Michener Lori A, Sharma Sapna, Cools Ann M, Timmons Mark K
Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, USA.
Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, USA.
J Shoulder Elbow Surg. 2016 Nov;25(11):1861-1867. doi: 10.1016/j.jse.2016.04.010. Epub 2016 Jun 30.
Coordinated muscle activity is needed for synchronized joint motion and stability. Characterizing relative scapular muscle activity deficits in participants with shoulder pain will provide foundational knowledge to develop rehabilitation programs.
Participants were recruited with subacromial pain syndrome and an asymptomatic control group matched for age, gender, and dominant arm (N = 56). Surface electromyographic muscle activity was recorded from the upper, middle, and lower trapezius (UT, MT, LT) and serratus anterior (SA) during 5 repetitions of a weighted arm elevation task. Muscle activity was normalized to a reference contraction and then expressed as UT/MT, UT/LT, UT/SA, and LT/SA ratios. Ratios were compared between groups and across 3 arm angle intervals during ascending and descending elevation.
A 2 × 3 mixed-model analysis of variance yielded a group main effect for the UT/LT ratio, with a higher ratio in the subacromial pain group during ascending (mean difference, 0.92; P = .008) and descending (mean difference, 0.70; P = .030). For the LT/SA ratio, there was a group effect: a lower ratio in the subacromial group during ascending (mean difference, -0.25; P = .026) and descending (mean difference, -0.51; P = .032). There were no differences for the UT/MT or UT/SA.
There is a disruption in coordination between the LT and SA and the UT and LT during an arm elevation task in patients with subacromial pain syndrome. The LT was part of both altered ratios, indicating the relative importance of the LT. Future research should determine if exercises aimed at restoring the dysfunctional LT/SA and UT/LT force couples are beneficial to reduce shoulder pain and disability in patients with unilateral shoulder pain.
协调的肌肉活动对于关节同步运动和稳定性是必需的。明确肩痛患者相对肩胛肌活动缺陷将为制定康复计划提供基础知识。
招募患有肩峰下疼痛综合征的参与者以及年龄、性别和优势手臂相匹配的无症状对照组（N = 56）。在进行5次负重手臂抬高任务的过程中，记录斜方肌上、中、下肌（UT、MT、LT）和前锯肌（SA）的表面肌电活动。将肌肉活动标准化为参考收缩，然后表示为UT/MT、UT/LT、UT/SA和LT/SA比值。在上升和下降抬高过程中，比较两组之间以及3个手臂角度区间的比值。
两因素三水平混合方差分析显示，UT/LT比值存在组间主效应，肩峰下疼痛组在上升（平均差异，0.92；P = 0.008）和下降（平均差异，0.70；P = 0.030）过程中该比值更高。对于LT/SA比值，存在组间效应：肩峰下组在上升（平均差异，-0.25；P = 0.026）和下降（平均差异，-0.51；P = 0.032）过程中该比值更低。UT/MT或UT/SA比值无差异。
肩峰下疼痛综合征患者在手臂抬高任务中，LT与SA以及UT与LT之间的协调性受到破坏。LT是两个改变比值中的一部分，表明了LT的相对重要性。未来研究应确定旨在恢复功能失调的LT/SA和UT/LT力偶的运动是否有助于减轻单侧肩痛患者的肩部疼痛和功能障碍。
