EFFECTIVE TIMING OF EXERTING JOINT TORQUES TO OBTAIN BASEBALL BAT HEAD SPEED

The purpose of this study was to quantify the effective timings of exerting joint torques for obtaining a large bat head speed at the ball impact in baseball batting motion. Twelve baseball batters performed hitting a teed ball as strongly as possible. The whole-body segments with bat were modelled as a system of sixteen-rigid linked segments. The kinematic and kinetic data were measured with the motion capture system with 3 force platforms and an instrumented bat. The major contributors were calculated using the equation of the whole-body motion considering the generating factors of the motion-dependent term. Since the instances when the individual contributions show peak values differ among the contributions of the major positive contributors, effective timings of exerting large joint torques exist for obtaining a large head speed at the ball impact