Escamilla Rafael F, Barrentine Steven W, Fleisig Glenn S, Zheng Naiquan, Takada Yoshihiro, Kingsley David, Andrews James R
Department of Physical Therapy, California State University, Sacramento, CA 95819-6020, USA.
Am J Sports Med. 2007 Jan;35(1):23-33. doi: 10.1177/0363546506293025. Epub 2006 Sep 14.
The effects of approaching muscular fatigue on pitching biomechanics are currently unknown. As a pitcher fatigues, pitching mechanics may change, leading to a decrease in performance and an increased risk of injury.
As a pitcher approaches muscular fatigue, select pitching biomechanical variables will be significantly different than they were before muscular fatigue.
Controlled laboratory study.
Ten collegiate baseball pitchers threw 15 pitches per inning for 7 to 9 innings off an indoor throwing mound during a simulated baseball game. A pitching session ended when each pitcher felt he could no longer continue owing to a subjective perception of muscular fatigue. A 6-camera 3D automatic digitizing system collected 200-Hz video data. Twenty kinematic and 11 kinetic variables were calculated throughout 4 phases of the pitch. A repeated-measure analysis of variance (P < .01) was used to compare biomechanical variables between innings.
Compared with the initial 2 innings, as a pitcher approached muscular fatigue during the final 2 innings he was able to pitch, there was a significant decrease in ball velocity, and the trunk was significantly closer to a vertical position. There were no other significant differences in kinematics or kinetics variables.
The relatively few differences observed imply that pitching biomechanics remained remarkably similar between collegiate starting pitchers who threw between 105 and 135 pitches for 7 to 9 innings and approached muscular fatigue.
This study did not support the idea that there is an increase in shoulder and elbow forces and torques as muscular fatigue is approached. It is possible that if a pitcher remained in a fatigued state for a longer period of time, additional changes in pitching mechanics may occur and the risk of injury may increase.
接近肌肉疲劳时对投球生物力学的影响目前尚不清楚。随着投手疲劳，投球力学可能会改变，导致表现下降和受伤风险增加。
当投手接近肌肉疲劳时，选定的投球生物力学变量将与肌肉疲劳前有显著差异。
对照实验室研究。
10名大学棒球投手在模拟棒球比赛中从室内投球 mound 每局投15球，共投7至9局。当每个投手因主观感觉肌肉疲劳而觉得无法继续时，投球环节结束。一个6摄像头3D自动数字化系统收集200赫兹的视频数据。在投球的4个阶段计算了20个运动学变量和11个动力学变量。使用重复测量方差分析（P <.01）比较各局之间的生物力学变量。
与最初的2局相比，当投手在他能够投球的最后2局接近肌肉疲劳时，球速显著下降，并且躯干显著更接近垂直位置。运动学或动力学变量没有其他显著差异。
观察到的相对较少的差异表明，在投出105至135球、投7至9局并接近肌肉疲劳的大学先发投手中，投球生物力学保持非常相似。
本研究不支持随着接近肌肉疲劳，肩部和肘部的力和扭矩会增加的观点。如果投手在疲劳状态下停留更长时间，投球力学可能会发生额外变化，受伤风险可能会增加。
