118 Effect of various thrown baseball trajectories on the bat impact point in baseball

Abstract

This study examined the impact of different trajectories of a thrown baseball on batting accuracy, and discusses the actions taken by the batter that affected the accuracy of the impact. Seven university baseball players hit baseballs thrown in various trajectories, and four synchronized high-speed video cameras were used to record the hits. The movement of the bat, ball, and batter's body were analyzed by three-dimensional direct linear transformation. The results of the analysis were as follows: 1) The point of impact between the ball and the bat varied according to the ball's trajectory, suggesting that maintaining a constant impact point on the bat is difficult. 2) Batters compensated for changes in ball trajectory mainly by altering the rotation angle of the hips and shoulders. Especially for inside or high trajectories, larger hip and shoulder rotations were necessary, allowing batters to begin the batting motion earlier. 3) Batters needed to actively judge the ball's trajectory, which gave them less time to execute their swing.