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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.
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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