A-44 野球のバント動作におけるバットコントロール(野球4(打撃))

抄録

A bunt is a special type of offensive technique in baseball. The sacrifice bunt is most often used in close, low-scored games. The primary goal in bunt is to ground the ball into fair territory. The batter is required to make contact with the ball at a particular place and time by moving bat and hit the ball toward the appropriate area. Different from hitting, the batter had to control the velocity of hit ball. The purpose of this research was to investigate the temporal and spatial bat positions during the operation of baseball bunt. The subjects were seven university baseball players. As the conditions of the direction of the hit ball, we difined three conditoins, bunt toward first- base, pitcher, and third-base. Each trial was judged whether the trial was success or failure on the basis of hit ball direction, velocity, and the angle of hit ball in the vertical plane and only successful trials were analyzed. The height of the pitched ball was classified into three conditions, high, middle, and low conditions. The three-dimensional positions of the head and grip of the wooden bat were recorded using the VICON512 system (120Hz). At the time of impact, not only bat head but also grip position differed due to the direction of the hit ball. When subjects hit the ball toward the third-base, the position of the bat head preceded the grip. The difference of the horizontal bat position was observed from the beginning of the operation among the theree conditions. The subjects also moved the position of both the bat head and the grip in order to adapt to the height of the pitched ball, using lower limb movement.