Kaizu Yoichi, Sato Ena, Yamaji Takehiko
Hidaka Hospital: 886 Nakao-machi, Takasaki, Gunma 370-0001, Japan.
Department of Rehabilitation Sciences, Gunma University Graduate School of Health Sciences, Japan.
J Phys Ther Sci. 2020 Dec;32(12):816-822. doi: 10.1589/jpts.32.816. Epub 2020 Dec 11.
[Purpose] The purpose of this study was to determine the relationship between pitching weight and pitching mechanics, including ball reaction force (BRF) and temporal parameters, for the prevention of throwing injury in adult amateur pitchers. [Participants and Methods] Twenty adult male amateur pitchers (mean age, height, and body mass: 26 ± 3.4 years, 1.7 ± 0.03 m, and 71.6 ± 9.5 kg, respectively) randomly pitched light (110 g) and heavy (145 g) baseballs at maximum velocity. Kinematic, kinetic, and temporal parameters were compared between the light and heavy balls. [Results] Pitching heavy balls significantly increased the BRF to 9.2 N and maximum trunk rotation angular velocity to 26.2°/sec, and decreased the ball speed to 1.4 m/sec and upper limb joint torque efficiency and shoulder internal rotation angular velocity at the moment of ball release at 250.8°/sec. Furthermore, the peak temporal kinetic parameters until ball release appeared early in the throwing of the heavy ball. [Conclusion] Adult amateur pitchers who pitched heavy balls had greater BRF; had decreased upper limb joint torque efficiency, ball speed, and arm angular velocity; and reached maximum kinetics early. Adult amateur pitchers may be at risk of throwing injuries due to throwing of heavy balls.
[目的] 本研究旨在确定投球重量与投球力学之间的关系，包括球反应力（BRF）和时间参数，以预防成年业余投手的投掷损伤。[参与者与方法] 20名成年男性业余投手（平均年龄、身高和体重分别为26±3.4岁、1.7±0.03米和71.6±9.5千克）以最大速度随机投出轻（110克）、重（145克）两种棒球。比较了轻、重两种球的运动学、动力学和时间参数。[结果] 投重球显著增加了球反应力至9.2牛，最大躯干旋转角速度至26.2°/秒，降低了球速至1.4米/秒，以及在球释放瞬间上肢关节扭矩效率和肩部内旋角速度至250.8°/秒。此外，在投重球时，球释放前的峰值时间动力学参数出现得更早。[结论] 投重球的成年业余投手具有更大的球反应力；上肢关节扭矩效率、球速和手臂角速度降低；并且更早达到最大动力学状态。成年业余投手可能因投重球而面临投掷损伤的风险。
