1988 年 21 巻 1 号 p. 31-39
The purpose of this study is to investigate the causes of the right heel problems in Kendo players. Ten three-Dan Kendo players were examined as subjects in the current study - five with right heel problems and the other five with no right heel problems. The shomen-uchi (stepping-in motion) movement was investigated. Force components along X, Y and Z axes of right foot force were measured by use of a forceplate, and the forms of the movement were filmed utilizing a 16mm high-speed cinecamera (400frame/s), simultaneously. Next, the foot force data were sampled with a sampling period of 0.28ms, and processed by use of a low-pass filter with a cut-off frequency of 400Hz. Based on the images in the film, the coordinates of the important points of the bodies of the players were picked up utilizing a motion analyzer. Then the angles of important parts of the body from the vertical line and the center of gravity of the body were calculated, and analyzed statistically.
The results are summarized as follows:
1. The mean values of the maximum foot force and maximum foot acceleration of the players with heel problems are larger than those of players without heel problems. In particular, the mean value of the downward component of maximum acceleration of players with heel problems is larger than that of players without problems.
2. The striking action of players with heel problems and those without heel problems differ in the upper body (before foot contact), the head, trunk and lower body (after foot contact).
3. With respect to the striking action of players with heel problems, it has been observed that the attitude of the right lower leg is near the vertical, the trunk leans forward, the head backward, the forearm tilts upward, and the shinai is held near horizontally. This has been seen both before and after foot contact.
4. In players with heel problems, the angular changes in both the right ankle and right knee joint were smaller than the angular changes in joints of players with no heel problems. It is therefore surmised that the less the angular change of the ankle and knee of the forward foot, the greater is the chance of heel problems.