Department of Physical Therapy, Ibaraki Prefectural University of Health Sciences , Ami, Japan.
Faculty of Health and Sport Sciences, University of Tsukuba , Tsukuba, Japan.
Sports Biomech. 2020 Aug;19(4):452-466. doi: 10.1080/14763141.2018.1497195. Epub 2018 Aug 13.
The aim of this study was to investigate the kinetic functions of the lower limbs at different hitting-point heights to provide key information for improving batting technique in baseball players. Three-dimensional coordinate data were acquired using a motion capture system (250 Hz) and ground reaction forces were measured using three force platforms (1000 Hz) in 22 male collegiate baseball players during tee-batting set at three different hitting-point heights (high, middle, and low). Kinetic data were used to calculate joint torque and mechanical work in the lower limbs by the inverse dynamics approach. The peak angular velocity of the lower trunk about the vertical axis was smaller under the low condition. The joint torques and mechanical works done by both hip adduction/abduction axes were different among the three conditions. These results indicate that hip adduction/abduction torques mainly contribute to a change in the rotational movement of the lower body about the vertical axis when adjusting for different hitting-point heights. In order to adjust for the low hitting-point height which would be difficult compared with other hitting-point heights, batters should focus on rotating the lower trunk slowly by increasing both hip abduction torques.
本研究旨在探讨不同击球点高度下下肢的动力学功能，为棒球运动员提高击球技术提供关键信息。在 22 名男性大学生棒球运动员进行 Tee 击球时，使用运动捕捉系统（250Hz）获取三维坐标数据，并使用三个力台（1000Hz）测量地面反作用力，设置三个不同的击球点高度（高、中、低）。动力学数据通过逆动力学方法用于计算下肢关节扭矩和机械功。在低位条件下，下躯干绕垂直轴的峰值角速度较小。在三个条件下，髋关节内收/外展轴的关节扭矩和机械功不同。这些结果表明，在调整不同击球点高度时，髋关节内收/外展扭矩主要有助于改变身体下部绕垂直轴的旋转运动。为了适应与其他击球点高度相比更困难的低击球点高度，击球手应该通过增加髋关节外展扭矩来缓慢地旋转下躯干。
