BIOMECHANICAL CLASSIFICATION OF TAEKWONDO KICKS
Young-Kwan Kim and Richard N. Hinrichs
Arizona State University, Tempe, AZ, USA
E-mail: Young-Kwan.Kim@asu.edu
INTRODUCTION
Taekwondo is one of the martial arts and is
so popular that it has been an official
Olympic event from the 2000 Olympics in
Sydney. The popularity of Taekwondo
mainly comes from its dynamic kicks during
sparring. There are many kinds of kicking
techniques in Taekwondo, such as front kick,
roundhouse kick, side kick, back kick, swing
kick, hook kick, back spinning hook kick,
and axe kick, depending on the plane of
movement and joint action of lower
extremities.
Figure 1: Graphical representation of three style
kicks in Taekwondo.
There are a few biomechanical studies on
front kick and roundhouse kick but the other
styles of kicking have not been studied so
far (Sorensen et al., 1996). The main goal of
kicking is to hit a target correctly with
decent power for getting points in sparring.
Therefore, the fast and forceful kick is very
important to reach high power of kicking.
Even though there are various kicking
techniques in Taekwondo, it is hypothesized
that there are three distinctive styles of
kicking depending on kinematic
characteristics of kicking (see Figure 1). The
swing kick is used to maximize the speed of
the foot at impact. The thrust kick is used to
generate large forces at impact. The
combined kick is used to generate both a
large speed and large forces.
The purpose of this study was to collect
kinematic data of six different techniques of
Taekwondo kick and to classify their
patterns of kicks into three groups
depending on their kinematic characteristics.
METHODSFront Kick (Swing Kick)
Six subjects were recruited from the ASU
Taekwondo club and off-campus
Taekwondo schools. They had a minimum
of three years of Taekwondo training and
participated in practice on a regular basis.Side Kick (Thrust Kick)
Eighteen reflective markers were placed on
the body segments and 10 CCD cameras
(Motion Analysis System, Santa Rosa, CA,
USA) with sampling rate of 200 Hz were
used to record body marker position data.Hook kick (Combined kick)
Subjects were asked to execute randomly
ordered six different kicks in the air and five
trials for each kick. The six kicks were front
kick (FR), roundhouse kick (RH), side kick
(SD), back kick (BA), hook kick (HO), and
back hook kick (BH).
Saved body position data were used for
kinematic data analysis and pattern analysis
following 2nd
order zero-lag Butterworth
filter (cutoff frequency 10 Hz). Repeated
measures ANOVA on the maximum kicking
speed of each kick were performed. Angleangle
plot for hip and knee flexion/extension
angles were investigated.
RESULTS AND DISCUSSION
Roundhouse kick (RH) showed significantly
higher speed (13.9  0.72 m/s) than SD, BA,
and HO. Side kick (SD) speed (8.55  0.53
m/s) was significantly lower than FR and
RH (see Figure 2).
0
4
8
12
16
20
FR RH SD BA HO BH
Maxkickingspeed(m/s)
Swing Kick
Thrust Kick
Combined
Kick
Figure 2: Swing kicks generally showed the highest
kick speeds while the thrust kicks generally showed
the lowest kick speeds.
FR
Knee
Hip
60 180
60
180
Knee
Hip
RH
60 180
60
180
Knee
Hip
SD
60 180
60
180
Knee
Hip
BA
60 180
60
180
Knee
Hip
HO
60 180
60
180
Knee
BH
Hip
60 180
60
180
Figure 3: Angle-angle plot (hip-knee) indicates the
complexity of the combined kick.
Overall mean of combined kick was
between swing kick and thrust kick.
The angle-angle plot (hip flexion/extensionknee
flexion/extension) showed the
qualitative pattern of each kick and the
complexity of movement of the kicking leg
(see Figure 3). RH showed the consistency
across individuals. Combined kick (HO and
BH) indicated the complexity of joint
movement.
SUMMARY/CONCLUSIONS
This study indicates that swing kicks (FR
and RH) generally achieve the highest
kicking speeds of all the types of
Taekwondo kicks. The swing kicks use the
open kinetic chain principle in an attempt to
maximize the distal end linear velocity
(Putnam, 1991). Hence, they have a velocity
advantage in reaching high mechanical
power. Thrust kicks (SD and BH) are
performed by opposite torque directions
between hip and knee joints to thrust the
foot segment toward a target. They have
lowest kicking velocities but force
advantage due to co-activations of flexors
and extensors at hip and knee joints. This
indicates force advantage in generating
kicking power. Combined kicks (HO and
BH) have decent velocities as well as coactivations
of flexor and extensor muscles.
Therefore, they have both velocity and force
advantages in power generation during
kicking. However, the complexity of leg
motion does not allow the beginners to learn
them easily. The highest kicking speed and
consistent pattern of angle-angle plot
support the popularity of roundhouse kick
(RH) among various kicks in Taekwondo.
SwingkickThrustkickCombined
kick
REFERENCES
Putnam, C. (1991). Med. Sci. Sport Exerc., 22,
130-144.
Sorensen et al. (1996). J. Sports Sciences, 14,
483-495.