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Development and evaluation of a novel taekwondo chest protector to improve mobility when performing axe kicks



The axe kick, in Olympic style taekwondo, has been identified as the most popular scoring technique aimed to the head during full contact competition. The first purpose of this study was to identify and investigate design issues with the current World Taekwondo Federation approved chest protector. A secondary purpose was to develop a novel chest protector addressing the identified design issues and to conduct a biomechanical analysis. Fifteen male elite Taekwondo players were selected to perform three different styles of the axe kick, i.e., front, in-out, and out-in axe kick five times each for a total of 45 kicks. Two-way repeated measures ANOVA showed significant differences between the novel and existing chest protector conditions for vertical height of the toe, downward kicking foot speed, hip flexion angle and ipsilateral shoulder flexion extension range of motion (ROM) (p < 0.05). There were no significant differences between the control condition (no chest protector) and the novel chest protector condition for these variables (p > 0.05). These results indicate that the novel chest protector interferes less with both the lower and upper limbs during the performance of the axe kick and provides a more natural, free-moving alternative to the current equipment used.
Biology of Sport, Vol. 30 No1, 2013 51
Novel taekwondo chest protector
Reprint request to:
Her Jin Gang
Graduate School of Medical &
Therapy Science, Hallym University
Hallym daehak-gil
200-702 Korea
for publication
According to the World Taekwondo Federation (WTF) there are more
than 80 million [8] practitioners of Taekwondo (TKD) in 200 coun-
tries [14]. The WTF has amended earlier rules [15] to now allow
four points for successful spinning kicks to the head. As a direct
result it has been recently demonstrated, in a study of the techniques
used in the WTF nals from 2001 to 2011, that there has been
an increase in the number of kicks executed by athletes to
the head
[5]. Koh and Cassidy [6], in a study of the incidence of
concussions in TKD competitions, concluded that the most common
head strikes observed in competitions in Korea were the axe kick,
roundhouse kick, back kick and spinning hook kick.
The axe kick has been shown to be a highly effective offensive
and defensive scoring technique [6,11] and its purpose is to attack
an opponent’s head with a powerful downward force [13]. In Koh
and Watkinson’s study [7], from a total sample of 1652 males and
676 females, 51.4% of head blows were by the axe kick, followed
by the roundhouse kick, (25.7%). The sequential movements during
the axe kick include the knee raising in an upward in-to-out or out-
to-in arc motion. Another variation to this kick involves the simple
, Ko J.Y.
, Choi E.Y.
, Her J.G.
, O’Sullivan D.M.
Department of Rehabilitation Therapy, Hallym University, Korea
Department of Rehabilitation Medicine, CHA University, CHA Bundang Medical, Rep. of Korea
Graduate School of Medical & Therapy Science, Hallym University, Korea
College of Sports Science, Chung-Ang University, Korea
ABSTRACT: The axe kick, in Olympic style taekwondo, has been identied as the most popular scoring technique
aimed to the head during full contact competition. The rst purpose of this study was to identify and investigate
design issues with the current World Taekwondo Federation approved chest protector. A secondary purpose was
to develop a novel chest protector addressing the identied design issues and to conduct a biomechanical
analysis. Fifteen male elite Taekwondo players were selected to perform three different styles of the axe kick,
i.e., front, in-out, and out-in axe kick ve times each for a total of 45 kicks. Two-way repeated measures ANOVA
showed signicant differences between the novel and existing chest protector conditions for vertical height of
the toe, downward kicking foot speed, hip exion angle and ipsilateral shoulder exion extension range of
motion (ROM) (p<0.05). There were no signicant differences between the control condition (no chest protector)
and the novel chest protector condition for these variables (p>0.05). These results indicate that the novel chest
protector interferes less with both the lower and upper limbs during the performance of the axe kick and provides
a more natural, free-moving alternative to the current equipment used.
KEY WORDS: axe kick, novel chest protector, taekwondo
raising of the leg straight up and down in front of the body, where
the leg is extended above the target and pulled down onto the tar-
[1]. Because the axe kick motion requires the kicking foot to be
raised higher than the intended target, the angle created at the hip
joint is found to require a substantially large range of motion[11].
Various studies have been carried out about different aspects of
the chest protector in taekwondo, focusing on protective quali-
ties[3,4,9] and the introduction of the electronic scoring protector
system[2]. The rst published study [9] investigated the protective
qualities of the chest protector in taekwondo for various swing-like
kicks and push-like kicks. The authors demonstrated that without
a chest protector, a kick to the chest can induce thoracic deections
up to 5 cm and peak viscous tolerance values of up to 1.4 m · s
This means that if a player is to receive a kick unprotected, there is
a high probability of serious injury. Similarly, there have been two
further studies investigating the protective function of the chest pro-
tector [3,4]. Chi et al. [2] report on the use of wireless force sensing
chest protectors and their role in improving judging in taekwondo
competition. However, there have been no published studies that
Original Paper
Biol. Sport 2013;30:51-55
DOI: 10.5604/20831862.1029822
Woo J.H. et al.
examine the ergonomic difculties of having to wear a chest protec-
tor during competition.
At the 2011 Gyungju World Taekwondo Competition the authors
surveyed the 56 Korean professional players (age: 21.8 ± 2.21 years)
using the provided satisfaction survey of the chest protector (Figure
Over 96% of the players agreed with the statement that the current
chest protector interferes with kicking to the head. When the players
were asked about which kick in particular the chest protector interfered
with, over 91% indicated the axe kick. To investigate whether the
chest protector was really interfering with the performance of the axe
kick the following variables were recorded: maximum vertical height
of the toe, maximum downward kicking foot speed, hip exion (rela-
tive angle between the trunk and the thigh), ipsilateral shoulder
exion-extension range of motion and ipsilateral shoulder extension
pulling speed.
The purpose of this study was to discover functional performance
limitations associated with using the current WTF approved chest
protector and to modify the chest protector to t more ergonomically
to enhance axe kick functional kicking performance. The nal objec-
tive was to evaluate the effect of this modied chest protector on
biomechanical kicking parameters, in comparison to two other kick-
ing conditions: wearing the WTF approved chest protector, and
a control condition (no chest protector).
Development of novel chest protector. Prior to the change in design
of the existing chest protector the authors carried out a survey about
the satisfaction level of the chest protector among the national team
player squad in Korea. Fifty-six of these professional players com-
pleted the questionnaire which included closed and open-ended
questions (Figure 1). When asked if the chest protector interferes
with kicking to the head, over 96% of the players indicated that it
was a limiting factor, and 91% of these respondents indicated that
the axe kick was the most restricted technique. These responses
provided the basis for the follow through study involving the develop-
ment and assessment of the ergonomic ecology of the design.
New Hogu
Ofcial Size 3 3
Recommended Weight Range (kg)
51~63 51~63
A Chest circumference (cm) 98 94
Length from naval to sternum (cm)
47.5 35.9
C Closure length (cm) 29.5 25
D Shoulder width (cm) 15 14
E Centre of side length (cm) 29.5 20.3
Biology of Sport, Vol. 30 No1, 2013
Novel taekwondo chest protector
For sizing of the chest protector, the height, weight, chest circum-
ference, waist front length, front interscye eld length, back interscye
eld length, closure length (iliac crest to scapular inferior angle),
shoulder width, neck-clavicle length (rst rib to inferior part of the
clavicle) and clavicle length of 20 Taekwondo players were measured
using a vernier calipers (NA500-300s, 600s, Bluebird, Korea). The
male (54-62 kg) and female (51-62 kg) players surveyed all used
the ofcially approved size 3. These measurements were performed
both in a standing position and in a standard ghting position. The
measurement changes were based on the measurements shown in
The following changes were applied to the dimensions of the chest
protector as a result of the anthropometric measurements and com-
ments from the survey. The 95th percentile was used for the tting
as the 50th percentile was suggested to be too small [16]. With the
original chest protector 2 cm above the clavicle, the athletes tended
to pull or move the chest protector down approximately 8 cm. This
8 cm was measured between before and after the players adjusted
the chest protector for comfort. As a result of the players moving the
chest protector down, it began to interfere with their kicking and as
they kicked the chest protector would slide back up, hitting their neck.
Therefore to prevent the players from repositioning their chest protec-
tor to a lower position the straight neck part was changed to a V-neck.
During competition, dynamic trunk positions (e.g., trunk exion) force
the clavicle to navel distance to be shortened by 6.0 cm to 35.9 cm.
This altering of the clavicle-navel distance indicates that the chest
protector is too long, thus interfering with the hip range of motion
during various kicking techniques. Side dimensions (C, D and E) were
shortened to allow for more movement of the scapula and more
natural arm movement. The sides were curved to follow more move-
ment for both the legs and the arms accordingly. The lower parts were
shorted to follow the arc above the iliac crest and the higher parts
were shortened to follow the natural curve of the scapula (Figure 4).
In addition, the standard chest protector is made out of 1.0 cm
of polyester sponge and 1.5 cm of ethylene vinyl acetate copolymer
for shock absorption. To increase the pliability and comfort, the pad-
ding was changed to two sheets of memory foam (width = 0.5 cm).
Two sheets of ethylene vinyl acetate copolymer (width = 0.5 cm)
were covered with one sheet of toilon (width = 0.5 cm). A rubber
band was also used to x the chest protector as close as possible to
the body for extra comfort.
Fifteen elite collegiate level taekwondo players (mass 59.4 ± 4.3kg,
height 1.71 ± 0.04 m, leg length 0.84 ± 0.03 m) were recruited.
Each of these elite participants reported over ten years of experience
in taekwondo. Participants suffering from any musculoskeletal injury
within the last two years were excluded.
Experimental procedure
Participants completed an informed consent form approved by the
Hallym University Institutional Review Board held in accordance with
the Declaration of Helsinki. After completion of the informed consent
form, subjects were instructed to warm up by performing a combina-
tion of ten jumping jacks and light static stretching of the following
muscles: quadriceps, biceps femoris, soleus, gastrocnemius, external
abdominal obliques, erector spinae. In total the warm-up took ap-
proximately 10 minutes. After this warm-up, reective markers were
xed to the relevant landmarks via double sided tape. Each of the
participants was instructed to perform each kick ve times for each
condition. Each player executed a total of 45 kicks, 15 kicks for each
condition, 5 in-out axe kicks, 5 out-in axe kicks and 5 straight axe
kicks for each of the chest protector conditions. Conditions consisted
of wearing the standard WTF approved chest protector, our novel
chest protector, and the control condition (no chest protector). All
kicks and chest protector conditions were randomized prior to testing
and subjects were unaware of the order until execution of each kick
and introduction of each condition. For each of the conditions max-
imum vertical height of the toe, maximum downward kicking foot
speed, hip exion (relative angle between the trunk and the thigh),
ipsilateral shoulder exion-extension range of motion and ipsilateral
shoulder extension pulling speed were measured.
Data collection and statistical analysis
Kinematic data were recorded by eight Qualisys cameras (OQUS
100, Sweden) at a frequency of 150 Hz. Cameras were synchronized
and reective markers were manually labelled using QTM (Qualisys
Track Manager, Sweden). All data were exported as a C3D le and
processed and ltered by a second order Butterworth lter at 15 Hz
using Visual3D version 4.01 (C-motion, Germantown, MD, USA).
Repeated measures ANOVA was used to detect differences between
the three conditions and independent variables. The level of signi-
cance was set at 0.05.
1) Chest protector is the standard protective chest guard which must
be worn by all athletes that are participating in Olympic style TKD
competitions sanctioned by the WTF.
Woo J.H. et al.
2) Leg length is measured from the marker on the anterior superior
inferior spine (ASIS) to the marker on the medial malleolus.
3) Vertical height of the toe is measured by the maximum height in
the z-axis from the positional data of the reexive marker on the
kicking foot’s head of the fth metatarsal.
4) Downward kicking foot speed is measured from the speed of the
marker on the fth metatarsal in the downward direction, i.e. after
the foot has reached its maximum height to impact.
5) Hip exion is the relative angle measured between the thigh seg-
ment and the trunk segment.
6) Ipsilateral shoulder exion-extension range of motion is measured
during the axe kick from the point of maximum exion of the upper
arm to the maximum extension of the upper arm.
7) Ipsilateral shoulder extension pulling speed is the measured speed
at the distal end speed of the upper arm segment.
Table 2 displays the descriptive statistics and results of the two-way
3 (chest protector condition) x 3 (kick type) repeated measures
ANOVA performed on the variables. There were no signicant inter-
actions between the kick type and the chest protector condition.
There were signicant main effects (p<0.05; refer to Table 2) re-
corded between the chest protector conditions for all variables except
the ipsilateral shoulder extension pulling speed for the straight axe
kick. Post hoc analyses using the Bonferroni post hoc criterion were
used to show signicant differences within the groups. Results of the
post-hoc analyses are also included in Table 2.
The purpose of this study was to compare the effects of a modied
chest protector and those of a standard chest protector on axe kick
performance. Results of the Korean Taekwondo National Team
players’ responses to the survey indicated that existing chest pro-
tectors interfere with performance of the axe kick. Based on these
results of the satisfaction survey, the chest protector was redesigned
to be more exible and not to interfere with kicks aimed to the
head. The main changes to the chest protector included the change
of padding material and layering to improve pliability and to narrow
the side protection as it restricted thigh and upper arm movements.
The effects of these modications on vertical height of the kicking
toe, downward kicking foot speed, hip exion, ipsilateral shoulder
exion-extension ROM, and ipsilateral shoulder extension pulling
CP types Height (m) Foot speed (
m · s
) Hip exion (°) Shoulder ROM (°)
Shoulder speed (m · s
Front axe kick
1.76 ± 0.05
7.91 ± 1.10
146.98 ± 34.50
71.83 ± 16.18
2.70 ± 0.78
1.72 ± 0.05
7.22 ± 0.83
140.01 ± 32.52
60.45 ± 21.16
2.35 ± 0.40
1.75 ± 0.05
7.84 ± 0.98
145.11 ± 32.91
69.67 ± 22.54
2.63 ± 0.51
p <0.001 <0.001 0.003 0.010 0.080
F 10.417 17.818 7.413 5.512 3.082
effect size 0.427 0.733 0.346 0.282 -
In-out axe kick
1.74 ± 0.05
7.72 ± 0.57
150.95 ± 34.50
71.45 ± 16.22
3.00 ± 0.83
1.69 ± 0.06
7.24 ± 0.69
140.12 ± 33.11
63.24 ± 15.81
2.57 ± 0.57
1.73 ± 0.05
7.70 ± 0.84
146.81 ± 32.28
69.36 ± 19.69
2.94 ± 0.65
p <0.001 <0.001 <0.001 0.014 0.010
F 36.220 17.546 15.298 5.022 6.715
effect size 0.721 0.556 0.522 0.264 0.508
Out-in axe kick
1.72 ± 0.05
7.41 ± 0.73
145.55 ± 32.40
68.93 ± 23.95
2.93 ± 0.56
1.69 ± 0.06
6.87 ± 0.58
135.75 ± 33.67
57.75 ± 25.30
2.44 ± 0.40
1.71 ± 0.05
7.34 ± 0.74
143.94 ± 32.02
68.39 ± 24.10
2.87 ± 0.51
p <0.001 <0.001 0.003 <0.001 0.006
F 12.270 13.460 9.765 12.189 7.891
effect size 0.467 0.490 0.600 0.465 0.548
Note: CP = chest protector; CP
= no chest protector; CP
= existing chest protector; CP
= novel chest protector;
Height = maximum vertical height of the toe; Foot speed = maximum downward kicking foot speed; Shoulder ROM = ipsilateral shoulder exion-
extension range of motion; Shoulder speed = ipsilateral shoulder extension pulling speed.
1 signicantly different compared with CP
2 signicantly different compared with CP
3 signicantly different compared with CP
Biology of Sport, Vol. 30 No1, 2013
Novel taekwondo chest protector
speed, compared to the standard WTF approved chest protector
and the control condition, were analyzed. The downward kicking
foot speed of the straight axe kick before impact for the control
group, the WTF approved protector group, and the novel chest
protector group was 7.91 ± 1.10
m · s
, 7.22 ± 0.83
m · s
, and
7.84 ± 0.98
m · s
, respectively. The maximum value recorded by
this study was 11.43
m · s
, which was nearly identical to the back
leg axe kick foot velocity (11.3
m · s
) recorded by Sung and col-
leagues [10].
With the importance of the use of the rectus abdominal muscles
and hip exors to raise the kicking leg, the chest protector must be
exible and not restrict hip exion. The kicking foot height was high-
est for the no chest protector condition (1.76 ± 0.05 m) followed
by the novel chest protector (1.75 ± 0.05 m) then the existing chest
protector (1.72 ± 0.05 m), which implied that the existing chest
protector interfered with the hip exion during the kick. There was
a signicant difference in the foot height between the no chest pro-
tector group and the existing chest protector group. However, there
was no signicant difference between the no chest protector group
and the novel chest protector group.
The same order was shown for both the in-to-out axe kick and
the out-to-in axe kick. With the extra height the player had the op-
portunity to develop more downward foot speed. The results showed
signicant differences between the no chest gear condition and the
existing chest protector condition. The results also showed no sig-
nicant differences between the no chest protector condition and the
novel chest protector. Tsai and his colleagues examined how the
upper arm motion affects the lower limb motion while performing
the spinning heel kick [12]. Their data illustrated that the larger
range of motion in the upper limbs, mainly the upper arm, then
the larger the range of motion in the lower limbs. In this study, ipsi-
lateral shoulder range of motion was calculated to observe whether
the chest protector had any effect on the movement of the upper
arm. Similarly, ipsilateral shoulder extension pulling speed was cal-
culated for the same purpose. Our data suggest that even though
the range of motion is larger for the upper arm movement, there were
no signicant differences between the groups in pulling arm speed.
One of the limitations of this study is that the safety performance of
the chest protector was not tested. The authors intend to test the
shock absorption of the chest protector in a future study. It is also
intended to develop more sizes and survey the appropriateness of t
and comfort.
The ndings of this study, shown by the biomechanical variables,
such as kick height, foot speed, hip exion, shoulder ROM and
shoulder speed, illustrate that using the novel chest protector
enables a player to have more natural axe kicking motion.
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... In recent years, World Taekwondo incorporated modern technology into the discipline, i.e., the Protector Scoring System (PSS), the instant Video Replay System (VRS), and relevant competition rule changes [12][13][14][15][16]. The latest revisions in Olympic taekwondo rules penalize non-fighting actions, the presence of "phantom striking", and unnecessary leg elevation; limit possible fouls; and modify the scoring system. ...
Full-text available
We aimed to compare the change in exercise response to taekwondo-specific circuit workouts before and after competition rule amendments. A total of 240 workouts in 15 elite athletes were analyzed over two years. Physiological and kinematic data were gathered with the wireless Bioharness system along with capillary blood samples for lactate concentration. Progressive exercise tests until exhaustion were periodically performed to obtain reference data. The rule changes resulted in significant increases (mainly medium or large effects) in the physiological (2.9-14.4%) and kinematic (4.8-10.1%) response to taekwondo-specific workouts. The largest increases were for peak breathing rate (12.0%), energy expenditure (6.6%), blood lactate immediately after exercise (10.2%) and at the 30th min of recovery (14.4%), and peak kinematic activity (10.1%). Significant differences between taekwondo-specific workouts and tournament combats persisted after the shift from old to new rules, ranging from 2.4 to 38.5% for physiological and from 2.9 to 15.5% for kinematic variables. The largest workout-combat differences were revealed for post-exercise (15.9%) and recovery (38.5%) blood lactate, peak (-15.8%) and relative (-15.0%) breathing rate, and mechanical (13.5%) and physiological (14.2%) intensity. Our study suggests that the rule amendments significantly modify the exercise response to discipline-specific workouts and that taekwondo-specific training sessions do not fully recreate the tournament demands in terms of physiological and kinematic load.
... Taekwondo is a globally known martial arts sport with practitioners in more than 206 countries. A Taekwondo player is required to have highly demanding physical and technical abilities to effectively perform a series of fast attack and counterattack actions against an opponent within a few seconds [5][6][7]. The subjective nature of the scoring system in Taekwondo competitions has been criticized and is often the subject of disputes and protests among coaches and players inside and/or outside the competition venue. ...
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The purpose of this study was to compare the patterns of skill actions executed during Taekwondo competitions when wearing and not wearing an electronic protector. To achieve this purpose, 110 matches from two university-level Taekwondo championships were taped and analyzed. The performance skills were composed of 18 detailed skills and grouped into five categories by considering kicks to the target area (chest or head/face). The data were organized in the form of a contingency table that demonstrated the relationship between grouping factors (skills, protectors, win–lose, and weight division). A log-linear analysis was carried out to investigate the effect of the grouping factors (IVs) on the skills (DV) using SPSS Statistics. The results obtained in the present study can be summarized as follows. First, the overall proportion of “points” called by the judge for the general protector (32.3%) was approximately 3.4 times that for the electronic protector (9.5%). Second, for the electronic protector, the proportions of kicks to the chest area were in the following order: Roundhouse kick (R-Kick) (44.7%), Pushing kick (P-kick) (19.3%), Turn kick (T-kick) (8.7%), and Double roundhouse kick (DR-kick) (7.6%). For the general protector, the order differed slightly, with T-kick and P-kick switched around with different proportions. Third, the proportion of kicks to the head/face was higher for the electronic protector (19.8%) than for the general protector (10.4%), and this difference was even more distinct when the light (−68kg) (33.5% (electronic) vs. 6.5% (general)) and heavy (+85kg) (1.4% (electronic) vs. 13.3% (general)) weight divisions were compared. Finally, the match status (win/lose) had no significant effect on the pattern of playing actions for both the protectors. The result from this study suggests that skill frequency of linear simple movement for activating electrical protector’s sensor is increased, while the one of rotational complex movement is decreased gradually. Additionally, headgear without sensors, such as for a hit movement to the face/head part, represent characteristics of increased attack skills to the facial area; these scores are provided through subjective judgement, and consequently changes in performance skills can occur.
... On the contrary, our tests showed that the cheaper K ® brand performed better than brands D ® and A ® . Along with the existing approval standards which stipulate the need to reduce the impact force below the 2000 N threshold, and the use of ethylene vinyl acetate, nitrile rubber or polyurethane only materials (Ramazanoglu, 2012;Woo et al., 2013); the superior performance of brand K ® indicates that further standards are required. ...
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The objective of the study was to evaluate and compare different brands of forearm, shin, hand and foot protective equipment used in Taekwondo. The most popular brands of large forearm, shin, hand and foot protectors (D®, A®, K ®), approved by the World Taekwondo and Korean Taekwondo Association, were examined. A drop test was used to test the protective equipment using impact levels of 3J, 9J, 12J and 15J for the forearm and shin guards, and 3J and 9J for the hand and foot protectors. The protective equipment was hit ten times from each of the designated drop heights. The drop test is described in the European standards manual of protective equipment for martial arts (SRPS EN 13277-2). The maximum force (MF) and impulse were lowest for brand K® (2610.3 ± 1474.1 N), and brand A® (9.6 ± 3.1 Ns), respectively, for the forearm guards; for brand A® (2053.4 ± 1267.1 N) and brand K® (9.8 ± 3.5 Ns), respectively, for the shin guards; for brand K® (4486.5 ± 1718.4 N), and brand A® (6.3 ± 1.1 Ns), respectively for the hand protectors; and for brand A® (3733.7 ± 2465.3 N), and brand D® (6.8 ± 0.6 Ns), respectively, for the foot protectors. For the forearm guard brand and impact level, there was a significant interaction effect for the MF (F=42.44, η2=.677, p <0.001) and impulse (F = 33.97, η2 = 0.626, p <0.001). Based on the MF, brand K® performed the best for the forearm guards and hand protectors, and brand A®, for the shin guards and foot protectors. The best results for the impulse were for brand A® (forearm guards and hand protectors), brand K® (shin guards) and brand D® (foot protectors).
... Note: % with respect to the total number of taekwondo papers published (n = 176). The international relevance of taekwondo, supported by its Olympic status, has triggered the development of its technical [Moenig 2011; Moenig, Cho, Song 2012] and tactical characteristics, [Kwok 2012; Menescardi Royuela, Bermenjo, Herrero et al. 2012] , its competition rules and technology [Del Vecchio, Franchini, Del Vecchio et al. 2011; Moenig et al. 2012; O'Sullivan, Fife, Pieter et al. 2013; Ramazanoglu 2012; Woo, Ko, Choi et al. 2013]. as well as the interest of coaches and scholars in describing and improving the performances of taekwondo athletes [Bercades and Pieter 2007; Bouhlel, Jouini, Gmada et al. 2006; Bridge, Jones, Hitchen et al. 2007; Butios, Tasika 2007; Casolino, Lupo, Cortis et al. 2012; Chiodo, Flotti, Davalli 2010; Estevan, Álvarez, Falcó et al. 2014; Haddad, Chaouachi, Wong et al. 2011; Markovic, Vucetic, Cardinale 2008; Pieter 2010; Pieter, Heijmans 2007]. ...
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Aim. The aim of the present study was to provide an overview of the scientific literature on taekwondo indexed in the Web of Science main databases (SCI-Expanded, SSCI and A&HCI) until 2013. Method. For that purpose, a bibliometric analysis focused on the distribution of articles per year, research areas, authors, countries represented and journals was performed. One-hundred-seventy-six articles were retrieved from 1989 to 2013, with an increase from 2009 onwards. Results. Among the 38 research areas observed, Sport Sciences accounted the highest percentage (57.4%), whereas Pieter resulted the most represented author (i.e., 15 contributions). South Korea, the USA and Turkey produced the 45.5% of the retrieved papers, whereas the Journal of Strength and Conditioning Research resulted the journal which published the majority of taekwondo articles (i.e., 5.6%). Conclusions. An overview on how the inclusion of taekwondo within the Olympic programme, the development of the Sport Sciences field, and the increase of the Web of Science master journal list could explain the important rise of the scientific production on taekwondo was provided. Despite the considerable amount of research areas, authors, countries and journals involved in taekwondo research, there is a scarcity of scholars developing a continuous and solid research on this martial art.
Objective: This study aims to compare and analyze the difference of impact force attenuation according to size and impact location on a Taekwondo body protector. Methods: Body protectors sized 1 to 5, were impact tested by equipment based on the specifications in the European standard manual (EN 13277-1, 3). The impactor release heights were set to match impact energies of 3 and 15 J. The impactor was made from a 2.5 kg cylindrically cut piece of aluminum. Each body protector was impacted 10 times at the two impact energies and two locations. The differences in performance for each body protector size were compared using a two-way analysis of variance with a significance level of p< 005. The effect sizes were investigated using a partial eta squared value (η2). Results: The significant mean differences between the body protector size and impact area (p< 005) and the average impact time of impact strengths 3 and 15 J were 0.0017 and 0.0012 s, respectively In addition, when an impact strength of 15 J was applied, the maximum resulting impact force exceeded 2000 N for both locations on all sizes. Furthermore, at an impact strength of 3 J size 3 significantly reduced the impact force more than the other sizes; however, size 1 showed the greatest shock absorption at an impact of 15 J. Conclusion: The results of this study show that the shock absorption of body protectors does not increase according to size; i.e., a larger body protector does not reduce the impact load more effectively. To improve safety performance, we recommend a maximum impact force of 2000 N or less for all body protectors.
Conference Paper
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The purpose of the study was to analyze the biomechanics of taekwondo front-leg axe­ kick. One force plates, two synchronized high-speed cameras were used to measure biomechanical parameters in each phase of the front-leg axe-kick. The results included: 1. The average reaction time and movement time were 0.423 sand 0.327 s, which respectively occupied about 56% and 44% of attack time. 2. The maximum velocity of hip, knee and ankle were 1.74 m/s, 5.25 m/s and 7.43 m/s respectively. When the kicking leg touched the target, the velocity of knee and ankle were 0.78m/s, 1.72m1s, and 4.64m1s respectively. 3. The peak vertical GRF and impulse were 0.96 SW and 77.57N-s. For decreasing the movement time, it's suggested that an athlete should increase the power and flexibility of lower extremities during the training section. KEY WORDS: taekwondo, axe-kick, biomechanic INTRODUCTION: Taekwondo is a competitive sport in martial arts. The kicking leg, the unique feature to Taekwondo, is the major attack weapon in Ihe competition (Hon, 1997). Previous studies (Kim, 1'988; Chein, 1991; Tsai, 1998) showed that axe-kick was one of the main offensive actions with high percentage of offense, scoring and success during competition. Axe-kick is the main method of face kick, and which can be divided into front-leg axe-kick and back-leg axe-kick. The purpose of the kick is to attack opponent's head and genetrate a powerful and downward force. Recently study (Chen, Chin & Shiang, 2004)
Conference Paper
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The purpose of this study was to analyze the kinetics of taekwondo axe kick. Twenty junior high school level taekwondo athletes served as subjects, and their mean age, height, weight and training experience were 17.1 ± 1 years, 168.8 ± 5.8 cm, 59.9 ± 6.7 kg and 5.8 ± 1.6 years respectively. Two Kistler force plates and multifunctional record instruments were used to measure kinetic parameters in each phase of the axe-kick motion. The conclusions described as following: 1. the time to peak anterior-posterior ground reaction force of kicking leg prior to the time to peak vertical force. 2.the peak vertical ground reaction force and impulse of support leg were 1.79 times of body weight and 88.1 N-s during leg-lift phase, and 0.86 times of body weight and 64.9 N-s during leg-axe phase. 3. It's suggested that during the training should emphasize to decrease the response time in order to reduce the total time. INTRODUCTION: Taekwondo is a competitive game in martial arts, and the kicking leg is the main attack weapon in competition, which is the unique feature to taekwondo (Hon, 1997). Furthermore, it has defined as an official competitive event in the 2000 Sydney Olympic Game. Generally, the emphasis of timing and power in kicking has been addressed. The more velocities and powers of the action, the more advantages of timing and effectiveness can be gained. Although the ground reaction force (GRF) and impulse in kicking could influence the power of action, but there were few information about that. Axe kick is one kind of kicking style in taekwondo (Kim, 1988; Lee, 1992; Chien, 1991; Tsai,1998). The purpose of the kick is to attack opponent's head, and give it a powerful and downward force. To our knowledge, this type of kick has not been analyzed hitherto by GRF. Previous studies have dealt with punt-style kicking or high front kick in martial art. In these types of kicks, the direction of force on target is the same, and give target an upward force. Furthermore, in addition to the kicking-style analyzed in previous kicking studies, the present study used two force plates under two feet to assess temporal ground reaction force and relative kinetic measurement. In summary, the aim of this study was to investigate the movement time and GRF of kicking leg and supporting leg. METHODS: Twenty skilled taekwondo male athletes of senior high school (their mean age, height, weight and trained experience were 17.1 years, 168.8 cm, 59.9 Kg and 6.6 years respectively) served as subject for this study, and all the subjects provided informed consent to participate. Execution of the motion axe kick analyzed in present study start from a normal standing position (kicking leg behind the support leg) with both feet on two separated force plates. Each subject initiated to response while seeing the light signal. The stick figure sequence of kick leg is shown in Figure 1. The ankle joint of kicking leg is kept fully extension in order to attack the target with the sole of the foot. During the kick, the supporting leg remains almost stationary on the force plate. The kick is performed almost without body rotation. Each subject performed three maximum-effort axe kicks aimed at a practice-used target held to chin level by experiment assistant. The fastest kick from each subject was selected for further analysis. The temporal GRF were simultaneously measured with two force plates (Kistler, 600 Hz).
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The purpose of the research was to study the repeatability of electromyographic (EMG) waveforms of major lower limb muscles during the naeryo chagi (axe kick) in taekwondo. Six male and female athletes, aged between 20 and 24 years served as volunteers. All participants were black belt holders and performed the naeryo chagi with their right leg. The electromyographic activity of rectus femoris, biceps femoris, gastrocnemius lateralis and tibialis anterior was recorded during the kick through four preamplified surface electrodes. The participants preformed 10 successive kicks to a fixed target with 1 min intertrial interval. The electromyograms were recorded during each kick at a sampling frequency of 1000Hz. After the processing of the raw EMG data, myoelectrical activity was normalized on the time and amplitude domain. The coefficient of variation (CV), intra-class correlation coefficient (ICC) and coefficient of multiple correlation (CMC) were computed to test the repeatability of the electromyographic waveforms in each participant. The electromyographic activity during the naeryo chagi demonstrated poor repeatability. More specifically, all CVs were greater than 80%, all CMCs were lower than 0.75 and the majority of the average measure ICCs as well as all single measure ICCs were lower than 0.55. It seemed that only ensemble averages of EMG waveforms obtained from more than ten kicks may be considered as representatives of the muscle function in naeryo chagi and conclusions that have been drawn from a single trial should be reconsidered.
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THE OBJECTIVES OF THIS STUDY INCLUDE: (1) Determination of the attenuation of strike acceleration that Tae Kwon Do sparring safety pads provide from kicks from Olympic style TKD fighters, (2) The sex and weight differentiation in acceleration achieved within the thorax model with the roundhouse kicks. This prospective, observational study utilized 15 Olympic style fighters from an "elite" team kicking a water core heavy bag thorax model with roundhouse kicks. The model was fitted with a tri-axial accelerometer (GCDC, model X250-2) to measure g acceleration from strikes to the bag. The bag was kicked in three, 10 kick phases by all subjects: kicks without padding; kicks with hogu on heavy bag, and kicks with hogu and instep guards on feet. The g acceleration readings were recorded in all phases. Kolmogorov-Smirnov failed for all variables. There were 8 female subjects: median age 14 years, median weight 53.4 kg and 7 male subjects: median age 17 years, median weight 70.45 kg. The ANOVA on ranks of the acceleration from kicks against the bag achieved significance, P=0.001. Spearman rank order correlation between the weights of players and acceleration of strike against the hogu without and with insteps pads was significant, P=0.035/r=0.54 and P=0.018/r=0.59, respectively. Heavier and male subjects tend to produce more force in strikes. Protective chest guard reduces acceleration to the thorax model, but the utility of instep guards is questionable.
Conference Paper
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Ubiquitous and Wearable Computing both have the goal of pushing the computer into the background, supporting all kinds of human activities. Application areas include areas such as everyday environments (e.g. clothing, home, office), promoting new forms of creative learning via physical/virtual objects, and new tools for interactive design. In this paper, we thrust ubiquitous computing into the extremely hostile environment of the sparring ring of a martial art competition. Our system uses piezoelectric force sensors that transmit signals wirelessly to enable the detection of when a significant impact has been delivered to a competitor's body. The objective is to support the judges in scoring the sparring matches accurately, while preserving the goal of merging and blending into the background of the activity. The system therefore must take into account of the rules of the game, be responsive in real-time asynchronously, and often cope with untrained operators of the system. We present a pilot study of the finished prototype and detail our experience.
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Objective: Although some scientific information on electronic body protectors in taekwondo is available, no research has been done to assess the impact of kicks in a competitive situation. The purpose of this study, then, was to assess the energy absorbed by these protectors from kicks performed in an actual taekwondo competition. Methods: Subjects consisted of junior (14-17 years) and senior (≥18 years) male taekwondo-in, who participated in an open tournament. Data on the energy imparted by valid kicks in Joules (J) were collected from a public visual electronic monitor. Results: Energy was higher for the seniors: 264.31 ± 56.63 J versus 224.38 ± 48.23 J for the juniors (eta2 = 0.121). The seniors scored lower in percent impact but the effect was trivial: 123.46 ± 24.77% versus 136.70 ± 26.33%(eta2 = 0.087). Conclusions: The difference between senior and junior taekwondo-in in absolute energy generated was small, while the difference in relative energy impact was trivial in favour of the junior taekwondo athletes.
Background. Limited research has been done on head blows that may result in mild traumatic brain injury in Taekwondo. The purpose of this study was to investigate the fighting conditions under which blows to the head commonly take place, with a view to determining the typical conditions under which injury may occur. Methods. Experimental design: videotape analysis (retrospective). Setting: the semi-final and final matches (a total of 48 matches) at the 14(th) World Taekwondo Championships in 1999. Participants: 64 athletes (32 females and 32 males) who won elimination-round matches (out of 563 competitors), aged 15 to 38 years. Measures: frequency, mechanism of head blows, characteristics of situations leading up to and following head blows, frequency of multiple impacts. Results. A total of 35 incidents of head blow occurred (365 blows per 1,000 athlete exposures). All of these head blows were associated with a direct head or face contact and frequently involved: a closed sparring stance, shorter athletes, axe or roundhouse type kicks, attacker's offensive kick, and head-blow-receiver's offensive action with absence of a blocking skill. Conclusions. To prevent possible brain injury resulting from direct head blows, updated safety education, a complete understanding of concussion for athletes, coaches, and referees, and a rule change in competition Taekwondo are recommended.
This research was to develop Taekwondo trunk protector(Hogu) and head protector's sizing systems corresponding the regulations by World Taekwondo Association. These sizing systems were established using 2003-2004 Size Korea anthropometric data. The result can be summarized as follows: According to the analysis of correlation, most measurements had high relationship with weight for Hogu and head girth for head protector. Six sizes(47, 54, 59, 64, 70, 76) for Hogu and 4 sizes(52, 54, 56, 60) for head protector were suggested in this study. Hogu sizes indicate body weights and head protector sizes express head girth measurements. By the comparison between current Hogu sizes and new sizes, the smaller sizes of new Hogu were bigger than current sizes in bust girth, back fastening length, shoulder length. On the other hand, the bigger sizes of new Hogu were larger than current sizes in bust girth, back fastening length, shoulder length. In addition, new Hogu's lengths were shorter than current Hogu in all sizes. The lengths of Neck to collar bone in new Hogu sizes were longer than current Hogu. In case of the head protector, there were no measurements besides outer circumference of helmet in recognized specifications of WTF. Therefore some referable measurements such as head girth, head length, bitragion arc, sagital arc were suggested in new size specification. When helmet sizes were suggested, the thickness of the NBR foam also were considered.
A major concern in competition taekwondo is the injury potential posed by many of the powerful kicks used. An investigation of the kinetics of four kicks frequently used in competition was performed with high speed video. Velocities were measured, and energy was calculated. Typical values for basic swing kicks were 15 ms-1 and 200 J. Basic thrust kicks possessed 45% less velocity but 28% more energy than swing kicks. Linkage models were developed to simulate the motion and kinetics of the kicking leg. Injury potential was evaluated through thoracic compression and viscous criterion models. These models predict a significant probability of serious injury with all kicks, with thoracic deflections from 3 to 5 cm and peak viscous tolerance values from 0.9-1.4 ms-1, when no protective body equipment is used.