Analysis of the High Jumping Side Kick
Introduction
The science of biomechanics is concerened with the forces that act on the human body and the effects these forces produce. It is only logical that serious taekwondoists should turn to biomechanics to provide a sound scientific basis for the analysis of taekwon-do techniques.
The High Jumping Sidekick
In the high jumping sidekick, the height that a taekwondoist achieves is divided into two parts
The height of the centre of gravity during the take off depends on the taekwondoist's physique
and his starting position. Long legged taekwondoists have high centre of gravity and as such has
an advantage. The advantage will be more if he has long legs relative to the trunk.
The height that the centre of gravity rises is however governed by his vertical velocity and
the vertical impulse trasnsmitted through his jumping leg during take off.
In algebraic form:
__ l
s = t
__
where s is average speed, l - the length of path covered and t - time. Thus the vertical
velocity is obtained by dividing the displaced upthrust by the time taken.
__ d
v = t
__
where v is average velocity, d - displacement upward and t - time.
Vertical impulse means the force that the taekwondoist exerts on the ground when the body moves upwards.
The magnitude of the vertical impulse depends on the forces involved - the arms, the leading leg, the knee and the ankle joints of his jumping leg. It also depends on factors like the speed with which the limbs move, the muscles of the jumping leg and the way the movements are coordinated. Another factor that influences the magnitude of the vertical forces is the rotating of the body to assume the required position for the jumping side kick and the speed of the extending foreleg. To execute an ideal kick he must be in a good layout position at the peak of the jump. It is also found out that the shorter the time of take off, the greater the veretical lift.
TECHNIQUE
The analysis of the techniques in the high jumping side kick are considered under 4 sub-headings- the run-up, the take-off, the rotation and the landing.
The Run-up
The run-up is to take the taekwondoist into the optimum position for the take-off. The length of the run-up depends on the taekwondoist's ability to stabilise his speed and also depending onthe strength of his leg muscles and his ability to coordinate the movements. By using too long a run-up he may develop more speed than he could control at the take-off and he may have insufficient time to complete his sequence of movements. We would recommend beginners to use 5 to 7 strides and experienced ones to use 7 to 11 strides. The angle of approach is subject to variation. Onecould use a straight line approach or approach the target at an angle of 20 to 40 degrees.
During the last three strides the taekwondoist should adjust his body position in preparation for the
take-off, namely:
1. The trunk should be brought from a foreward position to one that is inclined backward. With
trunk inclined backward, the taekwondoist can take more time to coordinate his movements.
2. The centre of gravity is gradually lowered by the flexion of the knee.
3. There shall be a gradual increase in length of the second stride
The Take-off
The take-off begins with the grounding of the jumping foot at the end of the last stride. At this stage the taekwondoist's body is inclined backward backward, with one arm foreward and one arm backward ( using the one arm swing take-off). Once the jumping foot is grounded, the knee flexe to put the leg in a forceful extension. The leg that has been delibrately left behind during the last stride begins to swing forward, contributing to the vertical force. He then rotates the body to the left ( right leg execution ), bend his knees, ending with a vigorous extension of the kicking leg to the target, the upper body twisted slightly in the direction of the kick.
Landing
The landing is generally made by pulling the extended leg back after delivery.
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