van Trigt Bart, Schallig Wouter, van der Graaff Erik, Hoozemans Marco J M, Veeger Dirkjan
Department of Human Movement Sciences, Faculty of Behavioral and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, 1081 BT Amsterdam, The Netherlands.
Department of Biomechanical Engineering, Delft University of Technology, 2828 CE Delft, The Netherlands.
Sports (Basel). 2018 May 29;6(2):51. doi: 10.3390/sports6020051.
The purpose of this study was to determine whether stride length and knee angle of the leading leg at foot contact, at the instant of maximal external rotation of the shoulder, and at ball release are associated with ball speed in elite youth baseball pitchers. In this study, fifty-two elite youth baseball pitchers (mean age 15.2 SD (standard deviation) 1.7 years) pitched ten fastballs. Data were collected with three high-speed video cameras at a frequency of 240 Hz. Stride length and knee angle of the leading leg were calculated at foot contact, maximal external rotation, and ball release. The associations between these kinematic variables and ball speed were separately determined using generalized estimating equations. Stride length as percentage of body height and knee angle at foot contact were not significantly associated with ball speed. However, knee angles at maximal external rotation and ball release were significantly associated with ball speed. Ball speed increased by 0.45 m/s (1 mph) with an increase in knee extension of 18 degrees at maximal external rotation and 19.5 degrees at ball release. In conclusion, more knee extension of the leading leg at maximal external rotation and ball release is associated with higher ball speeds in elite youth baseball pitchers.
本研究的目的是确定在精英青少年棒球投手的触地瞬间、肩部最大外旋瞬间和投球瞬间，领先腿的步幅和膝关节角度是否与投球速度相关。在本研究中，52名精英青少年棒球投手（平均年龄15.2岁，标准差1.7岁）投出了10个快球。使用三台高速摄像机以240赫兹的频率收集数据。计算领先腿在触地、最大外旋和投球瞬间的步幅和膝关节角度。使用广义估计方程分别确定这些运动学变量与投球速度之间的关联。步幅占身高的百分比以及触地时的膝关节角度与投球速度无显著关联。然而，最大外旋和投球瞬间的膝关节角度与投球速度显著相关。在最大外旋时膝关节伸展增加18度以及在投球瞬间增加19.5度，投球速度会增加0.45米/秒（1英里/小时）。总之，在最大外旋和投球瞬间，领先腿更多的膝关节伸展与精英青少年棒球投手更高的投球速度相关。
