Kinematic analysis of the side kick in Taekwon-do.

The aim of the paper is to present the analysis of the influence of chosen kinetic factors on the side-kick technique. This issue is of a significant importance in the traditional version of Taekwon-do, where a single strike may reveal the winner. A male athlete, a black-belt holder, has participated in this case study. Generally accepted criteria of sports technique biomechanical analysis were adhered to. The athlete executed a side kick four times (in Taekwon-do terminology referred to as yop chagi) in a way most typical of his usual kick execution in board breaking. The parameter values obtained were used to determine the individual curves of the changes in velocities in the function of relative extension length of the kicking leg. The maximum knee and foot velocities in the Cartesian coordinate system were determined. The leg lifting time and the total time of kick execution as well as the maximum force which the foot exerted on the ground were also determined. On the basis of the values obtained the average values and the standard deviation were calculated. The correlation dependence (r = 0.97) shows that a higher knee velocity significantly affects the velocity which the foot develops and that the total time of kick execution depends on the velocity which the knee develops in the leg lifting phase (r = 0.75). The average maximum speed was obtained at the length of the leg equal to 82% of the maximum length of the fully extended leg. In the kicking technique used by the athlete, this length can be considered for this athlete the optimum value for achieving the maximum strike dynamics.