Iino Yoichi, Fukushima Atsushi, Kojima Takeji
Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Tokyo, Japan.
J Appl Biomech. 2014 Aug;30(4):563-73. doi: 10.1123/jab.2013-0304. Epub 2014 Jun 30.
The purpose of this study was to investigate the relevance of hip joint angles to the production of the pelvic rotation torque in fast-pitch softball hitting and to examine the effect of ball height on this production. Thirteen advanced female softball players hit stationary balls at three different heights: high, middle, and low. The pelvic rotation torque, defined as the torque acting on the pelvis through the hip joints about the pelvic superior-inferior axis, was determined from the kinematic and force plate data using inverse dynamics. Irrespective of the ball heights, the rear hip extension, rear hip external rotation, front hip adduction, and front hip flexion torques contributed to the production of pelvic rotation torque. Although the contributions of the adduction and external rotation torques at each hip joint were significantly different among the ball heights, the contributions of the front and rear hip joint torques were similar among the three ball heights owing to cancelation of the two torque components. The timings of the peaks of the hip joint torque components were significantly different, suggesting that softball hitters may need to adjust the timings of the torque exertions fairly precisely to rotate the upper body effectively.
本研究的目的是调查快投垒球击球时髋关节角度与骨盆旋转扭矩产生之间的相关性，并研究球的高度对这种扭矩产生的影响。13名高水平女子垒球运动员击打三个不同高度的固定球：高、中、低。骨盆旋转扭矩定义为通过髋关节作用在骨盆上绕骨盆上下轴的扭矩，使用逆动力学从运动学和测力板数据中确定。无论球的高度如何，后髋关节伸展、后髋关节外旋、前髋关节内收和前髋关节屈曲扭矩都有助于骨盆旋转扭矩的产生。尽管每个髋关节的内收和外旋扭矩的贡献在不同球高度之间存在显著差异，但由于两个扭矩分量的抵消，前后髋关节扭矩的贡献在三个球高度之间相似。髋关节扭矩分量峰值的时间显著不同，这表明垒球击球手可能需要相当精确地调整扭矩施加的时间，以有效地旋转上半身。
