野球のバットの軌道及びそれに影響する打撃動作の類型化の試み
1996 年 9 巻 1 号 p. 127-139
詳細
1996 年 9 巻 1 号 p. 127-139
The purpose of this study was to identify types of batting motions and the movement of the bat in baseball. The subjects were 10 baseball players; 7 amateur players of university baseball teams, 1 semiprofessional player of a club team, 2 players of the Cuban national team. Their batting motions were analized with films of two high speed video cameras. The main results are as the followings;
1. The speeds of the head of a bat just before the impact were 25.0-34.0(m/s) for the players of the university teams, and 35.9-37.1 (m/s) for the others.
2. The trajectory of a bat were identified as almost a circle throughout a swing in the horizontal plane for both long-hitting players and those with high-hitting-average.
Players with high-hitting-average tended to have smaller radiuses of gyration of a bat than long-hitting plyers.
3. Two types were identified in terms ofaxes of shoulder ri10vements in the horizontal plane; fixed at the center of shoulders, and moving from the right shoulder to the left. (All subjects were right-handed batters.)
4. Three types were identified in terms of axes of hip movements in the horizontal plane; right end of hip, left end of hip, and the center of hip. (“hip" means the line between hip joints.)
5. Two types were identified in teηns of the timing of the hip movements; one starting in the first part of the swing, and the other starting just before the impact.
