Discipline of Biomedical Science, School of Medical Sciences, Sydney Medical School, The University of Sydney, Sydney, Australia.
Clin Anat. 2011 Jul;24(5):619-26. doi: 10.1002/ca.21123. Epub 2011 Jan 12.
Although flexion is a common component of the routine clinical assessment of the shoulder the muscle recruitment patterns during this movement are not clearly understood making valid interpretation of potential muscle dysfunction problematic. The purpose of this study was to comprehensively examine shoulder muscle activity during flexion in order to compare the activity levels and recruitment patterns of shoulder flexor, scapular lateral rotator and rotator cuff muscles. Electromyographic (EMG) data were recorded from 12 shoulder muscles sites in 15 volunteers. Flexion was performed in standing in the sagittal plane at no load, 20%, and 60% of each subject's maximum load. EMG data were normalized to maximum values obtained during maximum voluntary contractions. Results indicated that anterior deltoid, pectoralis major, supraspinatus, infraspinatus, serratus anterior, upper, and lower trapezius were activated at similar moderate levels. However, subscapularis was activated at low levels and significantly lower than supraspinatus and infraspinatus. Similar activity patterns across time were demonstrated in the muscles that produce flexion torque, laterally rotate the scapula, as well as supraspinatus and infraspinatus, and did not change as flexion load increased. The onset of activity in supraspinatus and anterior deltoid occurred at the same time and prior to movement of the limb at all loads with infraspinatus activity also occurring prior to movement onset at the medium and high load conditions only. Posterior rotator cuff muscles appear to be counterbalancing anterior translational forces produced during flexion and it would appear that supraspinatus is one of the muscles that consistently "initiates" flexion.
虽然屈曲是肩部常规临床评估的常见组成部分，但对于该运动中肌肉募集模式仍不明确，这使得潜在肌肉功能障碍的解释变得困难。本研究的目的是全面检查肩部屈曲时的肌肉活动，以比较肩屈肌、肩胛外侧旋转肌和肩袖肌肉的活动水平和募集模式。在 15 名志愿者中，从 12 个肩部肌肉部位记录肌电图（EMG）数据。在无负荷、20%和 60%最大负荷下，在矢状面站立进行屈曲。EMG 数据被归一化为最大自愿收缩期间获得的最大值。结果表明，三角肌前束、胸大肌、冈上肌、冈下肌、前锯肌、上斜方肌和下斜方肌以相似的中等水平被激活。然而，肩胛下肌的激活水平较低，明显低于冈上肌和冈下肌。产生屈曲扭矩的肌肉、肩胛外侧旋转肌以及冈上肌和冈下肌的活动模式在整个时间内相似，并且随着屈曲负荷的增加而没有改变。在所有负荷下，冈上肌和三角肌前束的活动起始时间相同，并先于肢体运动，只有在中高负荷条件下，冈下肌的活动也先于运动起始。后部肩袖肌肉似乎在平衡屈曲期间产生的前向平移力，并且似乎冈上肌是始终“启动”屈曲的肌肉之一。
