In this study, the degrees in mastery of the throwing techniques in Judo were examined by the changes in partial foot pressure during the throwing motion. The subjects were grouped into following three;
A) Judoists with favorite of Seoi-nage
B) Judoists without favorite of Seoi-nage
C) Beginners
The maximum value of partial foot pressure, its timing, duration, and impulse in Seoi-nage were measured. In order to measure the above items, the force sensor made of carbon fibers was attached to the head of 1 st and 5 th metatarsal, and calcaneum of both feet.
Following findings were obtained.
1. Regarding to the Group A and B, the changes in pressure, timing, and maximum value of pressure were consistent. Both groups showed their maximum values of partial foot pressure in the stage of throwing motion. On the other hand, the Group C was indicated to have the large variability in the maximum value of partial foot pressure.
2. The functional foot was indicated to produce high pressure (especially in the heads of 1 st and 5 th metatarsal) during “Fumikomi” in all three groups. The supporting foot was indicated to show a great change in pressure in process of “Kake” to “Nage”in three groups. The records of 5 th metatarsal head indicated doublepeaked pressure and that of calcaneum did mountain-shaped pressure.
3. The maximum values of partial foot pressure and of impulse per unit body weight were found to be greater in the supporting foot than in the functional foot. The Group A showed the greatest value of pressure by the head of 5 th metatarsal, and that of the head of 1 st metatarsal followed. The supporting foot in the Group A was indicated to generate the greatest pressure in calcaneum. Regarding to the Group B, both supporting and functional feet were found to show the greatest value of pressure in the head of 1 st metatarsal and then the head of 5 th metatarsal. Regarding to the Group C, both supporting and functional feet showed the greatest value of pressure in the head of 1 st metatarsal and a great value of impulse in the calcaneum.
4. The Group A showed relatively low values of coefficient of variation in maximum pressure and impulse except for the heads of 5 th metatarsal of both feet. The Group B was found to have less variation (c. v. ) than the Group C did.
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