Mirabito Nicholas S, Topley Matthew, Thomas Stephen J
Department of Kinesiology, Temple University, Philadelphia, Pennsylvania, USA.
Department of Exercise Science, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
Am J Sports Med. 2022 Apr;50(5):1382-1388. doi: 10.1177/03635465221083325. Epub 2022 Mar 14.
Acute adaptations in clinical measures of range of motion and strength have been found after baseball pitching; however, there is a lack of research concerning the physiological mechanism responsible for these changes. Adaptations in muscle architecture of the infraspinatus and teres minor may serve as the structural changes responsible for these clinical measure changes.
To longitudinally assess the acute changes in range of motion, strength, and muscle architecture of the infraspinatus and teres minor muscles in baseball pitchers after a simulated baseball game. Additionally, we examined the relationship between muscle architecture and changes in clinical measures of range of motion and strength.
Controlled laboratory study.
Ten healthy nonvarsity collegiate club baseball pitchers (mean ± SD; age, 20.1 ± 1.10 years) were examined pre-pitching, immediately after pitching, and each subsequent day for 5 days after pitching in a simulated baseball game. A digital inclinometer and handheld dynamometer were used to assess range of motion and strength, respectively. Diagnostic ultrasound was used to assess pennation angle and muscle thickness of the infraspinatus and teres minor at rest and at maximal contraction.
Internal rotation range of motion significantly decreased immediately and did not return to baseline until 4 days after pitching (≤ .05). External rotation strength also immediately decreased and returned on the third day after pitching (≤ .05). Moreover, the resting pennation angle of the superficial and deep portions of the infraspinatus increased immediately after pitching, with the superficial portion returning to baseline on day 4 and the deep portion returning on day 5 (≤ .05). Furthermore, the pennation angle changes of the infraspinatus and thickness of the teres minor were predictive of the loss of internal rotation range of motion after pitching ( = 0.419; ≤ .05).
This study found diminished internal rotation range of motion and external rotation strength after pitching, with alterations in muscle architecture of the infraspinatus. The pennation angle increase in the infraspinatus at rest is indicative of increased tension in the muscle, which was found to be the underlying mechanism for the clinical loss of internal rotation range of motion. This was demonstrated by the inverse relationship between internal rotation range of motion and the pennation angle of the superficial and deep fibers of the infraspinatus.
Clinicians should consider recovery time after pitching to prevent chronic losses of shoulder range of motion and strength. Identification of the underlying mechanisms of range of motion loss after pitching allows clinicians to optimize recovery strategies in baseball pitchers.
棒球投球后，已发现运动范围和力量的临床测量指标出现急性适应性变化；然而，关于导致这些变化的生理机制的研究却很缺乏。冈下肌和小圆肌的肌肉结构适应性变化可能是导致这些临床测量指标变化的结构改变。
纵向评估模拟棒球比赛后棒球投手冈下肌和小圆肌的运动范围、力量及肌肉结构的急性变化。此外，我们还研究了肌肉结构与运动范围和力量的临床测量指标变化之间的关系。
对照实验室研究。
对10名健康的非校队大学俱乐部棒球投手（平均±标准差；年龄，20.1±1.10岁）在投球前、投球后即刻以及投球后的5天里每天进行检查。分别使用数字倾角仪和手持测力计评估运动范围和力量。使用诊断超声评估冈下肌和小圆肌在静息和最大收缩时的羽状角和肌肉厚度。
内旋运动范围在投球后即刻显著减小，直到投球后4天才恢复到基线水平（P≤0.05）。外旋力量也在投球后即刻下降，并在投球后第三天恢复（P≤0.05）。此外，投球后冈下肌浅部和深部的静息羽状角即刻增加，浅部在第4天恢复到基线水平，深部在第5天恢复（P≤0.05）。此外，冈下肌的羽状角变化和小圆肌的厚度可预测投球后内旋运动范围的损失（r = 0.419；P≤0.05）。
本研究发现投球后内旋运动范围和外旋力量减小，同时冈下肌的肌肉结构发生改变。冈下肌静息时羽状角增加表明肌肉张力增加，这被发现是内旋运动范围临床损失的潜在机制。冈下肌浅部和深部纤维的羽状角与内旋运动范围之间的负相关关系证明了这一点。
临床医生应考虑投球后的恢复时间，以防止肩部运动范围和力量的慢性损失。确定投球后运动范围损失的潜在机制使临床医生能够优化棒球投手的恢复策略。
