Study of planta shapes and loading points for judo players

Introduction

The nature of Judo competition is to play this competition on an unstable surface of Tatami-mat on bare feet, where, we think, a high balance function of the body to support the load on the toes and plantar surface is required. In general, this balance function is very important for all sports activities, however, it seems that it is especially important for Judo players compared to other athletes. For example, in trying to set some trick on the standing position, it is extremely critical to support the weight load in good balance on the plantar surface under any situation. In these conditions some important questions are: What effects would be caused and how they would be changed on the toes and plantar surface, if the feet alignment on the standing position, which is the very basic posture of the human being, is deformed? In addition, what kind of injuries or dysfunctions would be caused in Judo practices or competitions, when the form of plantar surface is disordered? We evaluated the alignment of feet and plantar surface for all the Judo players belonging to a college Judo club, and investigated the possible correlation between the alignment and the injuries or dysfunctions.

Method

For 200 Judo players belonging to the Judo club of one private university (first through fourth year students), we collected and classified their plantar surface types for 4 years using a foot printer made by SANSHIN KOSAN Co., Ltd.

Discussion

The data collected for Judo players in this study were compared to the data of our previous investigation for ordinary out-patients to the hospitals. The test data for the ordinary out-patients, although their sex and ages were quite different, had indicated, that, in the classification of the longitudinal arch, 65 % of the patients were within " average " and the low arch showed 22 % only. As far as the weight point was concerned, the test result showed a similar higher number of on-heel loading as for Judo players. The test result of the fade part also showed the same data as for the Judo players. Regarding the Judo players investigated in this study, we measured a leg-heel alignment using a degree meter for the players, who had low arch + on-heel loading, in order to more precisely evaluate the inclination of heel, which worked as a fulcrum to twist the frontal part of the feet, and found, that more numbers of Judo players showed a trend of having supinated feet. This means, there were more numbers of Judo players with a low arch, and because of on-heel loading, the frontal part of the feet showed a pronated position with the lower leg in external rotation.