Although the lift force (FL) on a spinning baseball has been analyzed in previous studies, no study has analyzed such forces over a wide variety of spins. The purpose of this study was to describe the relationship between FL and spin for different types of pitches thrown by collegiate pitchers. Four high-speed video cameras were used to record flight trajectory and spin for 7 types of pitches. A total of 75 pitches were analyzed. The linear kinematics of the ball was determined at 0.008-s intervals during the flight, and the resultant fluid force acting on the ball was calculated with an inverse dynamics approach. The initial angular velocity of the ball was determined using a custom-made apparatus. Equations were derived to estimate the FL using the effective spin parameter (ESp), which is a spin parameter calculated using a component of angular velocity of the ball with the exception of the gyro-component. The results indicate that FL could be accurately explained from ESp and also that seam orientation (4-seam or 2-seam) did not produce a uniform effect on estimating FL from ESp.
Tomoyuki Nagami, Takatoshi Higuchi, Hiroki Nakata, Toshimasa Yanai, and Kazuyuki Kanosue are with the Faculty of Sport Sciences, Waseda University, Tokorozawa, Saitama, Japan. Takatoshi Higuchi is also a Research Fellow of the Japan Society for the Promotion of Science, Tokyo, Japan. Hiroki Nakata is also with the Department of Human Sciences, Faculty of Letters, Nara Women’s University, Nara, Japan.