PAPER ON BIOMECHANICS OF TAEKWON-DO
"Analysis of the Jumping High Kick" BY MASTER CHOONG TECK HONG, PKT, PJM, 7TH DEGREE BLACK BELT AND ROLAND CHOONG TAEKWON, 6TH DEGREE BLACK BELT
Roland Choong Taekwon, 6th Degree Black Belt demonstrating the High Jumping Side Kick
INTRODUCTION
The science of biomechanics is concerned 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 technique. It is our hope that our research would contribute to the betterment of taekwon-do.
THE HIGH JUMPING SIDE KICK
In the high jumping side kick, the height that a taekwondoist achieves is divided into two parts.
1. The height of the taekwondoist's centre of gravity at the take off position.
2. The height that the taekwondoist raises his centre of gravity after he has taken off.
The height of the centre of gravity during the take off position depends on the taekwondoist's physique and his starting body position. Long-legged taekwondoists have high centre of gravity and as such have an advantage. The advantage will be more if he had long legs relative to the trunk.
The height that the centre of gravity rises to is however governed by his vertical velocity and the vertical impulse transmitted through his jumping leg during take off.
Vertical velocity means the speed at which the body moves upwards.
In algebraic form :
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s = l/t where;
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s is average speed, 1 is the length of the path covered and t is the time. Thus the vertical velocity is obtained by dividing the displaced upthrust by the time taken.
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v = d/t where;
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v is the average velocity, d is the displacement upward and t is the time.
Vertical impulse means the force that the taekwondoist exerts on the ground when the body moves upwards.
The magnitude of 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 rotation of the body to assume the required position for the high 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 that the shorter the time of take off, the greater the vertical 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 extension, 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 stabilize his speed and also depending on the 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. One could 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 bought from a forward position to one that is inclined backward. With the 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 last 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, with one arm forward and one arm backward (using the one arm swing take-off). Once the jumping foot is grounded, the jumping knee flexes to put the leg in a forceful extension. The leg that has been deliberately left behind during the last stride begins to swing forward, contributing to the vertical velocity. He then rotates the body to the left (right leg execution), bends 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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