1Department of Exercise Science, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY; 2Baltimore Orioles, Major League Baseball, Baltimore, MD; and 3Department of Kinesiology, School of Education and Human Services, Canisius College, Buffalo, NY.
Med Sci Sports Exerc. 2014 Mar;46(3):565-71. doi: 10.1249/MSS.0b013e3182a79cd9.
Overexertion caused by increased pitch counts can evoke protective biomechanical responses signified by decreased ball velocity, such as reduced throwing arm kinematics and kinetics. Among skilled pitchers, overexertion may not always present ball velocity decrements, because compensatory throwing biomechanics aid in maintaining peak ball velocity although lowering physiologic stress.
Nineteen pitchers (collegiate and elite high school), randomly crossed over to pitch two simulated games at ± 25% of their desired stride length, were recorded by an eight-camera motion capture system (240 Hz) integrated with two piezoelectric force plates (960 Hz) and a professional model radar gun. HR, self-reported exertion scores, blood glucose and lactate, salivary biomarkers, peak linear hand and fastball velocities were examined. Repeated-measures ANOVA as well as independent and pairwise t-tests examined significant differences (P ≤ 0.05).
Shortened strides reduced mean pitching HR by 11.1 bpm (P < 0.001), improved recovery capacity by 5.76% (P = 0.012), and lowered salivary cortisol from baseline (P = 0.001). Physiologic stress elevated with greater strides, because salivary alpha amylase was significantly elevated from baseline (P = 0.011) with no improvements evidenced in pitching HR or recovery capacity. Linear hand and ball velocities remained equivalent between stride conditions.
Stride length can affect physical exertion without disrupting ball velocity, where shortening strides can plausibly respond to competitive exertion in baseball pitchers. Current pitch count standards and radar velocity accounts have not been proven efficacious in predicting exertion in professional and collegiate baseball, where biomechanical compensations arise to maintain ball velocity. In some instances, compensatory adaptations may be pathomechanic where future research identifying injurious movement patterns can advance injury prevention in professional baseball.
增加投球次数引起的过度劳累会引起保护性的生物力学反应，表现为球速降低，如投掷臂运动学和动力学的降低。在熟练的投手中，过度劳累并不总是表现为球速下降，因为补偿性的投掷生物力学有助于在降低生理压力的同时保持峰值球速。
19 名投手（大学生和精英高中）随机交叉以±25%的期望步长进行两次模拟比赛，通过一个由 8 个摄像机的运动捕捉系统（240Hz）与两个压电测力板（960Hz）和一个专业模型雷达枪集成记录。测量了心率（HR）、自我报告的用力评分、血糖和乳酸、唾液生物标志物、峰值线性手和快球速度。采用重复测量方差分析以及独立和成对 t 检验来检查显著差异（P≤0.05）。
缩短步长使平均投球 HR 降低了 11.1 bpm（P＜0.001），恢复能力提高了 5.76%（P=0.012），并且使唾液皮质醇从基线下降（P=0.001）。生理应激随着更大的步长而增加，因为唾液淀粉酶从基线显著升高（P=0.011），而投球 HR 或恢复能力没有改善。线性手和球速在步长条件之间保持不变。
步长可以影响体力消耗而不影响球速，缩短步长可以合理应对棒球投手的竞技性用力。目前的投球次数标准和雷达速度计数并没有被证明在预测职业和大学生棒球的用力方面有效，在这种情况下，生物力学补偿会出现以维持球速。在某些情况下，补偿性适应可能是病理性的，未来研究确定有损伤的运动模式可以促进职业棒球的损伤预防。
