Kiai and Mechanical Characteristics of Some Karate Punches

Abstract

In the studies from the aspect of biomechanics the essential data can be found in the field of the punches -motions which are characterized as precise, fast and maximally forced. In the study of Yoshihuku (1984) it was found that the duration of the force was concentrated between 16 and 19 ms regardless of the kind of the techniques, implying that the human body that was not rigid took the above time to transmit its momentum to the target. In the research about the flow of the energy from trunk to arm in Tsuki movement (Yoshihuku, Ikegami, Sakurai, 1984) it is pointed out that the main source of energy in Tsuki movement is not in the upper arm itself, but in the other parts of the body. It is interesting that in each trial the first hit the target with its maximum velocity, just or nearly at the moment when both the energy flow and the kinetic energy reached their maximum velocity. In the study about the central regulation problems of the human motion abilities in the biomechanical structures (Chaidze, 1966) it is pointed out that the reduction of the velocity in the arm extension is necessary before the collision, with purpose to fix the joints and to increase the mass included in the punch. Thc value of the collision impulse depends on the movement velocity in the moment of the collision (vc), and the mass of the body included in the punch (the equivalent mass -em). Because of this and some other conditions characteristical for karate combats, this parameters should be improved during the training sessions. It might be that Kiai is one of the factors which enables better demonstration of these values. That is why the subject of this study is Kiai, the phenomenon which is relatively unexplored up to now, or in other words, its influence on mechanical characteristics of karate punches Gyaku Tsuki and Tettsui Uchi. The need for such of study originated from the importance which is given to Kiai in the rules of sports karate combats. It is well known that Kiai is also an unavoidable companion in Tameshi Wari breaking techniques. The purpose of the present study is to establish possible differences between mechanical characteristics of the chosen punches.