McQuade K J, Dawson J, Smidt G L
Program in Physical Therapy, New York Medical College, Valhalla 10595, USA.
J Orthop Sports Phys Ther. 1998 Aug;28(2):74-80. doi: 10.2519/jospt.1998.28.2.74.
Clinical examinations and biomechanical analysis of the shoulder often include an assessment of the scapulohumeral rhythm. It is important to understand factors which may affect the scapulohumeral rhythm so that optimal diagnostic and therapeutic strategies can be devised. The purpose of this study was to determine if the scapulohumeral rhythm, when assessed under dynamic conditions, is altered as a result of a fatigue-inducing exercise. Twenty-five subjects were required to elevate their arm against maximum resistance until they were no longer able to completely elevate their arm. Three-dimensional kinematics were measured using an electromagnetic tracking system. Electromyographic activity was recorded from the upper trapezius, lower trapezius, serratus anterior, and the middle deltoid muscles. Power frequency spectrum using the Fast Fourier Transform and the root mean square signal amplitudes were determined for each muscle. The scapulohumeral rhythm was determined using least squares regressions of humeral elevation to scapular upward rotation for 20% intervals (phases) of elevation for each subject. The results showed that during the midrange of elevation to maximum elevation [phases 3-5 (60-150 degrees)], the scapulohumeral rhythm decreased with fatigue, and that the decrease in the scapulohumeral rhythm was associated with myoelectric indicators of fatigue (median power frequency). The study suggests that shoulder fatigue affects the way in which the scapula moves concomitantly with the humerus. Fatigue tends to result in increased motion of the scapula, which alters the scapulohumeral rhythm.
肩部的临床检查和生物力学分析通常包括对肩肱节律的评估。了解可能影响肩肱节律的因素很重要，这样才能制定出最佳的诊断和治疗策略。本研究的目的是确定在动态条件下评估时，肩肱节律是否会因疲劳诱导运动而改变。25名受试者被要求在最大阻力下抬高手臂，直到他们无法再完全抬高手臂。使用电磁跟踪系统测量三维运动学。记录上斜方肌、下斜方肌、前锯肌和三角肌中部的肌电活动。对每块肌肉测定使用快速傅里叶变换的功率频谱和均方根信号幅度。通过对每个受试者抬高过程中20%间隔（阶段）的肱骨抬高与肩胛骨向上旋转进行最小二乘回归，确定肩肱节律。结果表明，在从中度抬高到最大抬高的过程中[阶段3 - 5（60 - 150度）]，肩肱节律随着疲劳而降低，并且肩肱节律的降低与疲劳的肌电指标（中位功率频率）相关。该研究表明，肩部疲劳会影响肩胛骨与肱骨协同运动的方式。疲劳往往会导致肩胛骨运动增加，从而改变肩肱节律。
