Science & Sports 37 (2022) 51—57
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ORIGINAL ARTICLE
The effects of taekwondo shoes on anterior
cruciate ligament injury risk factors during
jump whip kicks
Les effets des chaussures de taekwondo sur les facteurs de
risque de blessure au ligament croisé antérieur lors des coups
de fouet sautés
B.-O. Lima
, J. Kima
, S.-H. Kima
, J.-H. Chob
, S. Limc,d
,
S.-T. Lime,f,g,∗
a
Department of Physical Education, Chungang University, Seoul, Republic of Korea
b
Department of Sport and Leisure Studies, Shingyeong University, Hwaseong, Republic of Korea
c
Department of Physical Education, Seoul National University, Seoul, Republic of Korea
d
Korea National University of Arts, Seoul, Republic of Korea
e
Olympic Studies Center, Kangwon National University, Gangwon-do, Republic of Korea
f
Waseda Institute for Sport Sciences, Waseda University, Saitama, Japan
g
Nasaret International Hospital, Incheon, Republic of Korea
Received 22 October 2020; accepted 23 April 2021
Available online 20 January 2022
KEYWORDS
Taekwondo shoes;
Anterior cruciate
ligament;
Injury risk factors;
Jump whip kick
Summary
Objectives. — This study aimed to investigate the effect of taekwondo shoes on anterior cruciate
ligament injury risk factors in taekwondo athletes performing jump whip kicks.
Equipment and methods. — The participants comprised 10 taekwondo athletes with no history of
anterior cruciate ligament or lower extremity injuries within the past 12 months. The maximum
hip ﬂexion angle, maximum knee valgus angle, maximum knee extension moment, maximum
knee lateral rotation moment, and quadriceps and hamstring muscle activity ratios were analyzed
using video, ground reaction force, and electromyography analysis systems.
Results. — The maximum knee valgus angle was signiﬁcantly lower when wearing taekwondo
shoes while performing taekwondo jump whip kicks (p = 0.04), and the activity ratio of the
quadriceps and hamstring muscles was low (p = 0.10).
∗ Corresponding author at: 1, Kangwondaehak-gil, Chuncheon-si, 24341 Gangwon-do, Republic of Korea.
E-mail address: limdotor@gmail.com (S.-T. Lim).
https://doi.org/10.1016/j.scispo.2021.04.002
0765-1597/© 2021 Elsevier Masson SAS. All rights reserved.
B.-O. Lim, J. Kim, S.-H. Kim et al.
Conclusion. — Wearing taekwondo shoes had a positive effect on preventing anterior cruciate
ligament injury; therefore, the importance of wearing taekwondo shoes should be communicated
clearly to athletes and coaches to increase their frequency of use and change negative
perceptions regarding taekwondo shoe use during training. Taekwondo competition movements
can cause damage to the anterior cruciate ligament owing to sudden changes in direction and
jump movements. Our results suggest that wearing taekwondo shoes can help prevent anterior
cruciate ligament injuries.
© 2021 Elsevier Masson SAS. All rights reserved.
MOTS CLÉS
Chaussures de
taekwondo ;
Ligament croisé
antérieur ;
Facteurs de risque de
blessure ;
Coup de fouet
Résumé
Objectifs. — Cette étude visait à étudier l’effet des chaussures de taekwondo sur les facteurs
de risque de blessure au ligament croisé antérieur chez les athlètes de taekwondo effectuant
des coups de fouet sautés.
Équipement et méthodes. — Les participants comprenaient 10 athlètes de taekwondo sans
antécédents de ligament croisé antérieur ou de blessures aux membres inférieurs au cours
des 12 derniers mois. L’angle de ﬂexion maximal de la hanche, l’angle maximal de valgus du
genou, le moment maximal d’extension du genou, le moment maximal de rotation latérale du
genou et les rapports d’activité des quadriceps et des ischio-jambiers ont été analysés à l’aide
de systèmes d’analyse vidéo, de force de réaction au sol et d’électromyographie.
Résultats. — L’angle de valgus maximal du genou était signiﬁcativement plus faible lorsque l’on
portait des chaussures de taekwondo tout en exécutant des coups de fouet de taekwondo
(p = 0,04), et le rapport d’activité des quadriceps et des muscles ischio-jambiers était faible
(p = 0,10).
Conclusion. — Le port de chaussures de taekwondo a eu un effet positif sur la prévention des
blessures du ligament croisé antérieur; par conséquent, l’importance du port de chaussures de
taekwondo doit être clairement communiquée aux athlètes et aux entraîneurs pour augmenter
leur fréquence d’utilisation et changer les perceptions négatives de l’utilisation des chaussures
de taekwondo pendant l’entraînement. Les mouvements de compétition de taekwondo peuvent
endommager le ligament croisé antérieur en raison de changements brusques de direction et
de mouvements de saut. Nos résultats suggèrent que les blessures du ligament croisé antérieur
pourraient être évitées en portant des chaussures de taekwondo.
© 2021 Elsevier Masson SAS. Tous droits r´eserv´es.
1. Introduction
Today’s elite sports athletes are excessively focused on
improving performance, with injury prevention being a
lesser priority [1]. Sports injuries reduce athletes’ performances
and have been reported to lead to unstable
psychological conditions, which adversely affect their athletic
lives [2]. In particular, anterior cruciate ligament
injuries can lead to more serious sequelae than other types
of injuries, often resulting in high treatment costs and long
periods of rehabilitation [3].
Approximately 70% of anterior cruciate ligament injuries
are attributed to non-contact injuries involving actions such
as landing after jumping [3,4]. In particular, jump motions
using rotation have a high risk of anterior cruciate ligament
injury as the load transmitted to the knee and the rotational
force act simultaneously upon landing [5]. According to one
study on taekwondo injuries, most anterior cruciate ligament
injuries occur during landing following an aerial kick
[6].
There are several aerial rotation kicks, but the most common
is the jump whip kick. During the jump whip kick action
in taekwondo, damage to the anterior cruciate ligament can
result from an athlete landing on one foot. Andrew et al. [7]
also reported that one-footed landings are associated with
a higher risk of forward cross ligament compared to twofooted
landings. As a result, a one-footed landing carries a
greater risk of injury to the anterior cruciate ligament.
After the adoption of an electronic protection system,
extraneous foot skills were increasingly developed, as seen
at the World Taekwondo Federation General Assembly on
April 5, 2018. To further encourage various eye-catching foot
skills, an additional point was added for the rotating kick
technique, increasing from 1 point to 2 [8]. Without incorporating
a rotating kick in a taekwondo competition, a team
would be less likely to lead the competition.
As the frequency and use of high rotary kicks have
increased during competitions and training, the incidence
of anterior cruciate ligament injuries among taekwondo athletes
has increased as more load is applied to the knee when
landing [9]. Wearing taekwondo shoes may help prevent
injuries during the taekwondo sport; however, studies investigating
how taekwondo shoes prevent injury are limited.
Jin and Kawk [10] reported that assessing simple running
motions was ineffective in evaluating the efﬁcacy of taekwondo
shoes when landing after high kicking.
Early taekwondo shoe manufacture emphasized function
and simple foot protection from external shocks rather
than speciﬁc professional functionality [11]. Athletes and
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Science & Sports 37 (2022) 51—57
coaches seemingly have limited knowledge about the efﬁcacy
of taekwondo shoes, and some athletes still do not
wear taekwondo shoes during training. Taekwondo shoes
have subsequently been developed to enhance exercise
functions and address functional issues such as the prevention
of injuries that may occur during exercise [12].
Some studies have investigated improvements in the shockabsorbing
capabilities of taekwondo shoes in relation to
concerns raised in sports science and sports medicine [12].
Recent trends in the manufacture of taekwondo shoes have
involved designs aiming to prevent anterior cruciate ligament
injuries.
The risk of anterior cruciate ligament injury has been
associated with the maximum hip ﬂexion angle, maximum
knee valgus angle, maximum knee extension moment, maximum
knee lateral rotational moment, and activity ratio
of the quadriceps and hamstring muscles, based on study
ﬁndings by Hewett et al. [3] and Alentorn-Geli et al. [4].
This study aimed to analyze the effects of taekwondo
shoes in preventing anterior cruciate ligament injuries while
performing a jump whip kick action when wearing either two
types of taekwondo shoes, namely, shoes similar to the most
commonly used Nike products or the most recently developed
taekwondo shoes, or when performing the jump whip
kick action while barefoot. This study further aimed to investigate
the efﬁcacy of wearing taekwondo shoes in preventing
anterior cruciate ligament injury among taekwondo athletes
speciﬁcally in relation to the identiﬁed risk factors.
2. Methods
2.1. Participants
Ten males professional taekwondo athletes from the Department
of Taekwondo at our university with >10 years of
taekwondo competition experience participated in this
study. Participants had a mean 13 ± 3 years of athletic
experience, mean age of 24 ± 4 years, mean height of
173.3 ± 8.5 cm, mean weight of 64.2 ± 12.5 kg, and shoe size
ranging from 250—260 mm. Inclusion criteria comprised no
previous history of anterior cruciate ligament injuries and no
history of lower extremity injuries within the last 12 months.
Furthermore, to standardize the athletes in terms of kicking
practice, only participants who were right-foot dominant
were selected. This study was approved by the Chung-Ang
University Institutional Review Board.
2.2. Experimental procedure
Participants received a verbal explanation of the overall
experimental process and precautions, including the purpose
of the experiment and the experimental procedure.
To perform the experiment consistently when performing
barefoot kicks, participants were advised not to kick to the
point where injury to the feet could occur. After providing
informed consent, the participants changed into short
tights, which were part of their experimental clothing. To
adapt to the test site environment, the participants were
familiarized with the location of the test equipment and
provided with precise details concerning the two aerial kicking
motions. Warm-up exercises and a set of two stretching
Figure 1 EMG electrode attachment site.
exercises were then performed to allow the participants
to perform more accurate movements. After demonstrating
the two aerial kicking motions that were to be performed
during the experiment, the participants repeatedly practiced
these kicking motions.
To increase the accuracy of the electromyography (EMG)
data, EMG electrodes were positioned on the participants’
quadriceps and hamstring muscles following hair removal
and skin disinfection using alcohol (Fig. 1).
Before starting the experiment, maximum voluntary
contraction (MVC) measures for the quadriceps and hamstring
muscles were recorded using EMG.
To calculate the values of the kinematic variables that are
risk factors for anterior cruciate ligament injury, reﬂective
markers were attached to major parts of the bodies of the
participants and their taekwondo shoes (Fig. 2).
Static imaging to estimate the human joint center point
was performed for 5 seconds. At this time, the participants
were required to assume an anatomical posture and were
asked to remain motionless. After completing the static
imaging, the participants began the experiment and performed
the jump whip kick motion according to their rhythm
while running in step. Participants performed ﬁve jump whip
kick motions under three different conditions, namely, while
wearing the two different types of taekwondo shoes and
then while barefoot, and random data were collected. Two
taekwondo shoe models were selected comprising a previously
developed early taekwondo shoe model (model A)
and the most recently developed taekwondo shoe model
(model B) (Fig. 3). Model A shoes weighed approximately
180 g based on a 250 mm shoe length, and model B shoes
weighed approximately 200 g (an approximate 20 g weight
difference between the models). Both models were made of
artiﬁcial leather, and the outsole design involved separate
forefoot and rearfoot sections.
All hitting positions were standardized according to the
height of a participant’s face and the hitting position was
ﬁxed by setting a taekwondo mat as the hitting target. We
did not record kicking motions and positions that were not
accurate, or when participants fell on landing. Only motions
that were successfully performed were recorded. Furthermore,
the experiment was stopped any time a participant
asked for a break. To minimize recording deviations due to
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B.-O. Lim, J. Kim, S.-H. Kim et al.
Figure 2 Marker attachment site.
Figure 3 Taeswondo shoes model A (left) and model B (right).
fatigue, the kicking motions were performed after sufﬁcient
rest.
2.3. Data processing
EMG data processing was performed using a wireless EMG
system (Telemyo DTS, Scottsdale, AZ, USA). For row EMG, a
10—350 Hz band pass ﬁlter was used, followed by full wave
rectiﬁcation. Subsequently, a smoothing operation was used
as a root mean square (RMS) of 100 ms, and the measured
EMG values were expressed as ratio values for each motion,
based on the stored MVC measurement values. The activity
ratio of the quadriceps and hamstring muscles was calculated
as follows:
EMG ratio (%) = [quadriceps IEMG/(hamstring
IEMG + quadriceps IEMG)] × 100.
The sampling rate of the infrared camera was set to
200 frames/sec. A non-linear transformation (NLT) technique
was used for the three-dimensional (3D) coordinate
calculation. When 3D coordinate values were calculated,
rectiﬁcation was performed using Butterworth 4th order low
pass ﬁlter cut-off frequency 15 Hz ﬁltering to remove errors
due to noise. The dynamics method was used to calculate
the knee joint moment. This method was applied through
substituting information concerning force and displacement
obtained from the motion analysis with ground reaction
force measurement values in the motion equation. The calculated
moment value was divided by the product of each
participant’s height and weight and standardized and analyzed
to enable relative comparison. To remove noise from
the ground reaction force measurement, a ﬁltering Butterworth
4th order low pass ﬁlter cut-off frequency of 15 Hz
was applied and rectiﬁed [12]. The analysis section was set
from the moment the landing foot touched the ground to
the moment when the knee was maximally ﬂexed.
2.4. Statistical analysis
SPSS 20.0 software was used for statistical analysis. Oneway
repeated analysis of variance tests were conducted to
analyze the effects on the anterior cruciate ligaments of
10 taekwondo athletes in terms of risk factors during jump
whip kicking while barefoot and while wearing model A and
model B taekwondo shoes. The Scheffe method was used
for the post-analysis, and the level for verifying statistical
signiﬁcance was set at a P-value of 0.05.
3. Results
3.1. Maximum hip ﬂexion angle
No statistically signiﬁcant difference was found between
actions performed barefoot and while wearing model A and
model B shoes in terms of the maximum hip ﬂexion angle.
3.2. Maximum knee valgus angle
In terms of the maximum knee valgus angle, there was
a statistically signiﬁcant difference between actions performed
barefoot and while wearing model A and model
B shoes (P < 0.004). Post-hoc analysis results showed that
the maximum knee valgus angle while performing barefoot
was signiﬁcantly greater than when wearing model A shoes
(P = 0.013) and model B shoes (P = 0.012). There was no statistically
signiﬁcant difference between actions performed
wearing either model A or B shoes.
3.3. Maximum knee extension moment
No statistically signiﬁcant difference was found in terms of
the maximum knee extension moment between actions performed
barefoot and when wearing model A and B shoes
54
Science & Sports 37 (2022) 51—57
or between actions performed wearing either model A or B
shoes.
3.4. Maximum knee lateral rotation moment
No statistical difference was found in terms of the maximum
knee lateral rotation moment between actions performed
barefoot and when wearing model A and B shoes or between
actions performed wearing either model A or B shoes.
3.5. Activity ratio of the quadriceps and hamstring
muscles
Concerning the activity ratio of the quadriceps and hamstring
muscles, a statistically signiﬁcant difference was
found between the three levels (P < 0.010). Post-hoc analysis
results showed a signiﬁcantly higher quadriceps and
hamstring muscle activity ratio when barefoot compared to
when wearing model B shoes (P = 0.011). There was no statistically
signiﬁcant difference in the activity ratio between
actions performed barefoot and wearing model A shoes, or
between actions performed wearing either model A or B
shoes (Table 1).
4. Discussion
The angle of hip joint ﬂexion during landing has been
reported to be a risk factor for damage to the anterior cruciate
ligament [13]. As the hip angle increases during landing,
the impact force transmitted to the knee increases [13,14].
Krosshaug et al. [14] reported that if the angle of ﬂexion at
the hip joint increases at the moment of landing following a
jump action, the center of the body moves forward in proportion
to the ﬂexion angle. As the center of the body moves
forward after landing, a greater tension in the anterior cruciate
ligament is generated, which may result in an increased
risk of injury. Boden et al. [13] analyzed videos containing
29 anterior cruciate ligament injuries that occurred during
various sports activities. They found that increased hip
ﬂexion movements were common among injured athletes,
which suggested this was a risk factor for anterior cruciate
ligament injury. In our study, no statistically signiﬁcant
differences were observed in terms of whether the participants
were barefoot or wearing either model A or B shoes
while performing the jump whip kicks. This may have been
because the characteristics of the sport in a taekwondo setting
may have inﬂuenced the outcome. We consider that
coordinated movements of the athlete in trying to quickly
return to the upper body center of gravity occurred because
follow-up movements must be continued immediately after
kicking in an actual competition situation. Further studies
are needed to investigate the movements occurring during a
general drop landing jump motion and a vertical jump task
not only the jump whip kick action performed by participants
in this study.
The maximum knee valgus angle at landing is a known
risk factor for anterior cruciate ligament injury [15,16].
Fukuda et al. [15] reported that as the knee valgus angle
increased, the anterior valgus angle increased, and tension
applied to the anterior cruciate ligament increased owing to
an increase in the tibial push. Hewett et al. [16] reported
that high-difﬁculty motion on the long axis leads to excessive
valgus motion of the knee, which can result in anterior
cruciate ligament rupture. The jump whip kick motion performed
in this study is also a rotational motion occurring on
the long axis and. As it is a motion accompanied by a jump, it
could be seen as a motion with a high probability of anterior
cruciate ligament injury. In our study, statistically signiﬁcant
differences were found in terms of the maximum knee valgus
angle according to whether or not taekwondo shoes were
worn during the jump whip kicks, with actions performed
barefoot showing higher angles than those performed while
wearing model A and model B taekwondo shoes. In a study
that identiﬁed the effects of wearing gymnastic shoes on the
anterior cruciate ligament, the maximum external angle was
reduced by approximately 6 degrees compared with when
gymnastic shoes were not worn [17]. In our study, taekwondo
shoes reduced the angle approximately 4 degrees
compared with the actions performed barefoot. Although
the characteristics of the tasks performed in Lim et al.’s
[17] study and our study were somewhat different, both
gymnastic and taekwondo shoes showed smaller valgus angle
values than barefoot valgus angle values. A decrease in the
maximum valgus angle of the knee joint indicates that the
knee has deviated from its valgus position [17]. When taekwondo
shoes were worn, the smaller valgus angle compared
with barefoot actions was likely because the outsole cushion
on the taekwondo shoes absorbed the ground impact force
when landing, and movement compensating for the impact
force appeared to be small. Jo [18] reported that being barefoot
resulted in a more ﬂexible landing than when wearing
shoes and that, when barefoot, the human body dissipates
the ground reaction force by increasing the knee joint angle.
Park [19] reported that during dance movements, dancing
barefoot resulted in greater impact forces than when wearing
dancing shoes, because of the shock-absorbing capacity
of the dance shoe insole. Based on these two preceding
studies, the reason our barefoot values showed a greater valgus
angle than while wearing two types of taekwondo shoes
was primarily because of a non-shock-absorbing mechanism,
which involves the body’s compensatory action to reduce
the force applied to the knee through increasing the shock
absorption time. Therefore, it is possible that the risk of
damage to the anterior cruciate ligament is further reduced
on the side of the maximum knee valgus angle when wearing
taekwondo shoes as opposed to performing these actions
while barefoot.
The maximum knee extension moment at landing has
been reported to be one of the risk factors for anterior cruciate
ligament injury [3,20]. Yu et al. [20] reported that when
the knee extension moment is increased, the shear force
that causes the tibia to slide forward is also increased. Minimizing
the shearing force is important as the increase in
the tibia’s anterior thrust raises the possibility of anterior
cruciate ligament injury. Hewett et al. [3] reported that an
increase in the knee extension moment increases tension on
the anterior cruciate ligament, thereby raising the risk of
injury. In our study, no statistically signiﬁcant difference was
found in the maximum knee extension moment according to
whether taekwondo shoes were worn during the jump whip
kick actions; however, the numerical values for both models
A and B were smaller than those obtained when performing
55
B.-O. Lim, J. Kim, S.-H. Kim et al.
Table 1 Change in variables.
Barefoot (a) Model A (b) Model B (c) F P Post-hoc
Maximum hip ﬂexion angle (degree) 28.64 ± 6.56 30.85 ± 10.30 32.99 ± 9.40 0.598 0.557
Maximum knee valgus angle (degree) 13.94 ± 2.94 10.21 ± 2.66 10.18 ± 2.14 6.901 0.004 a—b: 0.013
c—a: 0.012
Maximum knee extension moment
(Nm/kg·cm)
1.47 ± 0.15 1.33 ± 0.16 1.30 ± 0.17 2.813 0.078
Maximum knee lateral rotation
moment (Nm/kg·cm)
−1.05 ± 0.17 −0.93 ± 0.15 −0.98 ± 0.13 1.575 0.226
Activity ratio of the quadriceps and
hamstring (%MVIC)
72.64 ± 6.62 65.52 ± 8.77 61.16 ± 7.90 5.493 0.010 a—c: 0.011
barefoot. The extension moment value was calculated based
on the ground reaction force value and the moment arm of
the knee joint, and it had a high correlation with the impact
force. Kaelin et al. [21] reported the effects of outsole shoe
material on impact force during a drop landing motion. They
noted that the impact force generated by the landing motion
of the soft shoe outsole reduced by up to 18%. In contrast,
our study ﬁndings showed no such differences.
The maximum knee lateral rotational moment on landing
has been reported to be a risk factor for anterior cruciate
ligament injury [22]. Berns et al. [22] reported that the
risk of anterior cruciate ligament injury is further increased
when the shear force that causes tibial thrust is transmitted
and lateral rotation is applied to the knee joint.
In particular, the lateral rotational moment generated in
the knee joint is highly correlated with anterior cruciate
ligament injury because considerable anterior cruciate ligament
torsion occurs due to the axial torque when the foot
and knee are ﬁxed to the ground [3,23]. The jump whip
kick is a rotational jump kick based on a vertical axis,
and rotational inertia occurs in the ankle and knee joints
after landing. Accordingly, the tendency of the knee joint to
rotate outward was noteworthy in our participants, and we
hypothesized that taekwondo shoes could be an index used
to determine whether they were effective in controlling
rotation. However, our study ﬁndings indicated no statistically
signiﬁcant difference in the maximum knee lateral
rotational moment either when wearing taekwondo shoes
or not during the jump whip kick action. Park and Lee
[11] reported a signiﬁcant difference while wearing taekwondo
shoes in one part of the rotational traction during the
taekwondo rotation kick motion. Based on previous studies,
we considered that taekwondo shoes would affect rotation;
however, our study ﬁndings did not support this proposition.
We consider that the main reason why the maximum knee
laterals rotational moments in this study did not show any
signiﬁcant difference was due to the varied characteristics
of the kick applied in this experiment, and further research
should be undertaken to assess the relevant factors more
precisely.
The activity ratio of the quadriceps and hamstring muscles
at landing has also been reported to be a risk factor
for anterior cruciate ligament injury [23,24]. Boerboom
et al. [24] proposed that as the quadriceps activity ratio
increases, the hamstring muscles weaken and the probability
of an anterior cruciate ligament injury increases.
Moreover, anterior cruciate ligament injury is prevented
when the quadriceps and hamstring muscles co-contract.
The hamstring muscles function to control excessive movement
of the tibia [25]. The lower the hamstring muscle
activity, the higher the risk of injury as the hamstring
muscles are the only muscles to support anterior cruciate
ligament tension. Therefore, combined quadriceps and
hamstring muscle action prevents excessive anterior tibial
push motion, which can help prevent anterior cruciate ligament
injury. In this study, a signiﬁcant difference was found
between quadriceps and hamstring muscle activity ratios
when participants wore taekwondo shoes during the jump
whip kick motion and when performing this action barefoot
and while wearing model B shoes. Our ﬁndings suggest
that anterior cruciate ligament injury can be better avoided
in terms of this activity ratio when wearing model B shoes
than when performing these actions barefoot. No signiﬁcant
difference was found between quadriceps and hamstring
muscle activity ratios when the jump whip kick motion was
performed barefoot and while wearing model A shoes. However,
the quadriceps muscle activity ratio while barefoot was
higher than that when wearing model A shoes. While wearing
taekwondo shoes, the quadriceps and hamstring muscle
activity ratio decreased, which indicated that the activities
of the quadriceps were lowered. In this study, the barefoot
EMG activity ratio was 72.64; while wearing model A
shoes, the EMG activity ratio was 65.52; and while wearing
model B shoes, the EMG activity ratio was 61.16. At all
three levels, the quadriceps muscles were more active than
the hamstring muscles. However, considering that model
A shoes decreased this activity by approximately 7% compared
to barefoot actions and that model B shoes decreased
this activity by approximately 11% compared to barefoot
actions, it was clear that quadriceps and hamstring muscle
co-contraction improved when wearing taekwondo shoes.
Taekwondo shoes appear to have reduced the activity of
the quadriceps muscles more than when performing barefoot
as taekwondo shoes absorb the impact force and lower
ground reaction forces. Reeves et al. [26] compared and
analyzed muscle activity using muscle taping and reported
that a decrease in soleus muscle activity when taped was
related to ground repulsion when landing after jumping.
Therefore, when considering these previous ﬁndings and the
results of this study, it could be concluded that the activity
of the quadriceps muscles decreased due to lowering of the
ground repulsion resulting from the shock absorption of the
56
Science & Sports 37 (2022) 51—57
taekwondo shoe outsole. It would appear that internal
forces on the taekwondo shoes decreased due to the shockabsorbing
capacities of the shoes. In terms of the activity
ratio, no statistically signiﬁcant differences were found
between actions performed barefoot and when wearing
model A shoes and performing barefoot and wearing model
B shoes. This may have been due to differences in cushion
thickness and materials in the forefoot and hindfoot outsoles
of the taekwondo shoes. In model B shoes, the hindfoot outsole
material was softer with thicker cushioning than that
of model A shoes, and model B shoes could better withstand
impact forces.
5. Conclusion
Wearing taekwondo shoes had a positive effect on preventing
anterior cruciate ligament injury; therefore, the
importance of wearing taekwondo shoes should be clearly
communicated to athletes and coaches to increase their
frequency of use and change negative perceptions regarding
taekwondo shoe use during training. Further studies are
needed to conﬁrm our results through experiments comprising
tasks such as drop landing and vertical jumps that
are more involving than the jump whip kick motion used in
taekwondo competitions.
Disclosure of interest
The authors declare that they have no competing interest.
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