Research on Throwing Form Strategies according to Thrown Objects or Body Parameters

Abstract

There are many sports in which throwing motion is used, such as baseball and shot put, but the throwing form differs depending on the individual and the competition. Factors that cause throwing forms to vary among individuals and competitions include differences due to parameters such as the weight of the thrown objects, body inertia, and body size. Although there has been research on throwing motion in specific competitions, no general theory has been established regarding the strategies under which various throwing forms are based. In this research, we examine, consider, and discuss the strategies of throwing form for the baseball and the shot put. Using reinforcement learning, we derived throwing forms for high-speed throwing according to parameters. The relationship between parameters and throwing forms was then compared and analyzed. As a result of comparing the optimally differentiated throwing forms for each parameter, the throwing form strategy due to differences in the weight of thrown objects may differ in terms of the angle of the upper arm at release and the angular acceleration of the shoulder and elbow, and the strategy due to the degree of push of the arm and the influence of the forearm and upper arm. Throwing form strategy due to differences in body size may also include differences in strategy due to the influence of the amount of torque applied to rotate the arm depending on the length of the moment arm and the speed at which the forearm and upper arm are rotated, in terms of the timing of elbow advancement and the angular acceleration of the shoulder and elbow.