野球投動作のボール速度および角速度生成に対する関節トルクの動力学的な貢献

抄録

The purpose of this study was to quantify dynamic contributions of joint torques to the generation of launched ball parameters (i.e. ball velocity and angular velocity) in baseball pitching. Two types of analytical models, first one is 22-segment model with finger segments taken into consideration and second one is 16-segment model without consideration of finger segments, were proposed to derive the equation of motion for the whole-body system with ball. Dynamics contributions of joint torque, gravity, motion-dependent term(MDT), and modeling error term to the generation of ball state variables such as ball speed and ball angular velocity were quantified using the equation of the target system. Furthermore, the generating factor of the MDT was considered using a recurrent formula derived from the equation. The results in this study indicate that 1) joint torques, especially finger joint torques, are the major contributor to the ball speed when using 22-segment model because finger exerted force directly to the ball, 2) the MDT become the major contributor when using the 16-segment model, and 3) with consideration of the generating factor of the MDT, the horizontal adduction joint torque of the shoulder joint and the extension joint torque of the elbow joint play roles in the generation of ball speed just before ball release.