National Research Centre for the Working Environment, Copenhagen, Denmark.
J Electromyogr Kinesiol. 2010 Apr;20(2):359-65. doi: 10.1016/j.jelekin.2009.02.009. Epub 2009 Apr 1.
Motor control and learning possibilities of scapular muscles are of clinical interest for restoring scapular muscle balance in patients with neck and shoulder disorders. The aim of the study was to investigate whether selective voluntary activation of intra-muscular parts within the serratus anterior can be learned with electromyographical (EMG) biofeedback, and whether the lower serratus anterior and the lower trapezius muscle comprise the lower scapula rotation force couple by synergistic activation. Nine healthy males practiced selective activation of intra-muscular parts within the serratus anterior with visual EMG biofeedback, while the activity of four parts of the serratus anterior and four parts of the trapezius muscle was recorded. One subject was able to selectively activate both the upper and the lower serratus anterior respectively. Moreover, three subjects managed to selectively activate the lower serratus anterior, and two subjects learned to selectively activate the upper serratus anterior. During selective activation of the lower serratus anterior, the activity of this muscle part was 14.4+/-10.3 times higher than the upper serratus anterior activity (P<0.05). The corresponding ratio for selective upper serratus vs. lower serratus anterior activity was 6.4+/-1.7 (P<0.05). Moreover, selective activation of the lower parts of the serratus anterior evoked 7.7+/-8.5 times higher synergistic activity of the lower trapezius compared with the upper trapezius (P<0.05). The learning of complete selective activation of both the lower and the upper serratus anterior of one subject, and selective activation of either the upper or lower serratus anterior by five subjects designates the promising clinical application of EMG biofeedback for restoring scapular muscle balance. The synergistic activation between the lower serratus anterior and the lower trapezius muscle was observed in only a few subjects, and future studies including more subjects are required before conclusions of a lower scapula rotation couple can be drawn.
肩胛带肌肉的运动控制和学习能力对于恢复颈部和肩部疾病患者的肩胛带肌肉平衡具有重要的临床意义。本研究旨在探讨在肩胛带肌肉中，通过肌电（EMG）生物反馈是否可以学习到选择性主动激活胸小肌的肌内部分，以及下部胸小肌和下部斜方肌是否通过协同激活构成下部肩胛旋转力偶。9 名健康男性通过视觉 EMG 生物反馈练习选择性地激活胸小肌的肌内部分，同时记录胸小肌的四个部分和斜方肌的四个部分的活动。一名受试者能够分别选择性地激活上胸小肌和下胸小肌。此外，有 3 名受试者能够选择性地激活下胸小肌，有 2 名受试者能够选择性地激活上胸小肌。在选择性地激活下胸小肌时，该肌肉部分的活动强度是上胸小肌活动强度的 14.4+/-10.3 倍（P<0.05）。选择性地激活上胸小肌和下胸小肌时，对应的比值为 6.4+/-1.7（P<0.05）。此外，选择性地激活下胸小肌的下部会引起下部斜方肌的协同活动，其强度比上部斜方肌高 7.7+/-8.5 倍（P<0.05）。一名受试者完成了双侧胸小肌的完全选择性激活，五名受试者中的 3 名能够选择性地激活单侧胸小肌，这表明肌电生物反馈在恢复肩胛带肌肉平衡方面具有很大的临床应用潜力。只有少数受试者观察到下胸小肌和下部斜方肌之间的协同激活，因此需要进一步研究更多的受试者，才能得出下部肩胛旋转力偶的结论。
