a Département de Kinésiologie , Université de Montréal , Montréal , Canada.
J Sports Sci. 2018 Sep;36(18):2121-2128. doi: 10.1080/02640414.2018.1440513. Epub 2018 Feb 15.
To this day, how shoulder muscles react to a strong fatigue stimulus during dynamic shoulder rotations remains unknown. The aims of this study were to assess the effect of repeated maximal internal-external isokinetic shoulder rotations on shoulder strength and muscle activity. Twenty-four individuals completed a 50-repetition fatiguing isokinetic protocol while electromyography was recorded on eleven muscles of the shoulder girdle. Time-frequency transformation and an ANOVA model using statistical parametric mapping methods were used to analyze shifts in instantaneous median frequency (MDF) between each 10-repetition Blocks. Peak torques decreased in both internal and external rotation (P < 0.01) by 24.8% on average which indicated the presence of fatigue. Significant decrease in MDF (P < 0.01) was observed for pectoralis, middle deltoid, upper, middle and lower trapezius, infraspinatus and subscapularis muscles. The observed fatigue to the periscapular and rotator cuff muscles suggests that shoulder stability could be compromised during repeated shoulder rotations, which could underlie the increased risk of scapular dyskinesis and shoulder impingement during fatiguing tasks. The present study provides a deeper understanding on the manifestations of fatigue within muscles of the shoulder girdle and the results could be applied toward improvements in athlete shoulder injury prevention and rehabilitation programs.
时至今日，人们对于在动态肩部旋转过程中肩部肌肉如何对强烈的疲劳刺激做出反应仍不清楚。本研究的目的是评估重复最大的内外向等速肩部旋转对肩部力量和肌肉活动的影响。24 名个体完成了 50 次疲劳等速协议，同时记录了肩部肩带的 11 块肌肉的肌电图。使用时频变换和基于统计参数映射方法的 ANOVA 模型，分析了每个 10 次重复块之间即时中值频率（MDF）的变化。内旋和外旋的峰值扭矩平均降低了 24.8%（P<0.01），表明存在疲劳。胸大肌、中三角肌、上、中、下斜方肌、肩胛下肌和肩胛下肌的 MDF 显著降低（P<0.01）。肩胛带和肩袖肌肉的观察到的疲劳表明，在重复的肩部旋转过程中，肩部稳定性可能会受到影响，这可能是在疲劳任务中肩胛运动障碍和肩撞击的风险增加的原因。本研究更深入地了解了肩带肌肉中疲劳的表现，研究结果可应用于运动员肩部损伤预防和康复计划的改进。
