscles around wrists and elbows

between professional and amateur golfers during swing

phase.

Hypothesis It is hypothesized that there might be some differences in muscle

function and sequential changes of EMG of muscles around the wrist and elbow in

professional and amateur golfers.



Selected Parameters 1. Age

2. Weight

3. Golf experience

4. Percentage of body fat

5. Handgrips force

6. Peak torque of isokinetic test

7. Blood pressure (Systolic and Diastolic) and Mean

Arterial Pressure (MAP)

8. Heart rate (HR)

Benefits of the Study This study may reveal the differential of muscle performance

and electrical activity between Thai professional and amateurs golfer .

In addition, the results of this study can be applied in other

medical science studies such as characteristic to create “golfer’s elbows” or adapted

in specific strength and conditioning program design , golf instructor ,golf equipment

,such as glove, joint support for injured golfer .

Scope of the Study This research was designed into two sections and tested in

healthy 20 male golfers. First, subjects were requested to participate to hitting in five

balls to the net, for measuring the electrical activity Second, subjects were tested with

isokinetic machine to measure peak torque. Both data were specific about muscle

around wrist and elbow joint only. There had been recorded and analyzed,

scientifically.


Nirut Sanchai Literature Review / 4

CHAPTER II

LITERATURE REVIEW

1. Skeletal Muscle Function 1.1. Muscle fiber and bioenergetics

The muscle fibers are connective tissues which can be activated and

resulted in contraction. Contractile protein contained in functional unit of muscle,

named as actin, moves against another contractile protein, myosin, which then pull

together to create contraction. Parts, or ends, of muscle belly converge to form tendons

which attach on bones. As a result of muscle contraction, force and torque are

produced. (Cram et al., 1997).Muscle contraction is stimulated by electrical impulses

controlled by the brain and transmitted via the nerves. From motor neurons, electrical

signals are conveyed, via motor nerves, to muscle fibers. With these neural pathways

from higher center toward motor fibers, it is, therefore, implied that skeletal muscle

voluntarily controlled for purposeful movement and locomotion( Kumar and Mital

1996). Cardiac and smooth muscles, on the other hands, are stimulated internally and

involuntarily by specialized cells known as pacemaker cells(Cram et al., 1997).All

skeletal muscle and many smooth muscle contractions are facilitated by the

neurotransmitters. Muscular activity accounts for much of the body's energy

consumption. All muscle cells produce adenosine triphosphate (ATP) molecules which

are used to power the movement of the myosin heads. Muscles conserve energy in the

form of creatine phosphate which is generated from ATP and can regenerate ATP

when needed using a specialize enzyme named as creatine kinase. Muscles also keep

storage form of glucose in the form of glycogen which can be rapidly converted to

glucose when energy is required for sustained, powerful contractions. Skeletal muscles

produce energy, ATP, from glucose via 2 main different processes: anaerobic and

aerobic glycolysis in which different amounts of ATP are liberated. Muscle cells also

contain globules of fat, which are used for energy during aerobic exercise.



Accordingly, different muscle fiber types contract at different rates

depending on activities of Myosin ATPase (Maxwell et al. 1982 ). Muscle fibers are,

therefore, can be classified as Type I (slow twitch, red fiber), Type IIA (Fast oxidative

glycolysis) and Type IIB (Fast glycolysis, white fiber) (Remaud et al.,2005).

1.2. The motor unit

One motor nerve is branched into many small nerve fibers in which each

nerve fiber terminates on a different muscle fiber. A motor unit represents groups of

muscle fibers which are supplied by a motor nerve (Figure 2.1). Motor units can be

characterised by their different contractile, energetic and fatigue properties. A single

motor unit always consists entirely of either type I (slow twitch) or Type II (fast

twitch) fibers. Since a muscle belly is innervated with mixed nerve fibers. For

example, some motor units in one muscle belly are controlled by fast some is

innervated by slow fibers. This makes function of entire muscle belly heterogeneously.

The number of muscle fibers per motor unit varies greatly in the human body.

Figure 2.1 Schematic of motor 3 units with different thresholds. All muscle fibers

within the same motor unit response simultaneously when a motor nerve is stimulated.

( Thomas,1987 )



1.3 Motor unit recruitment pattern

Motor unit recruitment is main part of increasing muscular force when it is

needed. This recruitment does not occur in a random fashion but is controlled by

higher center. Motor units are recruited according to the “Size Principle”. This means

smaller motor units, which contain fewer muscle fibers and have a small motor neuron

and a low threshold for activation, will be recruited first. It is important that motor

units recruited for a given task must be appropriately fit with muscle fiber property

being activated. Many factors such as mechanics, sensory feedback, and central

control influence recruitment patterns. As more force is demanded by higher activity,

larger motor units are progressively recruited. This has great functional significance in

that man can generate greater force as needed. When requirements for force are low,

but control demands are high (for example, during fine work like writing, playing the

piano) the ability to recruit only a few muscle fibers gives the possibility of fine

control. As more force is needed the impact of each new motor unit on total force

production becomes greater. It is also important to know that the smaller motor units

are generally slow units, while the larger motor units are composed of fast twitch

fibers. The second method of force regulation is called “ RATE CODING ”. Within a

given motor unit there is a range of firing frequencies. Slow units operate at a lower

frequency range than faster units. Within that range, the force generated by a motor

unit increases with increasing firing frequency(Figure 2.2). If an action potential

reaches a muscle fiber before it has completely relaxed from a previous impulse, then

force summation will occur. By this method, firing frequency affects muscular force

generated by each motor unit ( Thomas,1987 )Central nervous system rotates which

motor units are firing within a given muscle group. In this way, the postural load of a

muscle is transferred from one motor unit to another in a smooth and continuous

fashion. In addition to its mechanical work, muscle tone provides the basis for

emotional tone. Anxiety or fear tends to take up the general slack of the

neuromuscular network. And finally, movements are superimposed upon the resting

tone of muscle. In our daily lives, as well as in athletic competition, it is important to

have the correct tone for the task at hand. Too much or too little, and the timing of

action becomes distorted.



When a muscle contraction initially occurs, the smallest muscle

fiber/motor units are recruited first, with the large muscle fiber/motor units being

called into play as the synaptic drive continues to increase. The firing rate of muscle

fiber is usually in the range of 8 to 50 Hz. As the exertional demands increase, the

firing rate moves from slower to higher frequencies. In addition, the motor unit

recruitment strategy can move from an asynchronous to a synchronous pattern. All of

these mechanisms result in higher s EMG reading.

Figure 2.2 Motor units recruitment in the order of their sizes depending on force they

must produce. With low (light) load resistance, Type I (slow twitch) motor units are

recruited predominantly. With highest load, Type IIb/x does the greatest force

production with the assistance of the Type IIa and Type I fibers. ( Heise ,1995 ).

1.4 Types of muscle Contributions to a Movement

Muscles are divided in three groups according to their contribution to

action or movements :

- Agonist muscles: The prime movers, they initiate the movement; they

generate most of the force.



- Antagonist muscles: Act in opposition to the movement; they provide a

stabilizing force during the movement.

- Synergist muscles: Assist the agonist muscles; they generate less

force but contribute to the control of the movement.

- Stabilizer muscles: Act to stabilize the origin of agonist muscle:

mainly not directly to generate force with agonist ,but help agonist to work more

efficiently.

2. Electromyography (EMG)

Electromyography, the studying of muscle electrical activity, is the

technique of detecting, recording and interpreting characteristics and changes in the

electrical potential of a muscle when it is caused to contract by a motor nerve impulse

(Kumar & Mital, 1996) The neural stimulation of the muscle fibre at the motor end-

plate results in a reduction of the electrical potential of the cell and a spread of the

action potential through the muscle fibre. The motor action potential (MAP), or

muscle fibre action potential, is the name given to the waveform resulting from this

depolarisation wave. This propagates in both directions along each muscle fibre from

the motor end-plate before being followed by a repolarisation wave. The action

potentials from these fibres at any workload, is therefore, possibly investigated.

Summation, over space and time, of the motor unit action potential trains from various

motor units is objectively assessed for muscle activity. It has been used to establish the

roles that muscles full fill both individually and in group actions. In addition, EMG

also provides information on the sequencing of the activity of various muscles in

sports motions. By studying the sequencing of muscle activation, the sports scientist

can focus on several factors that relate to skill, such as any overlap of agonist and

antagonist activity and the onset of antagonist activity at the end of a movement. It

also allows the sports scientist to study changes in muscular activity during skill

acquisition and as a result of training ( Heise ,1995 ).



2.1. EMG signal presentation

Electromyography may be simply analysed and presented as raw EMG,

which have both positive and negative values. The amplitude of this signal, and all

other EMG data, should always be related back to the signal generated at the

electrodes, not given after amplification. In the recent years, EMG signal processing is

often performed in sports biomechanics in an attempt to make comparisons between

studies using the signal correlation between EMG signal with mechanical actions of

the muscles or other biological signals ( Remaud et al.,2005 ). Although EMG

processing can provide additional information to that contained in the raw signal,

disadvantages of raw EMG appeared for several reasons: the artifacts involved with

EMG signal, the repeatability of EMGs is not likely taken place even from a

stereotyped activity such as treadmill running( Heise ,1995 ).Other common errors

include the preparation of electrodes and skin sites It is reported that even the activity

or inactivity of one motor unit near the pick-up site can noticeably change the signal

( Beck,2007 ). In addition, such experimental factors during movement study make it

difficult to compare raw EMG results with those of other studies(Gerdle et al., 1999).

However, normalisation has been developed to facilitate such comparisons. This

involves the expression of the amplitude of the EMG signal as a ratio to the amplitude

of a maximal contraction, usually obtained from EMG during maximum voluntary

contraction (MVC), from the same site (Kumar & Mital, 1996). No consensus at

present exists as to how to elicit an MVC and it is not always an appropriate maximum

(Burden, 2007).

Temporal processing and amplitude estimation relate to timing and

amplitude of signal content or the ‘amount of activity’. Such quantification is usually

preceded by full-wave rectification as the raw EMG signal would have a mean value

of about zero, because of its positive and negative deviations. Full-wave rectification

simply involves making negative to positive values. Average rectified EMG is the

typical value of the full-wave rectified EMG, and is easily computed from digital

signals by adding the individual EMG values for each sample and dividing by the

sample time. This is recommended by Surface Electromyography for the Non-Invasive

Assessment of Muscles (SENIAM) for amplitude estimation of the EMG in non-



dynamic contractions. The average rectified EMG is closely related to the integrated

EMG. As for other amplitude estimators of the EMG, the average rectified EMG is

affected by the number of active motor units; the firing rates of motor units; the

amount of signal cancellation by superposition; and the waveform of the motor unit

action potential(Cram et al., 1997). The last of these depends upon electrode position,

muscle fibre conduction velocity, the geometry of the detecting electrode surfaces and

the statistics. For a spectrum of discrete frequencies, the mean frequency is obtained

by dividing the sum of the products of the power at each frequency and the frequency,

by the sum of all of the powers. The median frequency is the frequency that divides

the spectrum into two parts of equal power–the areas under the power spectrum to the

two sides of the median frequency are equal. The median is less sensitive to noise than

is the mean. The spread of the power spectrum can be expressed by the statistical

bandwidth, which is calculated in the same way as a standard deviation. The EMG

power spectrum can be used, for example, to indicate the onset of muscle fatigue. This

is accompanied by a noticeable shift in the power spectrum towards lower frequencies

and a reduction in the median and mean frequencies.

2.2. Type of the EMG electrodes

Selection and placement of EMG electrodes are considerably importance

for sports physiology and biomechanics. Surface, non-invasive, electrode is selected

rather than indwelling invasive electrode, the latter is known as fine wire electrode

(Figure 2.3 A) and mainly used in clinical research. Surface electrode is safer, easier to

use and more acceptable to attached for superficial muscle EMG (Figure 2.3B).

According to SENIAM recommendations, bipolar electrodes of pre-gelled silver–

silver chloride material, which conforms to standard practice in sports biomechanics (

Cram , 2009 ) It is recommended a fixed distance of 20 mm between the centers of the

two pre-mounted electrodes.



Figure 2.3 needle electrodes Electrodes (A) and surface electrodes (B).

2.3 Artifacts or Noise Involvement (Gerdle et al., 1999).

Artifact is unwanted information contained within EMG signal. An EMG

signal is very tiny and sensitive to artifacts. Different artifacts involve with EMG

signals must be detected and prevented.

2.3.1 Line interference: This is the most common artifact. (Kumar &

Mital, 1996) It comes from the electric power line, 50/60Hz noise, and is transmitted

by electrical devices, which are placed near the EMG data acquisition box. Electronic

devices also generate frequencies that might interfere EMG signal.

2.3.2 Electrocardiogram artifacts: ECG signal, which is being

generated by the heart, can be picked up by some types of EMG device. ECG artifacts

can be avoided by placing the electrodes so that they are not aligned with the axis of

the heart activity, for example, avoid transthoracic placement. Placing the electrodes

on the same side of the body usually reduces or removes these artifacts. If these

precautions are not enough, a high-pass filter at 100Hz can be applied to the signal.

However, this filters extremely low frequencies from the EMG signal and may remove

important information (Kumar & Mital, 1996).



2.3.3 DC offset artifacts: This is caused by the difference in the

impedance between the skin and the electrodes. It adds an offset to the raw signal,

which is normally centered on 0. Proper skin preparation and firm placement of

electrodes on the skin generally prevent the problem. It is recommended that

conductive gel must be added(Kumar & Mital, 1996).

2.3.4 Muscle crosstalk: Muscle crosstalk is caused by EMG signals

coming from other muscles than the one being monitored. Crosstalk can be avoided by

choosing the appropriate inter-electrode distance (around 2 centimeters) and by

placing electrodes at the middle of the muscle belly (Kumar & Mital, 1996).

2.3.5 Movement artifacts: During subject movements, the electrodes

can move or the cables be pulled or be shaken, which may create artifacts in the EMG

signal. These artifacts can be avoided by using tape or an elastic band to fasten the

cables. Electrode movement can be avoided by choosing the right electrode type and

placing the electrodes firmly on the skin to avoid them peeling off. Inter-electrode

distance must also be chosen so that electrodes do not push against each other during

movement. A high-pass filter at 20Hz can be applied to the signal (hardware or

software) to remove the residual artifact. These artifacts can also be manually removed

from the statistics calculation during the review of the session(Kumar & Mital, 1996).

2.4 Skin and Electrode Impedance

Consistency in impedance is critical for the reliability of EMG

measurements. Modern pre-amplifier design (i.e. high input impedance) has reduced

the importance of measuring EMG with a low level of electrode – skin impedance.

While the absolute level of muscle impedance is not a critical factor, the stability in

impedance over time and the balance in impedance between electrode sites have a

considerable effect on the signal to noise ratio of the measured EMG signal (Freriks

and Hermens, 2000), both in terms of noise levels and spatial resolution. The balance

in impedance between electrode sites is important to minimize noise components. The

impedance at each site does not have to be perfectly balanced, however, they should

be relatively similar. The level of impedance balance is rather arbitrary, depending on

the properties of the differential pre-amplifier in use, among other factors. The



impedance determines the energy levels of the electrical signal measured at each

electrode site (i.e. the view of the muscle and environment that the electrode

measures). As the impedance becomes increasingly different between electrode sites,

so too does the signal strength entering the process of differential amplification.

Differential amplification only cancels common signal components. For example, if

the energy of power-line noise is different, some of the noise will remain in the signal

following the process of differential amplification (Gerdle et al., 1999). Similarly, the

D/C voltage potential will be different and part of it will not be cancelled. If the pre-

amplifier does not have sufficient D/C noise suppression in the residual D/C

component, once amplified, can lead to pre-amplifier instability, inaccuracy and

saturation. The general rule is the more balanced the electrode – skin impedance

between electrode sites, the lower the noise and as a result the higher the signal to

noise ratio. Given the 6 complexity of the EMG signal, it is difficult to predict or

measure to what extent imbalanced impedance alters the properties of the EMG signal.

Suffice it to say that by achieving a similar balance in impedance is the best way to

increase the reliability of EMG measurements. It is also important that the impedance

remains consistent over the duration of the measurement session. For the reasons

similar to those above, the signal to noise ratio will wander if the impedance drifts

during measurement, as will the spatial resolution of the recorded EMG signal. Recent

evidence demonstrates that the relative level of electrode skin impedance has a

significant effect on the energy of the measured EMG signal. That is, low impedance

(<10 kΩ) resulted in a high level of energy for EMG frequency components under 100

Hz as compared to high electrode – skin impedance ( >100 k Ω). In contrast, for EMG

signal frequency components between 100 and 150 Hz, low electrode – skin

impedance resulted in a lower signal energy level than the measurements with high

impedance (Hewson et al., 2002). Other findings support these results (Duff et al.,

2002), indicating the spatial resolution (i.e. the electrical view into the muscle) is

altered with changes in electrode – skin impedance. Therefore, it is very important that

the impedance remains consistent throughout the measurement session.



2.5 Skin Preparation

Impedance from the outermost layer of skin, including dead skin material

and oil secretions may be induced. This can be minimized with proper skin

preparation. In fact, the quality of contact is typically reduced by at least a factor of 10

with proper preparation ( Merletti and Migliorini, 1998 ). Proper skin preparation

makes reliability of good surface EMG signals ( Cram JR , 2009 ) The procedures for

skin preparation include: a) shave the skin; b). skin oil and dirt removal using alcohol;

c). some of the dead surface skin layer were removed using abrasive pad; d).wiped dry

the skin; e).applying electrolyte paste and f).applying the electrodes ( Hanney J,1986 )

2.6 EMG Normalization

The voltage potential of the EMG signal detected by the electrodes

strongly depends on several factors, varying between individuals and also over time

within an individual. Thus, the amplitude of the EMG itself is not useful in group

comparisons, or to follow events over a long period of time (Mathiassen, 1997). The

fact that the recorded EMG amplitude is never absolute is mainly due to the fact that

the impedance varies between the active muscle fibres and electrodes and is unknown

(Gerdle et al., 1999). Therefore, when comparing amplitude variables between

measurements, normalization of some kind is required, i.e. the EMG converted to a

scale that is common to all measurement occasions. Normalizing the signal amplitude

with respect to force or torque is a commonly used technique. Typically, the EMG is

related to a maximal contraction, or a submaximal contraction at a known level of

force. For other examples and types of signal normalization please see the papers by

Mathiassen et al. (1995, 1997) and Merletti et al. (1995).

2.7 Electrode Placement

The EMG signal provides a view of muscle electrical activity during

contraction. The electrical view is highly dependent on where the electrode is

overlying the muscle of interest. Since electrode placement determines the electrical

view of a muscle, then it is important in EMG measurements to be consistent in the

placement of the electrodes for a subject over consecutive recording sessions and

between different subjects (Corner CO et al.,2007) When determining electrode



placement, the use of the guidelines set forth in the international SENIAM initiative is

highly recommended. It is generally known that the sensor location is defined as the

position of the two bipolar sites overlying a muscle in relation to a line between two

anatomical landmarks. The goal of sensor placement is to achieve a location where a

good and stable surface EMG signal can be obtained. There are two general strategies

for placement of electrodes.

- Longitudinal placement: The bipolar electrode arrangement is placed

halfway from the distal motor end-plate (approximation – muscle mid-line) zone and

distal tendon. The goal is to avoid the sensor overlying the innervation zone or tendon

during the whole range of motion ( Wong Y,2007 )

- Transverse placement: The bipolar electrode on the muscle is placed

so that each sensor is away from the boundary of the muscle recording area of interest.

This can consist of the compartments of a large muscle and neighboring muscles

underlying the area of the electrode. Typically, this means that the line between the

centers of the electrode sensors is roughly parallel to the long axis of the muscle (

O’Dwyer N at al., 1981 ).

3. Isokinetic dynamometry ( Korkia and Li ,1996 )

The measurement of the net muscle torque at a joint using isokinetic

dynamometry is very useful in providing an insight into muscle function and in

obtaining muscle performance data for various modeling purposes ‘isokinetic’ is

derived from Greek words meaning ‘constant velocity’). Isokinetic dynamometry is

used to measure the net muscle torque during isolated joint movements. A variable

resistive torque is applied to the limb segment under consideration; the limb moves at

constant angular velocity once the preset velocity has been achieved, providing the

person being measured is able to maintain that velocity in the specified range of

movement. This allows the measurement of muscle torque as a function of joint angle

and angular velocity, which, at certain joints, may then be related to the length and

contraction velocity of a predominant prime mover, for example the quadriceps

femoris in knee extension. By adjusting the resistive torque, both muscle strength and

endurance can be evaluated. Isokinetic dynamometers are also used as training aids,



although they do not replicate the types and speeds of movement in sport. Passive

isokinetic dynamometers operate using either electromechanical or hydraulic

components. In these devices, resistance is developed only as a reaction to the applied

muscle torque, and they can, therefore, only be used for concentric movements.

Electromechanical dynamometers with active mechanisms allow for concentric and

eccentric movements with constant angular velocity; some systems can be used for

concentric and eccentric movements involving constant velocity, linearly changing

acceleration or deceleration, or a combination of these. Several problems affect the

accuracy and validity of measurements of muscle torque using isokinetic

dynamometers. Failure to compensate for gravitational force can result in significant

errors in the measurement of muscle torque and data derived from those

measurements. These errors can be avoided by the use of gravity compensation

methods, which are an integral part of the experimental protocol in most computerized

dynamometers. The development and maintenance of a preset angular velocity is

another potential problem. In the initial period of the movement, the dynamometer is

accelerated without resistance until the preset velocity is reached. The resistive

mechanism is then activated and slows the limb down to the preset velocity. The

duration of the acceleration period, and the magnitude of the resistive torque required

to decelerate the limb, depend on the preset angular velocity and the athlete being

evaluated. The dynamometer torque during this period is clearly not the same as the

muscle torque accelerating the system. If the muscle torque during this period is

required, it should be calculated from moment of inertia and angular acceleration data.

The latter should be obtained either from differentiation of the position–time data or

from accelerometers if these are available. Errors can also arise in muscle torque

measurements unless the axis of rotation of the dynamometer is aligned with the axis

of rotation of the joint, estimated using anatomical landmarks. For normal individuals

and small misalignments, the error is very small and can be neglected. Periodic

.Instantaneous joint power can be calculated from the torque (T) and angular velocity

(ω) when the preset angular velocity has been reached. Data processing in isokinetic

dynamometry the following parameters can normally be obtained from an isokinetic

dynamometer to assess muscle function .The maximum torque The isokinetic

maximum torque is used as an indicator of the muscle torque that can be applied in



dynamic conditions. It is usually evaluated from two to six maximal repetitions and is

taken as the maximum single torque measured during these repetitions. The maximum

torque depends on the angular position of the joint. Maximum power can also be

calculated. The reciprocal muscle group ratio The reciprocal muscle group ratio is an

indicator of muscle strength balance around a joint, which is affected by age,

biological sex and physical fitness. It is the ratio of the maximum torques recorded in

antagonist movements, usually flexion and extension, for example the quadriceps

femoris to hamstrings muscle group ratio. The maximum torque position is the joint

angular position at maximum torque and provides information about the mechanical

properties of the activated muscle group. It is affected by the angular velocity. As the

angular velocity increases, this position tends to occur later in the range of movement

and not in the mechanically optimal joint position. It is, therefore, crucial to specify

the maximum torque position as well as the maximum torque.

4. Using EMG with Isokinetic (Thought Technology Ltd., 2009).

EMG use in conjunction with isokinetic dynamometers has become very

popular in research as well as in clinical settings. Real-time physiology monitoring

(such as SEMG, heart rate and respiration) is an important asset to the data provided

by the isokinetic machine (position, torque and velocity). It provides the examiner

physiological data to validate the effectiveness of the training and helps the examinee

to modify their physiology (breathing patterns, muscle activation patterns, etc.) in real

time during the training. Regarding EMG, it allows the evaluation of the activity of

muscles or muscle groups during the movement (contraction intensity, timing,

sequence of firing and local muscle fatigue) and to correlate them to the phases of the

exercise (isometric, isokinetic, isotonic, concentric or eccentric). SEMG biofeedback

motivates the patient to play an active

5. Introduction of golf (The Royal and Ancient Golf Club of St Andrews (R&A),

2008)

5.1 Characteristics of golf

Golf is a precision club-and-ball sport in which competing

players(golfers), using many types of clubs, attempt to hit balls into each hole on a



golf course while employing the fewest number of strokes. Golf is one of the few ball

games that does not require a standardized playing area. Instead, the game is played on

golf "courses", each of which features a unique design, although courses typically

consist of either 9 or 18 holes. Golf is defined, in the rules of golf, as "playing a ball

with a club from the teeing ground into the hole by a stroke or successive strokes in

accordance with the Rules". Golf competition is generally played for the lowest

number of strokes by an individual, known simply as stroke play, or the lowest score

on the most individual holes during a complete round by an individual or team, known

as match play

Every round of golf is based on playing a number of holes in a given order.

A round typically consists of 18 holes that are played in the order determined by the

course layout. On a nine-hole course, a standard round consists of two successive

nine-hole rounds. Playing a hole on the golf course consists of hitting a ball from a tee

on the teeing area, called a drive on longer holes, a drive is a long-distance shot

intended to move the ball a great distance down the fairway, shorter holes can be

reached with clubs shorter than the driver. Once the ball comes to rest, the golfer

strikes it again with a lay-up, an approach, or a chip, until the ball reaches the green,

where he or she then putts the ball into the hole. The goal of sinking the ball in the

hole in as few strokes as possible may be impeded by hazards, such as areas of long

grass, bunkers, and water hazards. In most typical forms of game play, each player

plays his/her ball until it is holed.

5.2 Rules and regulations

The rules of golf are internationally standardized and are jointly governed

by The R&A, spun off in 2009 from The Royal and Ancient Golf Club of St Andrews

(founded 1754), and the United States Golf Association (USGA).

The underlying principle of the rules is fairness. As stated on the back

cover of the official rule book: Play the ball as it lies, play the course as you find it,

and if you cannot do either, do what is fair.

There are strict regulations regarding the amateur status of golfers.

Essentially, anybody who has ever received payment or compensation for giving

instruction or played golf for money is not considered an amateur and may not

participate in competitions limited solely to amateurs. However, amateur golfers may



receive expenses which comply with strict guidelines and they may accept non-cash

prizes within the limits established by the Rules of Amateur Status.

In addition to the officially printed rules, golfers also abide by a set of

guidelines called golf etiquette. Etiquette guidelines cover matters such as safety,

fairness, easiness and pace of play, and a player's obligation to contribute to the care of

the course. Though there are no penalties for breach of etiquette rules, players

generally follow the rules of golf etiquette in an effort to improve everyone's playing

experience

5.3 Golf equipment

Golf clubs are used to hit a golf ball. Each club is composed of a shaft with

a lance (grip) on the top end and a club head on the bottom. Woods, are used for long-

distance fairway shots; Hybrids are replacing long irons in many places because of

they are easier for the average golfer to use. irons, the most versatile class, are used for

a variety of shots, and putters, are used to roll the ball into the cup. Only 14 clubs are

allowed in a player's bag at one time during a stipulated round. Violation of this rule

can result in disqualification. Golf balls have "dimples" that decrease aerodynamic

drag by decreasing turbulence behind the ball in motion, which allows the ball to fly

farther. A tee is used for resting the ball on top of for an easier shot; allowed only for

the first stroke of each hole. Many golfers wear golf shoes with metal or plastic spikes

designed to increase traction thus allowing for longer and more accurate shots. A golf

bag is used to transport golf clubs. Golf bags have several pockets designed for

carrying equipment and supplies such as tees, balls, and gloves. Golf bags can be

carried, pulled on a two-wheel pull cart or harnessed to a motorized golf cart during

play. Golf bags have both a hand strap and shoulder strap for carrying, and sometimes

have retractable legs that allow the bag to stand upright when at rest.

5.4 Golf stroke mechanics

Golfers start with the non-dominant side of the body facing the target. At

address the body and club are positioned parallel to the target line. A more open stance

is used for shorter distance shots except putting and a more closed stance for long

distance shots. The feet are shoulder width apart for middle irons and putters, narrower

for short irons and wider for long irons and woods. The ball is positioned in the center

of the players stance for short irons and putters, more to the front for middle irons and



even more for long irons and woods. The golfer chooses a grip. The golfer chooses a

stroke appropriate to the distance: The drive is used in long distance shots.The

approach is used in long to mid distance shots The chip is used for relatively short

distance shots around the green. The goal of the chip is to land the ball safely on the

green allowing it to roll out towards the hole. The putt is used in short distance shots

on or near the green. The goal of the putt is to get the ball in the hole or as close to the

hole as possible.

5.5 Golf course

A golf course consists of a series of holes, each consisting of a teeing

ground, fairway, rough and other hazards, and a green with a flagstick (pin) and cup,

all designed for the game of golf. A standard round of golf consists of playing 18

holes, thus most golf courses have this number of holes. Some, however, only have

nine holes and the course is played twice per round, while others have 27 or 36 and

choose two groups of nine holes at a time for novelty and maintenance reasons. Many

older golf courses, often coastal, are golf links, of a different style to others. For non-

municipal courses, there is usually a golf club based at each course.

5.6 Par classification

A hole is classified by its par; the number of strokes a skilled golfer should

require to complete play of the hole. For example, a skilled golfer expects to reach the

green on a par-four hole in two strokes (This would be considered a Green in

Regulation or GIR): one from the tee (the "drive") and another, second, stroke to the

green (the "approach"); and then roll the ball into the hole in two putts for par. A golf

hole is either a par-three, -four or -five, rarely -six, very rarely –seven. The key factor

for classifying the par of a hole is the distance from the tee to the green.

- par-three hole: is less than 250 yards (225 metres) in length

- par-four hole : ranging between 251 and 475 yards (225–434 metres)

- par-five hole : being longer than 475 yards (435 metres).

Although uncommon par-six and even par-seven holes do exist, and can

stretch well over 650 yards. The gradient of the course (uphill or downhill) can also

affect the par rating. If the tee-to-green distance on a hole is predominantly downhill,

it will play shorter than its physical length and may be given a lower par rating and the



opposite is true for uphill holes. Par ratings are also affected by factors such as the

placement of hazards or the shape of the green which can sometimes affect the play of

a hole such that it requires an extra stroke to avoid playing into hazards.

Eighteen hole courses may have four par-three, ten par-four, and four par-

five holes, though other combinations exist and are not less worthy than courses of par

72. Many major championships are contested on courses playing to a par of 70, 71, or

72. In some countries, courses are classified, in addition to the course's par, with a

course classification describing the play difficulty of a course and may be used to

calculate a golfer's playing handicap for that given course

5.7 Scoring Count

In every form of play, the goal is to play as few strokes per round as

possible. A "hole in one" (or an "ace") occurs when a golfer sinks his ball into the cup

with his first stroke (a drive from the tee). Scores for each hole can be described as

follows as table 2.1

Table 2.1 The name representative golf score count.

Numeric Term Specific term Definition

−4 Condor four strokes under par

−3 Albatross three strokes under par

−2 Eagle two strokes under par

−1 Birdie one stroke under par

0 Par equal to par

+1 Bogey one stroke over par

+2 Double Bogey two strokes over par

+3 Triple Bogey three strokes over par

+4 Quadruple Bogey four strokes over par



5.8 Golf technique

5.8.1 The griping technique ( Nagao et al.,1997 )

Grip is the first step in learning how to play any golf. As only our hand

creates a connection between our body and the club. The type of the golf grip

technique have 3 types followed as;

- Ten Finger Grip: Known as " the baseball grip ", it generates a lot of

power in the shot. Place the little finger of trailing hand close to the index finger of the

lead hand and cover the lead hands thumb with the center of the palm of trailing hand.

This is mostly suitable for players who experience joint pain, have weak hands or

arthritis as well as for beginners.

- Interlock Grip: This grip makes the club lock in the hand of the player

which results in excellent conversion of energy from body to ball. Take the little

finger on the trailing hand and interlock it with the index finger on the lead hand. The

thumb of lead hand must fit in the center of the palm of the trailing hand. (See image

for details) But one thing about this grip is that you can easily get carried away due to

tightness in grip. The most important thing about this grip is that you have to strike a

perfect balance between your body and hands. This grip is mostly used by people with

small hands, weak forearms and wrists.

- OverlapGrip: The grip creates immense control on the direction as well

as requires less effort to hit the ball to great distances. Take the little finger on the

trailing hand and place it between the index finger and the middle finger on the lead

hand. The thumb of the lead hand should, as usual, fit in the center of palm of the

trailing hand. This balanced grip surely helps in maintaining the equilibrium but is not

suitable for beginners as they can easily lose the grip of leading hand



Figure 2.4 The difference of griping technique in golf ( Nagao et al.,1997 )

5.8.2 Phases of golf swing ( Hume P.A. et al., 2005 )

- Address phase : The address position the arms are hanging to front of

body. Foots are standing width as like the shoulders. Knees are slightly flexed over at

hip and weight distribution evenly between the heels and toes.( Figure 2.3A )

- Back Swing phase : club travel to the back ward direction until the club

is horizontal to the ground on be hide the head position.( Figure 2.3B,C)

- Down Swing phase : from horizontal club overhead acceleration

downward direction to the ball at impact point. ( Figure 2.3D,E

- Follow through phase : the ball contact position to the end of motion,

club place over shoulder. ( Figure 2.3F,G )

A B C D E F G

Figure 2.5 The golf swing phase(A =address)(B,C =back swing)

(D, E =back swing)(F,G =follow through)(Woods, 2001 )



6. Electromyography research in golf

Most of the literature has focused on the EMG analysis of the shoulder and

trunk.Very little research has been conducted on the forearm and lower limb during

the golf swing( McHardy A and Pollard H., 2005 ) and two study compared expert and

novice differences in muscle activity during the golf swing . ( Abernethy B.,1996 ,

Farber A.J., 2009 ) However, the latter paper merely reported that there was larger

variation in muscle activity during golf swing. The injury literature has determined

that the lower back, wrist, and elbow are the three most common sites of golf related

injury ( McCaroll J.R. and Mallon W.J. ) Although there is EMG analysis of back

muscle activity, only two studies has investigated muscle activity of common forearm

and wrist injury sites. ( Glazebrook M.A. et al.,1994 ).

McHardy A. and Pollard H. ( 2005 ) had been review the literature on golf

swing related muscle activity.The literature base on swing phases analysis. In

summary of most muscle activie during the golf swing( table 2.1)



Table 2.2 Summary of most active muscles in whole body during the golf swing

phase data represent in percentage of maximal manual testing( %MMT )

Phase of swing Muscle in left side Muscle in Right side

Back swing Subscapularis (33%) Upper serratus (30%)

Erector spinae (26%)

Abdominal oblique (24%)

Upper trapezius (52%)

Middle trapezuis (37%)

Semimembranosus (28%)

Biceps femoris (27%)

Downswing Pectoralis major (93%)

Vastus lateralis (88%)


Rhomboid (68%)

Adductor magnus (63%)

Levator scapulae (62%)

Gluteus maximus(58%)


Middle trapezius (51%)

Gluteus maximus (100 %)


Pectoralis major (64%)

Upper serratus (69%)


Gluteus medius (51%)

Follow through Biceps femoris (79%)


Infraspinatus (61%)


Semimembranosus (40%)

Adductor magnus (35%)


Subscapularis (64%)

Gluteus medius (59%)


Serratus anterior (40%)



Nirut Sanchai Methods / 26

CHAPTER III

METHODS

1. Study Designed

The study aimed to investigate muscle electrical activity in parallel with its

performance in golfers on laboratory bases. The present study recruited only young-

middle age golfers. This is to avoid effect of age-related deterioration on physiological

system in both strength and coordination. To prevent effect of gender difference on

physical performance, this study recruited only male golfers. Data collection was done

at the same time of the day to prevent circadian variation (Kline et al., 2007). The

study was performed on two separated trials to determine wrist and elbow muscle

performance of both sides: 1). EMG during repeated swing performance and 2).

Isokinetic strength.

2. Materials and methods

2.1 Subjects: Twenty adult right-handed males from The Royal Gems

Golf Club, Nakhorn Prathom, age between 20-40 years, including 10 novices and 10

professional golfers, were voluntary participated in this study. After the interview,

explanation for purposes, testing procedures, benefits and possible risks which might

be found in the study, they filled in specific questionnaires to confirm their

professional level. Physical examination was performed by an investigator who was a

physical therapist, which followed by signing the informed consent form. This

investigation was approved by Mahidol University Ethics Committee on Human

Experiment. Tests were separately performed at Sports Physiology Laboratory,

College of Sports Science and Technology and golf driving room at Salaya Campus,

Mahidol University.



2.2 Inclusion criteria

Subjects were recruited into the study as professional or amateur from the

following criteria:

2.2.1 Beginners or Amateur golfers

Subject was defined as amateur golfer if he had/was

- male, aged between 20-40 years

- golf experience more than 1 year

- handicap range between 19-24

- not participate with other vigorous sports or physical

activities during the period of study.

2.2.2 Professionals golfers

Subject was defined as professional golfer if he had/was

- male, aged between 20-40 years

- documented as Qualified Professional golfer from

Thailand Professionals Golf Association (TPGA)

- continuously practice, more than 3 times per week

- golf experience more than 1 year

- not participate with other vigorous sports or physical

activities during the period of study.

2.3 Exclusion criteria

Subject was excluded from the study when one of the followings was

detected:

- unstable resting/exercise vital signs

- had elbow and/or wrist injury before attending the test

of less than 3 month

- had any orthopedics or neurologic disorders

which might affect the test



3. Variables This study concentrated on muscle performance of flexor and extensor

groups of elbow and wrist. This is based on the basis that golf performance depends

upon these muscles.

a) Fitness laboratory-based variables:

-Anthropometric profile: weight, height, body mass index (BMI), waist

and hip circumferences, waist/hip ratio

-Grip strength

-Isokinetic profiles at 60 degree per sec speed: peak torque, time to

peak torque, work, fatique index

-EMG in parallel with isokinetic profiles: EMG characteristics at MVC

(maximum voluntary contraction)

b) Golf laboratory-based variables

- EMG magnitudes and firing pattern with surface electrodes during golf

swing, expressed as percentage MVC. To get rid of some unfamiliar feeling, subject

was allowed to bring their own golf club for the test. EMG signal was expressed as

raw, root mean square (RMS), frequency domain and amplitude.

4.Instrumentation The following equipments were used to measure physical fitness, strength

and EMG characteristics of muscles:

4.1 Weight scale (Tanita, Japan)

4.2 Hand grip dynamometer (Takei Tokyo, Japan)

4.3 Lange skinfold caliper (Meikosha Co.,Ltd., Tokyo)

4.4 Isokinetic dynamometer (LIDO multi joint II, USA)

4.5 Stethoscope and sphygmomanometer (Spirit ,Australia)

4.6 Telemetry electromyogram (ME 6000, Finland)

4.7 EMG Electrodes, Offset 4 mm. Fitting (AMBU Blue sensor,Denmark )

4.8 Golf club (driver club of individual golfer)

4.9 Golf net with cage size of 4x2 meters



5. Data Collection

5.1 Physical Characteristics:

General physical characteristics were assessed in the upright anatomical

posture. Weight and height were assessed using digital scales then BIM was

calculated. Circumferences of distal arm segment were measured at upper one-fourth

portion of the distance from the medial epicondyle of the humerus to styloid process of

the ulna on the anterior aspect of forearm, and proximal arm segment was measured

over muscle belly of the long head of biceps at a point midway between the acromion

process and the lateral epicondyle. Percentages of body fat were estimated using

skinfold caliper assessed and calculated via seven sites: Triceps, Pectoral, Midaxilla,

Subscapular, Abdomen, Suprailiac and Quadriceps (Jackson and Pollock, 1978).

5.2 Muscle strength data collection:

Isometric grip strength, right side, was measured using hand grip

dynamometer. Bar width was adjusted so that the bar was placed at middle phalanx.

Three trials of maximum effort were performed and expressed as averaged value.

5.3 Electromyographic data collection:

This study used the non-invasive methods of electromyographic data

collection from surface electrodes. First, hair at the selected skin area was shaved off,

the outermost epidermal layer was abraded, then oil and dirt were removed from the

skin with alcohol pad, An electrode pad, with 3 tiny metal electrodes with inter-

electrode space of 10 mm, was placed on target muscle (Thought Technology Ltd.,

2009)

Wrist muscles: Electrodes were placed at 25% of the distance from the

medial epicondyle of the humerus to the styloid process of ulna at the anterior aspect

of the forearm. Wrist extensors electrodes were placed at 25% of the distance from

lateral epicondyle of the humerus to the styloid process of the ulna on the posterior

aspect of forearm (Figure 3.1A).



Figure 3.1 Locations for skin electrodes for wrist (A) and elbow (B) to investigate

electrical activities of flexors and extensors (From: Megawin software V2.3.3, Mega

electronic, Ltd.)

Muscles around elbow: Biceps brachii electrodes were placed over the

midpoint, between the acromion process and the lateral epicondyle, of muscle belly of

the long head of biceps brachii. Triceps brachii electrodes were placed over the muscle

belly of the long head of triceps at a position 30% of the distance between the

acromion process and the olecranon process (Figure 3.1B).

5.4 Analysis of EMG signals

EMG signals were fed into Universal serial bus (USB2.0) interface, which

are then digitized at 1 kHz RAW free data by a personal computer with the Windows-

XP operating system. The impact point was determined using the sound trigger

generator with a condenser microphone sensitive sound, Synchronized to the EMG

instrument. Mean voltages of the signals between the onset of muscle activity and

impact were calculated, and the signal was integrated over this time period.

Baseline EMG signals were recorded while subject sat quietly on a chair

where data were taken over a 1 minute period. Subject was asked to warm up, stretch

and practice with few swings until he felt comfortable for the test. Subject was asked

to perform four swing trials where the sequences of each muscle firing pattern were

recorded. Values were analysed for each trials. As well as the best trial was chosen

from the outcomes for example direction and distance of the ball.



5.5 Isokinetic muscle test:

Isokinetic concentric/concentric performances, of muscles around the wrist

and elbow flexion/extension of both arms, were measured in a controlled position

using isokinetic dynamometer (LIDO multijoint II, USA). Procedures were as follows:

Wrist flexion and extension: While subject sat on the dynamometer chair,

his upper body was firmly strapped to the seat, elbow was adjusted in 90° flexion,

forearm was firmly strapped on the arm pad, so that the axis of motion was aligned at

the medial styloid process. The angular velocity of the test was set at 60

degree/sec.(Aron and David,2000) Subject made firmly grip and performed five

maximal repetitive contractions, the range of highest voltage of the test picked to

average in 500 milliseconds were assumed as MVC for each muscle and peak torque

and power were estimated.

Elbow flexion and extension: Subject sat on the provided chair and faced to

the machine, the upper arm was placed on the seat pad of the machine, chest was

firmly closed to the seat pad using chest strapped. In this position subject’s shoulder

was in 90° flexion, elbow was in 180° extension. The axis of rotation of dynamometer

was aligned with the lateral epicondyle. Subject firmly gripped the arm of

dynamometer (elbow accessory), wrist was in supinated position. The angular velocity

of the test was set at 60 degree/s. (Aaron and David,2000) Subject was performed five

maximal contractions, the range of highest voltage of the test picked to average in 500

milliseconds was assumed as MVC for each muscle and peak toque, power were

collected.

5.6 Statistical Analysis

Statistical analyses were performed using SPSS-13 for Windows. Data

were expressed as means and standard errors of the means (SEM), otherwise will be

stated. Independent t-test will be used to assess differences between the groups. One-

way ANOVA is used to assess differences within the group at different phases.

Significance level is set at < 0.05


Nirut Sanchai Results / 32

CHAPTER IV

RESULTS

1. General characteristics

Twenty male golfers, aged ranges between 21-42 years old, voluntarily

participated in this study. They were divided into 2 groups, professional (n =10) and

amateur (16-24 handicapped, n =10) golfers, based on skill level. General

characteristics, including anthropometric variables, years of experience, resting

isometric muscle performance of each group were listed in Table 4.1. Muscle

performance data were separately measured, at rest, using hand grips (Takei Tokyo,

Japan) and isokinetic dynamometers (LIDO, USA) for both sides of golfer upper

extremities. In the present study, maximum isokinetics performance of muscles were

used as baselines for comparison of both upper limb muscle functions during phases of

golf action. All data were represented as mean ±SEM, otherwise were stated.

1.1 Anthropometry

The values of all general characteristics in both groups such as age,

weight, high, body fat, years of experience and arm sizes were not significantly

different. (p> 0.05) between groups.

1.2 Baseline static hand grip strength

Handgrip strength of both groups were calculated and presented in Table

4.1. Between groups comparison revealed that there was no significant different in

grip strength of the amateur and professional golfers (p > 0.05).

Within group comparison showed no significant difference between right

and left hand grips of either professional or amateur golfers (p > 0.05).



Table 4.1 General characteristics of subjects and maximum isometric handgrip

strength of amateur and professional groups. Values are presented as means and SD.

Variables Professional group Amateur group

Anthropometric data

Age (years) 29.10 ± 6.59 33.3 ± 4.62

Body weight (kg) 70.6 ± 7.50 72.2 ± 16.51

Height (cm) 175 ± 7.78 167 ± 6.67

Body fat (%) 27.75 ± 1.53 28.2 ± 2.90

Experience (years ) 8.6 ± 3.70 7.8 ± 5.43

Arm length (cm)

Right

Proximal

Distal

Left

Proximal

Distal

30.80 ± 2.53

27.75 ± 3.24

30.80 ± 2.53

27.50 ± 3.16

29.55 ± 1.90

25.70±1.86

29.55 ± 1.90

25.65 ± 1.93

Arm circumference (cm)

Right

Proximal

Distal

Left

Proximal

Distal

30.30 ± 2.55

27.75 ± 1.53

30.10 ± 2.40

27.35 ± 1.84

30.10 ± 2.40

27.35 ± 1.84

31.20 ± 3.55

27.85 ± 2.97

Static Muscle Strength (kg):

Left hand grip 50.98 ± 8.34 44.84 ± 8.50

Right hand grip 49.83 ± 9.36 47.61 ± 6.39



1.3 Baseline isokinetic muscle characteristics

Isokinetic performance was conducted at 60 degrees per second in a

con/con (concentric/concentric) mode for elbow flexion/extension, as well as for wrist

flexion/extension of both arms. During isokinetics tests, electrical muscle activities of

biceps brachii (BB), triceps brachii (TB), wrist extensor (WE) and wrist flexor (WF)

of both right and left sides were selectively collected and later used as maximum

references for these muscles participation during golf performance. Between groups

comparisons (Figure. 4.1) showed that there were no significant difference in mean

isokinetic peak torques of right elbow flexion (REF), right elbow extension (REE),

right wrist extension (RWE), right wrist flexion (RWF), left elbow flexion (LEF), left

wrist extension (LWE) and left wrist flexion (LWF) between professional (pro) and

amateur (Am) groups (p>0.05), with the exception of left elbow extension (LEE)

where professional had higher LEE than amateur groups (p<0.05).

Within group comparison in amateur groups showed significant difference

between LEF-LEE, RWE-RWF , LWE-LWF and REW-LWE of (p<0.05).The

comparison in professional groups showed significant difference (p<0.05).between

RWE-RWF, LWE-LWF but not found the significant between right-left peak toque.

2. Performance and contributions of muscles around wrist and elbow during golf

swing

2.1 Electromyographic analysis

Electrical signals of four muscles around wrists and elbows on both sides

were investigated during golf swing phase, including address, back swing, down swing

and follow through. EMG data was shown in three types: raw (1000 Hz sampling

rate), root mean square (RMS, sampling rate 30 Hz) and percentage of maximal

voluntary contraction (%MVC, obtained from isokinetics performance.

Representatives of raw and RMS signals were obtained from the best signals whereas

averaged %MVCs were presented. Changes in these EMG signals were separately

shown for four sub-phases: address, backswing, downswing and follow-through.



Figure 4.1 Means ± SEM of resting isokinetic peak torques (N.m) of muscles around

wrist and elbow joints in professional (Pro) and amateur (Am) golfers. Abbreviations:

LWE (left wrist extension), RWF (right wrist flexion), LEF (left elbow flexion), LEE

(left elbow extension), * significantly different between groups (p<0.05). 1 significantly different within group for agonist-antagonist muscle (p<0.05). 2 significantly different within groups for right-left particular muscle (p<0.05).

2.2 Muscle performance derived from electrical muscle signals.

2.2.1 Biceps Brachii Muscle

2.2.1.1 Raw Electromyography of Biceps Brachii Muscles

Representatives of raw EMG signals, of both right and left biceps brachii

(RBB and LBB respectively), collected from amateur and professional golfers during

golf swing, normalized for same scales for vertical and horizontal axes (Figure 4.2),

revealed the most likely distinctive descriptions as follows:

EMG during address: While there was a silent tracing of Amateur’s raw

EMG, Professional golfer showed somewhat higher of EMG signals of both RBB and

LBB.

EMG during back swing: Apparently both Amateur and Professional

showed muscle activations for both RBB and LBB. However, Pro showed activations

of RBB and LBB muscles almost throughout the entire back swing period while Am

EMGs during the mid latter portions.

*

21 1 1

1

1

Pro



EMG during down swing: Raw EMGs of both groups revealed that the

peak RBB activation appeared at the impact point, the junctions between end of down

swing and beginning of follow through. Greater activations of LBB appeared, for both

groups, exactly at the impact with early activation in Am.

EMG during follow through: Similar RBB EMGs were observed in both

Pro and Am. It appeared that LBB signal in Pro was highly activated than Am where

peak EMG was detected.

2.2.1.2 RMS Electromyography of Biceps Brachii Muscle during

golf swing

Root mean square (RMS) of electromyography data, at 30 Hz sampling

rate after normalized for same scales for vertical and horizontal axes, was represented

in the study (Figure 4.3). Descriptions of data were shown as follows:

EMG during address: Am showed silent tracing of RMS for both

RBB and LBB. On the other hands, Pro showed somewhat higher EMG than Am.

EMG during back swing: Both RBB and LBB of both groups showed

higher EMG during back swing. However, EMG tracings of Pro’s RBB and LBB had

continuous activity throughout the entire back swing period.

EMG during down swing: RMS signals of RBB and LBB, for both

groups, showed tendency of higher values in this phase. Pro showed peaks EMG

exactly at the impact whereas peaks EMG of Am appeared earlier. Pro showed highest

peak RMS for LBB.

EMG during follow through: Pro showed tendency of lower RMS of

RBB signals than LBB which revealed the roles of LBB after the impact. Both RBB

and LBB in Am remained lower in this phase.



Figure 4.2 Representatives, using the same scale, of raw EMG of right biceps brachii

of professional (A, RBB Pro) and amateur (B, RBB Am) and left biceps brachii of

professional (A, LBB Pro) and amateur (B, LBB Am) during 4 sub-phases of golf

swing.

( A ) RBB Pro

( B ) RBB Am

( D ) LBB Am

( C ) LBB Pro

Address Back swing Follow through Downswing



Figure 4.3 Representatives of Root mean square (RMS) electromyography, using the

same scale, of right and left Biceps branchii muscles of Pro (RBB Pro in A; LBB Pro

in C), and Am (RBB Am in B; LBB Am in D) during swing phase.

Address Back swing Downswing Follow through

( A ) RBB Pro

( B ) RBB Am

( D ) LBB Am

( C ) LBB Pro



2.2.1.3 Quantitative contributions of Biceps brachii muscles during

swing phase

The magnitude of involvement during swing phase of muscles in the

present study was expressed as percentage of maximum voluntary contraction (MVC)

obtained from isokinetics torques. According to the following equation, %MCV of

right (RBB) and left biceps brachii (LBB) were separately calculated.

% MVC (biceps brachii) = peak RMS (biceps brachii during swing sub-

phase) * 100 / RMS at MVC (biceps brachii, isokinetics)

Ranges of %MVC contribution of right and left biceps brachii in Pro were

10.48 ±6.30 to 3.51 ±3.61 and Am were 17.11 ±9.46 to 3.01 ±2.09 respectively

(Figure 4.4 A, B). Pro showed changes in RBB, as % MVC, from 3.51 ±3.61 at

address which then increased to 10.36 ±7.42 at back swing, and 10.48 ±6.30 during

down swing and 6.65 ±3.65 during follow through. Am showed changes in % MVC of

RBB from 3.82 ±3.18 at address which then increased to 9.42 ±5.53 at back swing,

and 17.11 ±9.46 during down swing and 9.44 ±6.11 during follow through (Figure 4.4

A). Meanwhile % MVC of RBB of Pro changed from 1.36 ±0.73 at address, 4.27

±2.68 at back swing, 14.52±12.39 during down swing and 14.51±6.02 during follow

through. Am showed changes in % MVC of LBB from 3.15 ±2.69 at address, 3.01

±2.09 at back swing, and 52.82 ±23.69 during down swing and 16.15±8.17during

follow through (Figure 4.4 B).

Between groups comparison of RBB: Similarly, both groups showed the

highest % MVC of RBB and LBB muscles during down swing (Figure 4.4A). There

was no significant different between amateur and professional groups in all sub-phases

of golf swing. Am had higher %MVC of RBB than Pro, however this was not

significantly different (p>0.05).

Within group comparison of RBB: Using %MVC of the address phase

as baseline for comparison, RBB of Pro group revealed the significantly increase

%MVC at back swing (p<0.05) and down swing sub-phases (p<0.05). Comparison

between back swing and down swing of Pro showed similar %MVC (p> 0.05). In Am,

%MVC of RBB showed significantly increased only at down swing (p<0.05) but not

during back swing (p>0.05).



Between groups comparison of LBB: Like the results obtained from the

right side, there was no significant different of LBB between amateur and professional

group in all sub-phases of golf swing (p>0.05) (Figure 4.4B).

Within group comparison of LBB: Compare to address phase, Am group

showed no significant in %MVC (p>0.05) at back swing but, significantly increased

from address phases were down swing and follow through sub-phases (p<0.05).

2.2.2 Triceps Brachii Muscle

2.2.2.1 Raw Electromyography of Triceps Brachii Muscle during

golf swing

Representatives of raw EMG signals collected, from both right and left

triceps brachii (RTB and LTB respectively), muscles from amateur and professional

golfers during golf swing, normalized for same scales for vertical and horizontal axes

(Figure 4.5), revealed the most likely distinctive descriptions as follows:

EMG during address: While there were silent tracings for both RTB and LTB of

Amateur’s raw EMG, Professional golfers showed somewhat higher of EMG signals

of RTB and LTB.

EMG during back swing: Amateur and Professional showed less muscle

activations of RTB, but both gofer groups apparently dominated in LBB activation

(Figure 4.5 C and D). In details, Pro showed continuously activation of LTB while

Amateur’s LTB activated at the last portion of back swing.

EMG during down swing: Raw EMGs of Professional revealed that the

peak RTB activation appeared closer the impact point than peak of Amateur group.

Apparently, Pro used less LTB while Am used much LTB during this phase. Peaks of

LTB in professional appeared in the early portion of down swing whereas that of Am

was observed during the last portion.

EMG during follow through: EMGs of RTB in both Pro and Am were

observed similarly during follow through. In details, EMGs of LBB in Pro were

activated higher and continuously longer than Amateur group.



Figure 4.4 Means electromyographic data of right (A) and left (B) Biceps brachii

muscles during golf swing of amateur and professional golfers. Values are

mean±SEM. a significantly different from initial (address phase) of the same group (p<0.05). b significantly different from previous value of the same group (p<0.05).

A (RBB)

B (LBB)

0102030405060708090

100

Address back swing down swing follow through

%M

VC

Phases

Left BicepsPro

Am

ab a

b

ab

ab

0102030405060708090

100


%M

VC

Phases

Right BicepsPro

Am

a

a a



Figure 4.5 Raw electromyograph, using the same scale, of Triceps brachii muscles of

Pro RTB (A), Am RTB (B), Pro LTB (C) and Am LTB (D).


(A) RTB Pro

(B) RTB Am

(D) LTB Am

(C) LTB Pro



2.2.2.2. RMS Electromyography of Triceps Brachii Muscle during

golf swing

Root mean square (RMS) of electromyography data, at 30 Hz

sampling rate after normalized for same scales for vertical and horizontal axes, were

represented in the study (Figure 4.6). Descriptions of data were shown as follows:

EMG during address: Amateur showed silent tracing of RMS of

RTB but slightly activation of LTB while Pro remarkably activated LTB with quite

silent RTB during address.

EMG during back swing: With silent tracings of RTB in both

groups. LTB of Pro and Am worked differently from RTB in that LTB in Pro was

active throughout back swing period whereas that in Am was activated during the last

half of back swing,

EMG during down swing: Pro showed activation of RTB up to its

peak prior to the impact while LTB in Pro was activated in the lesser extent. RMS of

RTB in Am showed remarkably activation similarly to that in Pro, in that it increased

during down swing. LTB in Am increased in a slightly extent than its RTB.

EMG during follow through: Pro and Am showed tendency of

continuously declined in RMS of both sides of muscle groups. In details, Pro used

both RTB and LTB during follow through whereas Am used only RTB.

2.2.2.3 Quantitative contributions of Tricpes brachii muscles

during swing phase




right (RTB) and left triceps brachii (LTB) were separately calculated.

% MVC (Triceps brachii) = peak RMS (Triceps brachii during swing

sub-phase) * 100 / RMS at MVC (Triceps brachii, isokinetics)

Ranges of %MVC contribution of RTB and LTB Pro were

52.82±23.69 to 3.15 ±2.69 and Am were 68.88±36.82 to 2.9 ±1.59 respectively

(Figure 4.7 A, B). Pro showed changes in % MVC of RTB from 3.15 ±2.69 at address



Figure 4.6 Results obtained from the RMS electromyography, using the same scale, of

Triceps branchii muscles. Abbreviations: (A) Pro RTB, (B) Am RTB, (C) Pro LTB

and (D) Am LTB.


( A ) RTB Pro

( B ) RTB Am

( D ) LTB Am

( C ) LTB Pro



which then increased to 6.75 ±5 .00 at back swing, and 52.82 ±23.69 during down

swing. and 23.47 ±9.79 during follow through Am showed changes in % MVC of

RTB from 2.9 ±1.59 at address which then increased to11.67 ±10.33 at back swing,

and 68.88 ±36.82 during down swing and 27.16 ±21.93 during follow through (Figure

4.7 A).Meanwhile % MVC of LTB of Pro changed from 8.77 ±7.41 at address,

26.35±11.02 at back swing, and 52.70±20.67 during down swing and 16.76±6.00

during follow through. Am showed changes in % MVC of LTB from 7.88 ±6.93 at

address, 21.09 ±15.23 at back swing, and 62.42 ±26.03 during down swing and

27.23±21.31during follow through (Figure 4.7 B).

Between groups comparison of RTB: Both groups showed the

highest % MVC in RTB and LTB muscles during down swing ( Figure 4.7A ).

Comparison between Pro and Am showed that there was no significant different

between amateur and professional groups in all sub-phases of golf swing. Am had,

likely, higher %MVC of RTB than Pro in the down swing phase, however this was not

significantly different (p>0.05).

Within group comparison of RTB: Using %MVC of the address

phase as baseline for comparison, RTB of Pro group revealed the significantly

increase %MVC at down swing (p < 0.05) and follow through (p < 0.05), but

significantly decrease between back swing and follow through sub-phase (p < 0.05). In

comparison between back swing and down swing of Pro showed significantly increase

%MVC (p > 0.05). In comparison between down swing and follow through of Pro

showed significantly decrease %MVC (p < 0.05). In Am, %MVC of RTB showed

similarly as found in Pro group, except Am showed no significant between down

swing and follow through sub- phase.

Between groups comparison of LTB: Like the results obtained

from the right side, there was no significant different of LBB between amateur and

professional group in all sub-phases of golf swing (p>0.05) (Figure 4.7 B).

Within group comparison of LTB: Compare to address phase, Am

group showed significant increase (p <0.05) in %MVC at down swing. Data revealed

that %MVC of LBB in Am progressively and significantly increased from back swing

to down swing (p<0.05) which then significantly decline at follow through (p <0.05).

Similar to results from Am, data from LBB of Pro showed that %MVC were



significantly increased at down swing (p <0.05) and declined at follow through

(p>0.05).

2.2.3 Wrist extensor group

2.2.3.1 Raw Electromyography of Wrist extensor Muscle during

golf swing

Representatives of EMG signals collected from amateur and professional


(Figure 4.8), revealed the most likely distinctive descriptions for right (RWE) and left

wrist extensor (LWE) as follows:

EMG during address: While there were silent tracings of Amateur’s raw

EMGs, Professional golfers showed somewhat higher of EMG signals of both RWE

and LWE (Figure 4.8).

EMG during back swing: Pro showed progressive muscle activation of

RWE throughout the entire period of back swing whereas RWE in Am was activated

just prior to down swing. Apparently, the similar patterns were observed in LWE of

both Am and Pro.

EMG during down swing: Raw EMGs of Pro and Am showed similar

activation in RWE, but in LWE Am revealed likely greater activity than Pro. Am

showed the highest activation of both RWE and LWE in down swing, but not in Pro.

EMG during follow through: EMG of RWE in Pro and Am declined

during follow through. LWE of Pro and Am showed spikes EMGs at the initial portion

during follow through phase, however, the spike was found in RWE of Pro but not in

Am.



Figure 4.7 Means electromyograph of Triceps Brachii muscle during golf swing of

amateur and professional golfers. Right side (RTB in A) and left side (LTB in B). a significantly different from initial (address phase) of the same group (p<0.05). b significantly different from previous value of the same group (p<0.05).

( A ) RTB

( B ) LTB

0102030405060708090

100


%M

VC

Phases

Right TricepsProAm

a

a

b

bb

b

a

a

0102030405060708090

100


%M

VC

Phases

Left Triceps Pro

Am

a

ba

b

b b



Figure 4.8 Raw electromyographic data of wrist extensor muscles during swing

phase. Abbreviations: Pro RWE (A), Am RWE (B), Pro LWE (C) and Am LWE (D).


( A ) RWE Pro

( B ) RWE Am

( D ) LWE Am

( C ) LWE Pro



2.2.3.2. RMS electromyography of wrist extensor muscle during

golf swing



in the study (Figure 4.9). Descriptions of right (RWE) and left wrist extensor (LWE)

data were shown as follows:

EMG during address: Am showed silent tracings of RMS for both RWE

and LWE, but Pro showed higher EMG for both RWE and LWE.

EMG during back swing: Both groups showed progressively increased in

EMG of both RWE and LWE. In details, Pro showed higher muscle activation during

back swing while Am showed less EMG of both RWE and LWE.

EMG during down swing: Both groups had higher muscle activation of

RWE with less activation in LWE during this phase.

EMG during follow through: Pro had higher EMG during follow through

of both RWE and LWE.

2.2.3.3 Quantitative contributions of Wrist extensor muscles during

swing phase




wrist extensor was separately calculated.

% MVC (Wrist extensor) = peak RMS (wrist extensor during swing sub-

phase) * 100 / RMS at MVC (wrist extensor, isokinetics)

Ranges of %MVC contribution of RWE and LWE Pro were 38.22±20.38

to 12.36 ±14.38 and Am were 32.17±15.01 to 6.63 ±4.1 respectively (Figure 4.10 A,

B). Pro showed changes in % MVC of RWE from 12.36 ±14.38 at address which then

increased to 33.66 ±13.30 at back swing, 30.53 ±14.49 during down swing and 22.31

±11.56 during follow through. Am showed changes in % MVC of RWE from 6.63

±4.1 at address which then increased to 22.14 ±10.96 at back swing, 30.45 ±14.16

during down swing and 18.99 ±10.86 during follow through (Figure 4.10 A).

Meanwhile % MVC of LWE of Pro changed from 16.35 ±10.71 at address, 33.26



Figure 4.9 Results obtained from the RMS electromyography, using the same scale, of

wrist extensor muscles in Pro and Am. Abbreviations: Pro RWE (A), Am RWE (B),

Pro LWE (C) and Am LWE (D).


( A ) RWE Pro

( B ) RWE Am

( D ) LWE Am

( C ) LWE Pro



±31.19 at back swing, 36.21±16.29 during down swing and 38.22±20.38 during follow

through. Am showed changes in % MVC of LWE from 9.70 ±4.74 at address, 21.35

±8.58 at back swing, 32.17 ±15.01 during down swing and 24.07±11.15 during follow

through (Figure 4.10 B).

Between groups comparison of RWE: Both groups showed the highest

% MVC in RWE and LWE muscles during down swing (Figure 4.10A). Changes in

%MVC between Pro and Am showed that Pro, likely, had higher %MVC of RWE

than Am in all sub-phase. However, there was significant different between Am and

Pro groups only during back swing phase (p<0.05).

Within group comparison of RWE: Using %MVC of the address phase

as baseline for comparison, RWE of Pro group revealed the significantly increase

%MVC in back swing (p <0.05), and downswing (p <0.05). Am group showed similar

results as those found in pro group in that significantly increase %MVC were during

back swing (p <0.05) and down swing (p <0.05). In follow through, both groups

revealed decreasing of %MVC from down swing but on significant difference was

found (p >0.05).

Between groups comparison of LWE: Pro showed the highest % MVC

of LWE muscles during follow through (Figure 4.10 B) and Am showed the highest %

MVC of LWE muscles during down swing. Comparison %MVC between Pro and Am

showed that Pro had higher %MVC of LWE than Am in all sub-phase but on

significant difference was found (p >0.05).

Within group comparison of LWE: Using %MVC of the address phase

as baseline for comparison, RWE of Pro group revealed no significantly difference of

%MVC in all sub-phase (p >0.05). Am group showed significant increase %MVC

between address and down swing (p <0.05) and between address and follow through

(p <0.05) (Figure 4.10 B).



Figure 4.10 Mean electromyography of wrist extensor muscles during golf swing of

the right (A) and left side (B) in amateur and professional golfers. * significantly different between groups (p<0.05). a significantly different from initial (address phase) of the same group (p<0.05). b significantly different from previous value of the same group (p<0.05).

( A ) RWE

( B ) LWE

0102030405060708090

100


%M

VC

Phases

Right wrist extensorPro

Am

*a

aa

a

0102030405060708090

100


%M

VC

Phases

Left wrist extensorPro

Am

aa



2.2.4 Wrist flexor group

2.2.4.1 Raw Electromyography of Wrist flexor Muscle during golf

swing

Representatives of EMG signals collected from amateur and professional


(Figure 4.11) revealed the most likely distinctive descriptions as follows:

EMG during address: Am showed silent raw EMG of RWF with minor

changes of LWF during address. Pro showed remarkably greater raw EMGs in both

RWF and LWF but it was higher for LWF. EMG during back swing: Both Am and Pro showed continuous

activation of RWF and LWF during back swing. Two peaks of raw EMGs were

observed in both Pro and Am, however, signals in Pro were higher than Am. EMG during down swing: Highest activations of RWF were detected

during the last portion of down swing for both Am and Pro. LWF of Pro was observed

at the early portion but not much change in LWF of Am. EMG during follow through: Both groups showed activations of muscles

during follow through phase. It revealed that activations of both RWF and LWF were

found in Pro but less in Am.

2.2.4.2. RMS electromyography of wrist flexor muscle during golf

swing



in the study (Figure 4.12). Descriptions of right (RWF) and left wrist flexor (LWF)

data were shown as follows:

EMG during address: Silent tracings of RMS EMG signals were detected

in Am during address phase whereas those in Pro were higher for both RWF and

LWF.

EMG during back swing: Low EMGs signal was observed in Am during

back swing. In Pro golfers, higher EMG was detected for LWF with lower EMG for

RWF. EMG during down swing: Peaks EMGs were detected in both groups

during down swing. It appeared that Pro exhibited high EMGs of RWF and LWF in



Figure 4.11 Raw electromyographic data of wrist flexor muscles in professional and

amateur groups during swing phase. Abbreviations: Pro RWF (A), Am RWF (B), Pro

LWF (C) and Am LWF (D).


( A ) RWF Pro

( B ) RWF Am

( D ) LWF Am

( C ) LWF Pro



this phase, however peak EMG of RWF in Pro was during the last portion while that

of LWF in Pro was at the beginning of down swing. EMG in Am was lower than Pro.

EMG during follow through: Pro remained activate flexor muscles

during follow through. EMGs in Am remained low for both RWF and LWF.

2.2.4.3 Contribution of Wrist flexor Muscle during golf swing




wrist flexor was separately calculated.

% MVC (wrist flexor) = peak RMS (wrist flexor during swing sub-phase)

* 100 / RMS at MVC (wrist flexor, isokinetics)

Ranges of %MVC contribution of RWF and LWF Pro were 54.08±25.28

to 9.85 ±9.36 and Am were 34.92±16.36 to 6.75 ±5.51 respectively (Figure 4.13 A,

B). Pro showed changes in % MVC of RWF from 9.85 ±9.36 at address which then

increased to 19.31 ±19.12 at back swing, and 49.85 ±28.25 during down swing. Am

showed changes in % MVC of RWF from 6.75 ±5.51 at address which then increased

to at back swing, and 28.33 ±10.11 during down swing (Figure 4.13 A). Meanwhile %

MVC in LWF of Pro changed from 15.15±11.74 at address, 32.37 ±11.74 at back

swing, and 54.08±25.28 during down swing. Am showed changes in % MVC of LWF

from 9.19±7.48at address, 20.17 ±10.45 at back swing, and 34.92±16.36 during down

swing (Figure 4.14 B).

Between groups comparison of RWF: Both groups showed the highest

% MVC in RWF muscles during down swing (Figure 4.13A). Changes in %MVC

between Pro and Am showed that Pro, likely, had higher %MVC of RWF than Am in

All sub-phase. There was significant different of %MVC between amateur and

professional groups in down swing phase (p <0.05).



Figure 4.12 Results obtained from the RMS electromyography, using the same scale,

of wrist flexor muscles (RWF andLWF) of amateur (Am) and professional (Pro)

golfers during swing phase. Abbreviations: Pro RWF (A), Am RWF (B), Pro LWF (C)

and Am LWF (D).


( A ) RWF Pro

( B ) RWF Am

( D ) LWF Am

( C ) LWF Pro



Within group comparison of RWF: Using %MVC of the address phase

as baseline for comparison, RWF of Pro group revealed the significantly increase

%MVC at down swing (p <0.05) and at follow through (p <0.05) (Figure 4.13A).

There was significant different between back swing and down swing in Pro (p <0.05).

Similar to those found in Pro, Am group had significantly increased %MVC at down

swing (p <0.05), and follow through (p <0.05). Difference between back swing and

down swing in Am was detected (p <0.05).

Between groups comparison of LWF: Both groups showed the highest

%MVC in LWF muscles during down swing (Figure 4.13 B). There was no significant

different between amateur and professional groups in all sub-phase (p>0.05).

Within group comparison of LWF: Using %MVC of the address phase

as baseline for comparison, LWF of Pro group revealed the significant increase

%MVC from address at down swing (p <0.05) (Figure 4.13 B), significantly increased

of %MVC between back swing and down swing (p < 0.05) and, finally, it showed

significantly decreased of %MVC between down swing and follow through (p <0.05)

Am group showed significantly increased %MVC from address and down swing (p

<0.05), back swing and down swing (p <0.05), significantly decreased of %MVC

between down swing and follow trough (p <0.05).



Figure 4.13 Means electromyographic data of right (A) and left wrist flexor (B)

muscles during golf swing of amateur (Am) and professional (Pro) golfers. * significantly different between groups (p<0.05). a significantly different from initial (address phase) of the same group (p<0.05). b significantly different from previous value of the same group (p<0.05).

( A ) RWF

( B ) LWF

0102030405060708090

100


%M

VC

Phases

Right wrist flexorProAm

a

aa

a

b

b*

0102030405060708090

100


%M

VC

Phases

Left wrist flexorPro

Am

b

ba

a

b

b


Fac. of Grad. Studies. Mahidol Univ. M.Sc.(Sports Science) / 59

CHAPTER V

DISCUSSION

The main purposes of this study were 1) to investigate muscle performance

profiles, both sides, of wrists and elbows in professional and amateur golfers during

swing phase, and 2) to define muscle electrical activities of muscles around wrists and

elbows in professional and amateur golfers during golf swing, 3) to compare muscle

performance profiles and muscle electrical activities of muscles around wrists and

elbows between professional and amateur golfers during swing phase.

1. Subject recruitment:

All subjects were participated in this research, age between 20-40 years

which represented the majority age ranges of Thai golfers ( TPGA, 2009 ). Both

groups have continuously played golf for about 7-8 years, which were enough for

learning golf skills. It is reported that golfers who passed PGA approval always exhibit

good skill at driving the ball and reaching the green ( Wiseman et al., 1994 )Therefore,

selection criteria according to TPGA approval in this study is appropriately fit subjects

into amateur and professional groups.

Even though the basic rules of the golf are the same regardless of age and

gender ( Pink and Jobe , 1993 ), the present study had tried to avoid effects of age and

gender by recruiting only males subjects with narrow age ranges between 20 to 40 yrs.

There was no significant different in general factors which are age, height, weight and

% body fat in both amateur and professional groups. All mean values of those factors

were in normal ranges of Thai population ( Lim L et al., 2009 ). However, the percent

body fats of both groups seem to be slightly higher than normal range (Pongchaiyakul

et al., 2005 )


Nirut Sanchai Discussion /60

2. Muscle Function Assessment in Golfers:

In standard golf laboratory (Golf Fitness Laboratory, Neuromuscular

Research Laboratory, University of Pittsburg), the major components for physical

assessments in golfers include (Lephart et al., 2007).

a) balance assessment (using Single-leg balance on a force platform,

performed for 5 trials * 10 s on each leg),

b) isokinetic strength assessment (60 degree/s for strength of the torso

rotation),

c) isometric strength (for hips abduction/adduction)

d) flexibility assessment (using a standard goniometer for passive

examination of hip, torso rotation, active examination for hamstrings

flexibility)

e) swing mechanics (swing kinematics and weight shift were assessed with an

8-camera 3-D motion analysis system and two force plates)

The present study had chosen isokinetic muscle performance as reference

for muscle contributions during swing phase. Isokinetic contraction is the combined

the best features of both isometrics and weight training. It induces muscular

overloading at a constant preset selected speed in which muscle will continuously

moves at its maximal force, muscle contracts at constant speed and constant angular

velocity over the full range of motion. In addition, isokinetic contraction may mimic

the actual speeds of sports-specific activities, swimming in particular, which improve

neuromuscular coordination so that more muscle fibres can be recruited and muscles

can contract more efficiently( Lephart et al., 2007 ). The major disadvantages of

isokinetic exercises are that they can only be performed properly on machines which

are usually expensive. In athletic testing, isokinetic was found to be correlated with

performance than other types of contraction (Anderson et al.,1991). They found that

the best predictor of 40-yard dash time was the right peak isokinetic concentric

hamstring force at 60 degrees/sec (R = .57; p < 0.05) and the best predictor of agility

run time was the left mean isokinetic eccentric hamstring force at 90 degrees/sec (R =

.58; p < 0.05). ( Purkayastha, 2006 ) .Tension developed from isokinetic contraction

was greatest among tensions developed form isometric and isotonic muscle work



(Figure 5.1 ) In addition, isokinetic has been used for athletic training from its

effectiveness over the toher types of training (Mannion,1992).

3. Muscle performance during golf swing:

Golf is not considered as a particularly important in term of energy supply,

therefore, the present study will not concentrate on this sport in either aerobic or

anaerobic aspects. On the contrary, this study will pay attention on muscle activities as

these will considerably create well golf performance. Previous study reported the co-

activation of muscle around the back as key factor for skill and performance in golfers

( Ashish ,2008 )

Figure 5.1 Normalized electromyographic amplitudes (collapsed across muscle,

%MVIC maximal isometric voluntary contraction) versus isotonic load (dotted lines)

and isokinetic contraction (solid lines).

The present study indicates the similarity of muscle strength, hand grip

strength, in both groups in which the values fall in normal ranges of healthy people at

this age (Lindsay, 2006). In addition, golfers in this study are right-handed players.

Normally, the right-handed person has higher grip strength in right than left side,

which is according to the activities in daily life ( Incel et al., 2002 ) Golf is a complex

Isokinetic velocity

Isotonic load

50% 40% 30% 20% 10%

60o/s 120o/s 180o/s 240o/s 300o/s

Nor

mal

ized

ele

ctro

myo

grap

hic

ampl

itude

(%M

VC

)

0%

50%

100%

150%

Isokinetic

Isotonic

Sushmita et al., J Athletic Training 2006;41(3):314–320



sport where golf swing requires coordinated sequences of muscle activity. The present

study indicated that swing phase performance requires appropriate muscle recruitment.

The attention of the present study was only in muscle torque of upper extremities as

baselines of physiologic function of muscles in order to compare between the groups.

Higher left elbow extensor (LEE) peak torque in Pro might be related to muscle used

during golf swing , the left elbow should be straight (triceps brachii isometric action)

from address phase until through the impact point (right-handed swinger) for maintain

a distance between swing axis and radius(golf club) for increase consistency ( Hume

et al., 2005), furthermore the characteristic of professional golfer should be practice

more than amateur, so that LEE might be stronger from training effect ( Gosheger et

al., 2003). However, the isokinetic test obtained from the present study showed the

similar torques of agonist-antagonist muscles around wrist and elbow joints ( Figure

4.1 ). When muscle imbalance took place, previous study reported that it induced

injury to soft tissues around the particular joint ( Murray and Cooney , 1996;

McCarroll , 2001). Wrist injury are the most common occurs in golfers about 13–20%

of all injuries in amateurs and 20–27% of all injuries in professionals in golf injury

epidemiology studies (Gosheger et al., 2003; Grinell K.1999, McCarroll JR.1990). It

was recommended that strengthening of agonist-antagonist combination can prevent

the golf injuries (Westcott et al., 1997; and Yoon S., 1998). The present study shows

that static and isokinetics muscle strengths of professional and amateur golfers

remains the same of either between or within groups.

4. Muscle activation during golf swing:

It is documented that the alternative function within a muscle, activation

and inactivation, might occur throughout swing phase ( Jobe et al.,1986 ) Different

degrees of changes in muscle activation during golf swing had been reported

differently. This may be due to types of maximal muscle contraction used in the study.

For example, it is documented that EMG activities during down swing has the highest

among all sub-phases where the values were ranged from 20.61 to 46.61% MVC using

isometric ( Ashish et al., 2008 ). When MVC was tested using manual muscle testing,

changes in muscle activity may be up to 120% during swing phase ( Farber et al., 2009

). The present study used isokinetic contraction as reference.



In this study, the raw EMG data were normalized to percentage of

maximum isokinetic contraction during swing phase. The data show summary form in

Table 5.1

Table 5.1. Summary on increasing of activities and contributions of muscles around

elbows and wrists in amateur (Am) and professional (Pro) golfers. Meanings: slightly

increase ~ < 10%MVC(+); moderately increase ~ 10-50 %MVC(++); maximally

increase ~ > 50%MVC(+++).

Muscle

Increase (%MVC) during swing phase

Address (Am/Pro)

Back swing (Am/Pro)

Down swing (Am/Pro)

Follow through (Am/Pro)

RBB

LBB

+ / +

+ / +

+ / +

+ / +

++ / +

++ / ++

++ / ++

++ / ++

RTB

LTB

+ / +

+ / +

+ / +

++ / ++

++ / ++

++ / ++

++ / ++

++ / ++

RWE

LWE

+ / ++

++ / ++

++ / ++

++ / ++

++ / ++

++ / ++

++ / ++

++ / ++

RWF

LWF

+ / +

+ / ++

++ / ++

++ / ++

++ / ++

++ / ++

++ / ++

++ / ++

5. Stretch-shortening cycle mechanisms:

Better golf swing performance can be explained using combined stretch-

shortening cycle activities, in which the muscles of the elbows and wrists are

alternately and rapidly stretched prior to shortening. This technique has been used in

sports for years (Wilson et al., 1992). In golf sport, previous studies indicated that such

stretching cycle played critical role during down swing (Cheetham , 2000). This was

proved to enable professional golfers to deliver more power to the shot and higher ball

trajectory( McHardy A., Pollard, H. 2005 ). Muscle activity during the golf swing. The

other major factor which might play roles in golf swing is the angle between hip and

shoulder “X-factor”. It was found no difference in X-factor, between tour



professionals (32°), senior tour professionals (29°) and amateurs (34°) ( McTeigue et

al., 1994 )Unlike the single-handed sports (Figure 5.2 A), stretch-shortening cycle in

golf is more complex in that muscles around elbows and wrists of both sides work in

the combined stretched-shortening cycles. The present study will simplify stretched-

shortening cycle in golf swing using EMG signals (Figure 4.5). For example during

back-to-down swing phase, right triceps brachii changes from concentrically

(shortened) to eccentrically (lengthened) contraction while right biceps brachii works

in an eccentrically to concentrically fashion (Figure 5.2 B). Meanwhile left triceps

brachii works eccentrically to concentrically and left biceps brachii works in an

concentrically to eccentrically fashion.

Figure 5.2 Simple stretched-shortening cycle in single-handed sport (A) and

complex stretched-shortening cycle double-handed sports (B).

Stretched biceps brachii Shortened biceps brachiiA

B

Shortened triceps brachiiStretched triceps brachii



6. Muscle Co-contraction:

Co-contraction is the state where the simultaneous activation agonist and

antagonist muscles around a joint provides the way to adapt the mechanical properties

of the limb to changing both in statics and dynamic motions ( Cothros and Mattar

,2003 )Antagonist co-contraction would appear to be counterproductive, especially for

strength tasks ( Petrofsky et al,. 2006). However, relatively little is known about the

conditions under which the motor system modulates limb impedance through co-

contraction. Muscle co-contraction is found in postural muscular pairs which can be

re-induced even after nerve supply in the area had been cut (Chmielewski et al., 2005;

Granata P, 2000 ).

Co-contraction in golf sport is reported during swing phase where both erector spinaes

exhibit co-contraction ( Lim, 1998 ).Uniqueness of the present study appears in that

there are co-contractions of almost every pairs of muscles around wrist and elbow.

These are detected in both Pro and Am but at different patterns and magnitudes. For

example, Pro an Am exhibit remarkably bicep-triceps brachii co-contraction, of both

right and left sides, during down swing (Figure 4.4 and 4.7) where triceps brachii is

activated in a greater extent than biceps brachii. The similar co-contraction appears in

the wrist flexor and extensor during down swing phase (Figure 4.11 and 4.14) where

wrist flexor is activated in a greater extent than wrist extensor.

7. Reciprocal Inhibition:

Reciprocal inhibition describes muscles on one side of a joint relaxing to

accommodate contraction on the other side of that joint. During particular movement

where one muscle is shortening the opposite must be inhibited. When reciprocal

inhibition does not exist, a common soft tissues tearing can occur ( O’Corner,1993 )

This type of co-contraction is generally exhibited during physical activities like

walking and running where muscles that oppose each other are engaged and

disengaged sequentially to produce coordinated locomotion.

It is documented that when co-contraction takes place during movements, as a

result precise movement is induced under controlled of higher center (Meulenbroek ,

2005 ).This becomes more critical during rapid motion, like golf, in that the body and



higher center must be cooperatively worked to control both static and dynamic

postural changes.

8. Limitations of the current study

The limitation of this study involves the testing conditions; all subjects hit

golf balls in laboratory from artificial turf to the net, and only a driver was used to hit

balls. The EMG findings may be different if use in varies type of golf club.The vedio

camera was limited in record frame rate at 30 fps,cause to define the golf swing phase

that only 4 phases and the part of isokinetic test should be add wrist pronation /

supination position ,because wrist action during golf swing also combine with

pronation and supination of radio ulnar joint ( Hume et al., 2005 ).



CHAPTER VI

CONCLUSION

In conclusion, the present study has contributed for the better

understanding on differences of performance found in professional and amateur

golfers during swing phase in that:

1) This study demonstrated the similarities of baseline peak torques performance

profiles on both sides of wrists and elbows in professional and amateur golfers.

2) This study demonstrated the different levels of electrical activity of muscles

around wrists and elbows during golf swing, in which muscle electrical

activities in professional are, likely, higher than amateur golfers.

3) This study uniquely indicated the different levels of dynamic co-contraction of

agonist-antagonist muscles around wrists and elbows during golf swing.


Nirut Sanchai References / 68

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APPENDICES



APPENDIX A

แบบฟอรมยนยอมใหทาการวจย โดยไดรบการบอกกลาวและเตมใจ (Informed Consent Form)

การวจยเรอง การศกษาการทางานและคลนไฟฟาของกลามเนอรอบขอมอและขอศอกในนกกอลฟอาชพ และนกกอลฟสมครเลน กอนทจะลงนามในใบยนยอมทใหทาการวจยน ขาพเจาไดรบการอธบายจากผวจยถงวตถประสงคของการวจย วธการวจย อนตราย หรออาการทอาจเกดขนจากการวจยหรอจากยาทใช รวมทงประโยชนทจะเกดขน จากการวจยอยางละเอยด และมความเขาใจดแลว ผวจยรบรองวาจะตอบคาถามตางๆ ทขาพเจาสงสยดวยความเตมใจ ไมปดบงซอนเรนจนขาพเจาพอใจ ขาพเจามสทธทจะบอกเลกการเขารวมโครงการวจยนเมอใดกได และเขารวมโครงการวจยน โดยสมครใจ และการบอกเลกการเขารวมการวจยน จะไมมผลกระทบตอตวขาพเจาแตอยางใด ผวจยรบรองวาจะเกบขอมลเฉพาะทเกยวกบตวขาพเจาเปนความลบ และจะเปดเผยไดเฉพาะในรปทสรปผลการวจย การเปดเผยขอมลเกยวกบตวขาพเจาตอหนวยงานตาง ๆ ทเกยวของ กระทาไดเฉพาะกรณจาเปน ดวยเหตผลทางวชาการเทานน ผวจยรบรองวาหากเกดอนตรายใด ๆ จากการวจยดงกลาว ขาพเจาจะไดรบการรกษาพยาบาลโดยไมคดมลคาตามมาตรฐานวชาชพ ผวจยรบรองวาหากมขอมลเพมเตมทสงผลกระทบตอการวจย ขาพเจาจะไดรบการแจงใหทราบโดยไมปดบงซอนเรน ขาพเจาไดอานขอความขางตนแลว และมความเขาใจดทกประการ และไดลงนามในใบยนยอมน ดวยความเตมใจ ลงนาม ......................................................................................... ผยนยอม วนท…………………………………………………… ลงนาม...........................................................................................ผทาวจย วนท.................................................................................


Nirut Sanchai Appendices / 78

APPENDIX B

ID……………. แบบสารวจขอมลเบองตน

วนท…………………….

ชอ-สกล…………………………………………………………..

นกกอลฟอาชพ นกกอลฟสมครเลน handicap…………… วนเดอนปเกด………………………….. อาย …………….. มอขางทถนด………………… ระดบการศกษา ตากวาปรญญาตร ปรญญาตร หรอ เทยบเทา สงกวาปรญญาตร เรมเลนกอลฟมาแลว …………. ป การฝกซอมปจจบน ……………….. วน/สปดาห ในปจจบนทานเลนกฬาประเภทอน ๆ ดวยหรอไม ……………. ………..จานวน…………..ครง/สปดาห ในปจจบนทานมอาการบาดเจบในสวนใดบาง…………………………………………………………….. --------------------------------------------------------------------------------------------------------------------------- Health and physical status Resting hart rate ……………..bpm. BP………………..mm.Hg. Weight………………Kg. high………….cm. grips strength right .…………….… Kg

Left …………. …... Kg. Arms size

Sum of seven skin fold(mm) Triceps Pectoral midaxilla subscapular abdomen suprailiac Quadriceps

Circumference Distal arms Proximal Right Left Arm length Distal Proximal Right Left



APPENDIX C

ETHICAL COMMITTEE APPROVAL


Nirut Sanchai Biography / 80

BIOGRAPHY

NAME Mr. Nirut Sanchai

DATE OF BIRTH 21 September 1983

PLACE OF BIRTH Chiang Mai, Thailand

INSTITUTIONS ATTENDED Chiang Mai University, 2001-2005:

Bachelor of Science ( Physical therapy )

Mahidol University, 2005 -2009:

Master of Science (Sports Science)

RESEARCH GRANT Support in Part by the Thesis Grant, Faculty of

Graduate Studies, Mahidol University

ADDRESS 153/2 Kong-sai Rd.,

Tumbol Watkaet, Umpure Muang, Chiang mai

Thailand 50000

Telephone 0-8975-7747-3


study of how the muscles around the wrist and...

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