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THE UNIVERSITY OF HONG KONG

LIBRARIES

Hong Kong Collectiongift from

Hong Kong Sports Development Board

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Preface

Taekwondo is a free-fighting, combat sport that is popular in Hong Kong, it is an international sport,with over 18 million participants worldwide, and is one of the new Olympic sports in the Sydney 2000Games. Taekwondo is well-known for its fast, high and spinning kicks, and good kicking technique isan essential part of the sport.

Using biomechanical analysis, Dr Hong and his team studied athletes' kicking technique and thendesigned a training programme that strengthened the leg muscles used during high-speed kicks. Thestudy was carried out in association with Lok Wah Taekwondo Club and SDB acknowledges the Club'scontribution to the study.

The Hong Kong Sports Development Board (SDB) commissioned this study as part of its sportsscience and medicine research programme, and it provides another example of how scientific studycan help Hong Kong's athletes improve their training and competitive performance.

Biomechanical Analysis of

Taekwondo Kicking Technique,

Performance & Training Effects

The study was carried out for SDB by:

Dr Youiian Hong (Principal Investigator), Associate Professor, Department of Sports Scienceand Physical Education, The Chinese University of Hong Kong

Leung Hing Kam, Chief Coach and Chairperson of Lok Wah Taekwondo Club

Luk Tze Chung, Jim, Department of Sports Science and Physical Education, The ChineseUniversity of Hong Kong

SDB Research Report - No. 2©SDB, August 2000

FINAL REPORT

For the Project

Biomechanical Analysis of Taekwondo Kicking

Technique, Performance and Training Effects

Submitted to

Hong Kong Sports Development Board

By

Youlian Hong, Ph.D., Associate Professor

Department of Sports Science and Physical Education

The Chinese University of Hong Kong

. Leung King Kam, Chief Coach and

Chairperson of Lok Wah Taekwondo Club

Luk Tze Chung, Jim

Department of Sports Science and Physical Education

The Chinese University of Hong Kong

Abstract

The purpose of this study was to investigate the kicking technique of Hong Kong

Taekwondo athletes and to develop a well-designed training protocol to improve the

performance of Taekwondo athletes in Hong Kong, A pre- and post-test design was

employed in this study to examine the effectiveness of a training protocol that was

based on the outcome of the pre-test. For each test session, the Taekwondo frontal

attack kicking technique, such as sidekick, pushing kick, slap kick and back kick, was

investigated. Kicking performance was video filmed and the muscle activities were

recorded by an electromyography (EMG) system. Based on the recorded EMG signals

and the EMG signals obtained from measuring the maximum voluntary contraction

(MVC) before the test trial, the 4>efcSafege !MVC (%MVC) was derived. The'

/', —kinematics of each kicking movement ^ece^obj^ined by digitising and analysing the

*'*8:i$&'recorded video tapes on a motion analysis system. The results showed that there were

significant differences in kicking time among different styles of kicking (p<.001) and

different heights of kicking (p<.001). However, there was no significant difference

in kicking time between different preparation forms. The front turning kick to the

waist level with standing preparation form was significantly faster (0.70 ± .098s) than

the other styles of kicking. However, the one-step sidekick to the head level with

standing preparation form was significantly slower (1.09 ± ,119s) than other styles of

kicking. The muscle activity during kicking was significantly different among

selected muscles (p<.001). The vastus lateralis and tensor fasciae latae showed

significantly higher average activity when compared with other selected muscles. The

average muscle activity for the tensor fasciae latae and the vastus lateralis was 133.12

± 77.55%MVC and 250.44 ± 182.28%MVC, respectively. This value for sartorius,

rectus femoris and vastus medialis was 42.33 ± 14.98%MVC, 66.84 ± 31.31%MVC

and 75.98 ± 41.19%MVC, respectively. Muscle activity of hamstrings can be

represented by semitendinosus and biceps femoris. The activity level of these two

muscles was 43.53 ± 15.43%MVC and 47.14 ± 28.29%MVC, respectively. The

isokinetic training protocol was designed with knee concentric extension/flexion at

240deg/s, 20 repetitions in each set, 5 sets for each session, 3 sessions weekly. The

isokinetic concentric knee extension peak torque at 240 deg/s showed significant

increase from pre- (108.83 ± 16.95 Nm) to post-test (117.83 ± 18.99 Nm) for the

training group. It was concluded that isokinetic training at 240 deg/s angular velocity

can increase the muscle peak torque of concentric knee extension at that velocity.

Objectives

The objective of this study was to investigate the available methods for analysing

kicking technique and performance of Taekwondo athletes. By using biomechanical

analysis, a systematic measurement of Taekwondo kicking technique and

performance could be developed. The results obtained from this study could be used

to develop an advanced protocol to improve the kicking technique and performance of

Taekwondo athletes in Hong Kong. The ultimate target is to increase the competitive

ability of Hong Kong Taekwondo athletes.

Background

Taekwondo is one of the popular sports in Hong Kong. Moreover, it will become a

formal event in the Sydney 2000 Olympic Games. Therefore, there is a need to place

considerable attention on this sport. Taekwondo was originally developed as a

fighting art in Korea and has been distributed all over the world. With over 18 million

practitioners worldwide, today Taekwondo is generally regarded as the most popular

event of the martial arts. When reviewing the development of Taekwondo in various

countries, Mainland China would be a good example, as it has forcibly promoted

Taekwondo in the last three years. The aim being to raise the level of Taekwondo in

Mainland China to world standard.

Biomechanics methods have been successfully used to improve traditional training

methods and athletic performance. Traditional training methods for Taekwondo have

been developed for a decade in Hong Kong. However, the scientific study of

Taekwondo was lacking. To improve the competitive ability of Hong Kong

Taekwondo athletes in world level competition, it is necessary to develop applicable

scientific training methods. The systematic and scientific methods that were

developed in this study will be useful in evaluating the performance and technique of

Taekwondo athletes in Hong Kong.

In this study, a biomechanical method for evaluating Taekwondo kicking technique

and performance was developed. The kicking speed, reaction time, and muscle group

recruitment for kicking was measured. Taekwondo is a sport that focuses on using

appropriate kicking technique. The proper use of the lower limb muscles when

kicking is an important factor affecting the overall performance of Taekwondo

athletes.

Based on the results of the evaluation, a scientific training protocol was developed.

The training protocol focused on the kicking speed, force produced and strengthening

exercise for the prime muscles. A pre- and post-test experiment was performed, with

an eight-month training period in between, to evaluate whether or not the athletes'

kicking technique and performance had been improved.

The results of the present study are described in two parts. The first part is the

biomechanical analysis of Taekwondo kicking technique and performance. The

analysis of technique and performance included kicking speed, kicking time duration,

and muscle group recruitment. The second part is the development of a scientific

training protocol. The design of the training protocol was based on the information

obtained from the technique and performance evaluation in the pre-test. The protocol

aimed to provide a specialised training technique for increasing muscle strength and

reaction time during kicking.

Methodology

Twelve subjects were recruited in Lok Wah Taekwondo Club. The Taekwondo

practising history of the athletes was recorded in terms of length and frequency of

training. General anthropometric parameters (height, weight), and physical fitness

level of all subjects were measured (Table 1). Each subject gave informed consent and

the study was explained to them before they participated in the experiment.

Table 1

Subjects Information

Age (year)

Weight (kg)

Height (cm)

Shoulder width (cm)

Years of training (year)

Frequency of training (hr/week)

Percentage of body fat (% fat)

Flexibility (cm)

Handgrip strength (kgf)

Mean

25.25

62.56

170.78

33.88

7.50

2.67

11.28

40.13

40.50

SD

8.34

5.17

6.42

1.73

2.50

1.87

4.29

5.97

5.95

Note, The percentage of body fat was calculated by using the 7-skinfold sites with

ACSM provided equation. Takei handgrip dynamometer was employed to measure

the handgrip strength. ACUFLEX sit-and-reach box was employed in flexibility

measurement.

In order to find out the prime muscles used in kicking, a pilot test was done before the

beginning of the testing sessions. The results of the pilot test were then used to

investigate the activities of eight muscle groups. The muscle activity was expressed as

a percentage of Maximum Voluntary Contraction (%MVC).

A pre- and post-test design was used in this project to examine the effectiveness of the

training protocols. For each (pre- and post-) test session, the maximum voluntary

isometric contraction test was conducted before the kicking trial started. Afterwards,

each subject was asked to perform several kicking skills, including sidekick, pushing

kick, slap kick and back kick. The performed skills were recorded by video filming

and EMG measurement simultaneously. The recorded videotapes were then digitised

on a motion analysis system.

The data collected from the pre-test were used as a baseline to design the training

protocol, which focused on an exercise to strengthen the major muscles used during

kicking and technique training.

The subjects were divided into two groups, training group and control group. After

the pre-test, the training group underwent the training programme, whereas the

control group was only asked to conduct the post-test without any special training.

Motion analysis. Two Peak high-speed video cameras with 120 Hz in filming rate

and SOOHz in shutter speed were positioned at a distance of 5 metres from the subject

to record the subject's movements (Figure 1). An 800W lamp was used to increase the

light intensity during the filming. The recorded video tapes were then digitised and

analysed on the 3-D module of the motion analysis system (BAS), To facilitate the

transformation of image data from 2-D to 3-D, a 3-D calibration frame, two metres

high, was used (Figure 3). A 21-point biomechanical model of an athlete's body was

7

used to perform the motion analysis. The output data from the motion analysis

included time characteristics during kicking.

i:

Figure 1. The Peak high-speed video camera was placed at a distance of 5 metres

from the subject.

Figure 2. The 800W lamp was used to increase the light intensity during the

video filming.

Figure 3. A two-metre high frame was employed for 3-D motion analysis

calibration.

EMG analysis. The EMG activity of the muscles involved in kicking was

recorded with surface electrodes (silver / silver chloride, T-OO-S, Medicotest,

01stykke, Denmark) attached to the skin in a standardised manner: in the direction of

the muscle fibres, with an inter-electrode distance of 3 cm. Before attaching the

electrodes, the skin was shaved and rubbed with alcohol in order to lower the skin

resistance. EMG electrodes were attached to several sites on the dominant leg (Figure

4).

The muscle groups included:

• Sartorius (Ch. 1)

• Rectus femoris (Ch. 2)

• Tensor fasciae latae (Ch. 4)

• Vastus lateralis (Ch. 5)

• Vastus medialis (Ch. 3)

• Semitendinosus (hamstrings) (Ch. 6)

• Biceps femoris (hamstrings) (Ch. 7)

• Gastrocnemius (Ch. 8)

• Shoulder (ground)

10

Figure 4. The EMG electrodes were placed on the selected muscles of the lowerextremity.

After attaching the electrodes, the electrode cables were connected to the electrodes at

one end and to the pre-amplifier at the other end. The pre-amplifier was close to the

pads, eliminating the artifacts caused by subjects' movements. The pre-amplifier was

fixed on the skin with paper, adhesive, tearable tape (3M, Transpore) to prevent any

vibration of the amplifier.

1 1

In order to express the muscular activity of a muscle as the percentage of the MVC of

that muscle, the measurement of EMG signals associated with the MVC EMG was

conducted before the kicking trial began (Figure 5 and 6). The MVC EMG was

employed in the later calculation of %MVC, which represented the muscular activities

of the selected muscles.

Figure 5. The figure shows the test of isometric maximum voluntary contraction

with knee flexion.

I mre ••!_.. * * y>

Figure 6. The figure shows the test of isometric maximum voluntary contraction

with knee extension.

During the collection of EMG signals, the signals from the electrodes were pre-

amplified, and transmitted through telemetric radio transmitters (915 Transmitter Unit,

TELEMG, Italy). These signals were received by the receiving unit (920 Diversity

Data Receiver, TELEMG, Italy), and passed through the optical fibre to the main unit.

The main unit then amplified the signal by 1000 times.

The quantitative analysis of the EMG signals was performed by an IBM-compatible

computer. The raw EMG signals were low-pass (600 Hz) and high-pass (10 Hz)

filtered and simultaneously A/D-converted (PCI-6071E, National Instruments, USA)

at a sample rate of 2000 Hz for each channel. The rectification of EMG signal and

12

integration of EMG signal were calculated by data acquisition and analysis software

(LabView, USA), with simultaneous visual control of the signals on the computer

display.

Figure 7. The figure shows the connection box between the A/D converted card

and signal from the instruments.

The information provided by EMG signal analysis included the degree of contraction

of the selected muscles and the priority of muscle recruitment during kicking. This

important information was then used in the design of the training protocol.

13

Kicking Test. After conducting the MVC test, the subject was asked to perform

several sets of kicking in randomised order. The kicking style included the

preparation form of kicking, kicking to the head level and kicking to the waist level in

different styles of kicking (Table 2 and Figure 8, 9).

Table 2

The Kicking Stvle Preformed i n the Kicking Test

Kicking style

1 Turning kick

2 Front turning kick

3 Reverse kick

4 One step side kick

5 Front side kick

6 Back kick

7 Pushing kick

8 Slap kick

Figure 8. The figure shows the standing preparation of kicking. The subject willuse his back leg for kicking.

14

f!

Figure 9f The figure shows the pushing kick at the waist level. The number "1"means the first trial of this style of kicking and the letter "D" indicates the

kicking sequence belongs to D series.

Training prQtocol The design of the training protocol focused on two areas. The first

one was muscle strength. The results obtained from EMG analysis provided the

information about the muscle activity during kicking. According to the degree of

contraction, a muscle strengthening exercise was designed by using the Cybex NORM

(isokinetic machine). The second focus was the techniques of kicking. The results

obtained from motion analysis provided kinematics information on kicking. Such data

were useful in improving the kicking technique and kicking effectiveness.

15

I*-*-'

Figure 10. The figure shows the condition of training with isokinetic concentric

knee extension/flexion at 240 deg/s.

The training protocol was executed for a period of eight months. The experimental

group added the new protocol to their usual training regime, while the control group

kept to their usual training regime. The post-test session was arranged immediately

after this period to examine the

16

Results

Parti

Biomechanical analysis of kicking

Kicking analysis

ANOVA was employed to examine the difference in the timing of kicks of different styles

and heights.

The results showed that there were significant differences in kicking time for different styles

of kicking (p<.001) and different kicking heights (p<.001). However, there were no

significant differences in kicking time between different preparation forms (Table 3). Table 4

shows the descriptive statistics of the kicking time for different preparation forms and styles.

The graphical presentation of the kicking time for different preparation forms and styles is

demonstrated in Figure 11.

One step

o<DC/3

5

1—'—• rKicking Styles with Standing Form before Kicking

Figure 11, The graphical presentation of kicking time (±SD) for different kicking styles.

17

Table 3

*v>-junj ui ni-iv-f T j-f. 111 i».i»-i^jii5 j m»v *v* t

Height Levels and Preparation Forms

Source Type III df Mean F Sig.

Sum of Square

Squares

Corrected Model

Intercept

FORM

LEG_FORM

KICKING

KICK_LEV

FORM * LEG_FORM

FORM * KICKING

LEG_FORM * KICKING

FORM * LEG_FORM * KICKING

FORM * KICKJLEV

LEG_FORM * KICK_LEV

FORM * LEG_FORM * KICK_LEV

KICKING * KICKJLEV

FORM * KICKING * KICKJLEV

LEG_FORM * KICKING * KICK_LEV

FORM * LEG_FORM * KICKING *

KICKJLEV

Error

Total

Corrected Total

2.390

136.743

0.000

1.031

0.249

0.350

0.007

0.002

0.000

0.000

0.000

0.002

0.000

0.000

0.000

0.000

0.000

1.892

167.216

4.282

18

1

1

2

5

1

2

4

0.

0 .

0.

2

0.

10.

0.

0.

209

228

227

0.133 14.665 0.000

136.743 15105.941 0.000

0.000 0.005 0.941

0.516 56.967 0.000

0.050 5.493 0.000

0.350 38.710 0.000

0.004 0.404 0.668

0.000 0.047 0.996

.

0.001 0.117 0.890

0.000 0.004 0.953

.

0.009

Note. Df = degree of freedom; F = F value; FORM = the preparation form of kicking that

consists of jumping and standing; LEGJFORM = the position of kicking leg before kicking

that consists of front and back; KICKING = the styles of kicking that is shown in Table 2;

KICKJLEV = the height level of kicking that consists of subject's head height and waist

height.

18

Table 4

Kicking Styles

Jumping

Back leg

Back kick

Turning kick

Pushing kick

Slap kick

Front leg

Turning kick

Side kick

One step

Side kick

Standing

Back leg

Back kick

Turning kick

Pushing kick

Slap kick

Reverse kick

Front leg

Turning kick

Side kick

One step

Side kick

Height level

Low

Low

Low

Low

Low

Low

Low

Low

Low

High

Low

Low

High

Low

High

Low

High

Low

High

Mean (sec)

N=12

0.870

0.770

0.830

0.780

0.740

0.730

0.960

0.890

0.800

0.900

0.840

0.790

1.020

0.720

0.850

0.700

0.840

0.960

1.090

S.D.

0.065

0.070

0.076

0.084

0.073

0.091

0.114

0.074

0.087

0.085

0.100

0.076

0.125

0.099

0.107

0.098

0.115

0.116

0.119

19

The front turning kick to the waist level with standing preparation form was significantly

faster (0.70 ± .098s) than the other styles of kicking. The one-step side kick to the head

level with standing preparation form was significantly slower (1.09 ± .119s) than the other

styles of kicking.

Moreover, the use of the front leg was significantly faster than the use of the back leg for

kicking (p<.001). The kicking time, when kicking to the subject's waist level, was

significantly shorter than a kick to the subject's head level (p<.001).

The kicking height showed significant effects on kicking time. The kicking time to a higher

level was significantly longer than that to a low level (p<.001).

EMG analysis

Table 5 shows the descriptive statistics of muscle activity in terms of %MVC for each

selected muscle during kicking.

Table 5

Descriptive Statistics of Each Selected Muscle Activity (%IVIVC) During Kicking

Mean (%MVC) S. D.

N = 228

CHI

CH2

CHS

CH4

CHS

CH6

CH7

CHS

42.33

66.84

75.98

133.12

250.44

43.53

47.14

77.50

14.98

31.31

41.19

77.55

182.28

15.43

28.29

52.46

Note. CHI = Sartorius; CH2 = Rectus femoris; CHS = Vastus medialis; CH4 = Tensor fasciae

latae; CHS = Vastus lateralis; CH6 = Semitendinosus; CH7 = Biceps femoris; CHS =

Gastrocnemius.

ANOVA was employed to examine the difference in muscle activity during kicking (Table 6).

20

The statistical analysis showed that there was a significant difference in muscle activity

among the selected muscles during kicking (p<.001).

The vastus lateralis and tensor fasciae latae showed significantly higher muscle activity

during kicking when compared with other selected muscles. The muscle activity of the tensor

fasciae latae was 133.12 ± 77.55%MVC and the muscle activity of the vastus lateralis was

250.44 ± 182.28%MVC during kicking.

The muscle activity of sartorius, rectus femoris and vastus medialis was 42.33 ±

14.98%MVC, 66.84 ± 31.31%MVC and 75.98 ± 41.19%MVC, respectively, during kicking.

Muscle activity of the hamstrings during kicking can be represented by the semitendinosus

muscle and the biceps femoris, with the activity level of these muscles 43.53 ± 15.43%MVC

and 47.14 ± 28.29%MVC, respectively.

Figure 12 is the graphical presentation of muscle activity among selected muscles during

kicking.

Note. Channel numbersare:1 = Sartorius2 = Rectus femoris3 = Vastus medialis4 = Tensor fasciae latae5 = Vastus lateralis6 = Semitendinosus

6*|£|"ocd

"oC/3

1

500;450;400;35qsoq250;200;i5trioq5(T

1 2 3 4 5 6 7

Channel number

Figure 12. The graphical presentation of muscle activity %MVC (±SD) during kicking.

21

Table 6

Source FACTOR1

FACTOR1 Linear

Quadratic

Cubic

Order 4

Order 5

Order 6

Order 7

Error(FACTORl) Linear

Quadratic

Cubic

Order 4

Order 5

Order 6

Order 7

Type III Sum df Mean Square F Sig.

of Squares

38164.95

2377499.31

41730.89

2222649.56

379819.04

1442389.26

1414565.28

374399.21

2242314.66

327906.05

1887336.09

673115.69

1380244.64

1507788.46

1

1

1

1

1

1

1

227

227

227

227

227

227

227

38164.95 23.14

2377499.31 240.69

41730.89 28.89

2222649.56 267.33

379819.04 128.09

1442389.26 237.22

1414565.28 212.97

1649.34

9878.04

1444.52

8314.26

2965.27

6080.37

6642.24

0.000

0.000

0.000

0.000

0.000

0.000

0.000

Note. FACTOR1 represents the different activity level among different selected muscles

during kicking.

Training programme

According to the results of the analysis of kicking, relatively low muscle activity was found

in the quadriceps and hamstrings. It is likely that the lower muscle activity of the quadriceps

is due to the rapid movement of knee extension during kicking that, in turn, results in less

muscle fibres being recruited. On the other hand, the quadriceps seems to be the prime mover

in knee extension during kicking. According to this finding, we designed a training protocol

that contains special training of knee extension and flexion under high-speed condition, in

order to increase the muscle activity of the quadriceps during kicking.

The isokinetic training protocol contained knee concentric extension/flexion contraction at

240%, 20 repetitions in each set, 5 sets for each session, 3 sessions weekly.

22

Part II

Training effect

Table 7 shows the descriptive statistics of the isokinetic concentric contraction peak torque at

240 deg/s of knee extension before and after training for the control and training groups.

The isokinetic concentric knee extension peak torque at 240 deg/s changed from 108.00 ±

14.93 Nm in the pre-test to 103.50 ± 11.43 Nm in the post-test for the control group. The

isokinetic concentric knee extension peak torque at 240 deg/s showed significant increase,

from 108.83 ± 16.95 Nm in the pre-test to 117.83 ± 18.99 Nm in the post-test for the training

group.

Table 7

Descriptive Statistics of Isokinetic Concentric Contraction Peak Torque at 240 deg/s of

Knee Extension Before and After Training for the Control and Training Groups

GROUP

PRE

Control

Training

POST

Control

Training

Mean (Nm)

N = 6

108.00

108.83

103.50

117.83

S.D.

14.93

16.95

11.43

18.99

Note, PRE = result from the pre-test; POST = result from the post-test; Nm = Newton meter.

ANOVA was employed to examine the effect of the training programme on the isokinetic

strength of knee extension at 240 deg/s. The results of the statistical analysis showed that

there was a significant increase in the peak torque of the isokinetic concentric contraction at

240 deg/s at knee extension (p<.05).

23

Figure 13 shows the graphical presentation of isokinetic concentric contraction peak torque at

240 deg/s of knee extension before and after training for the control and training groups.

140-

I-

CUo'i>I

120-

10O

| | Control group| | Training group

Pre-test Post-test

Figure 13. Graphical presentation of isokinetic concentric contraction peak torque at

240 deg/s of knee extension before and after training for the control and training

groups.

Table 8 shows the results of ANOVA in isokinetic concentric contraction peak torque at 240

deg/s of knee extension with significant change (p< .05).

Table 8

Extension

Source

PREPOST

PREPOST * GROUP1

Error(PREPOST)

PREPOST

Linear

Linear

Linear

Type HI Sum df

of Squares

30.375

273.375

345.75

Mean F

Square

1 30.375

1 273.375

10 34.575

Sig.

0.879 0.371

7.907 0.018

24

Discussion and Conclusion

The results of this study were divided into two parts. The first part was the biomechanical

analysis of Taekwondo kicking and the second part was the evaluation of the isokinetic

training..

In the biomechanical analysis of Taekwondo kicking, the kicking time and the muscle

activity were measured and ANOVA was employed to examine the difference among

different kicking styles, The kicking time between different preparation forms showed no

significant difference, indicating that, to perform a kick, different preparation movements will

not result in different kicking times.

In the real Taekwondo competition, athletes always keep their body moving during the game.

If the kicking time was the same for different preparation forms, then why do athletes move

their body before attacking? Can they perform the same kicking performance with standing

or jumping preparation form before kicking? It is common knowledge that in order to keep

moving before kicking, the athletes spend a considerable amount of energy. If there was no

any benefit from keeping the body moving before attacking, then the standing form would be

a good choice, because it can save energy during the competition,

During kicking the muscle activity of the quadriceps was relatively low when comparing the

tensor fasciae latae muscle with the vastus lateralis muscle. This phenomenon may be

explained by the speed of the kicking motion. Since kicking involves a fast knee extension

movement, the recruitment of the quadriceps muscle fibre may reduce. In such case, the

ability to recruit muscle fibre under rapid movement becomes the most important factor

affecting the exercise performance. To increase the exercise performance, the ability to recruit

muscle fibre when moving rapidly should be enhanced. In order to enhance the ability to

recruit muscle fibre during high speed contraction, a high speed isokinetic exercise

programme was designed. The training protocol contained knee concentric extension/flexion

at 240deg/s? 20 repetitions in each set, 5 sets for each session, 3 sessions weekly.

25

The constant preselected velocity during isokinetic movements allows the training to improve

the muscular performance in dynamic conditions (Baltzopoulos and Brodie, 1989). Isokinetic

training at a specific angular velocity increases the maximum torque of the muscle groups

involved at that velocity (Lesmes et al. 1978). Numerous studies have also proved the

training effects of isokinetic exercise (Baltzopoulos, 1989; Perrin, 1989; Perrin, 1993; Ewing,

1990; Johnson, 1976; Lesmes, 1978; Perrine, 1981 and Coyle, 1981). In our study, the speed

of 240 deg/s was chosen as the training velocity.

To increase the muscle strength under high angular velocity, isokinetic exercise training with

a pre-selected speed for the dynamometer seems to be an effective way. In this study, the

isokinetic concentric knee extension peak torque at 240deg/s was significantly increased after

the isokinetic training at that angular velocity. The results show that, in order to increase the

muscle strength in high-speed movement such as Taekwondo kicking, a relatively high

angular velocity in isokinetic training should be selected.

In future, different training programmes could be designed for different muscle groups. The

training exercise may contain isokinetic concentric, eccentric contraction, or isotonic

contraction on specific muscle groups. Feedback from the subjects indicates that hip flexor

and hip adductor seem to be important in Taekwondo kicking. Research work could focus on

these muscle groups to see the possible changes in kicking performance. Moreover,

information about the force applied to the kicking target is very useful for both researchers

and coaches. Finally, a more reliable system should be developed to measure the actual force

during the impact time.

26

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X18423330

HKP 796.815 H77Hong, Youlian, 1946-Biomechanical analysis oftaekwondo kicking technique,performance & training effectsHong Kong : Research Dept,,Hong Kong Sports Development

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