Background

Thoracic spinal manipulation can improve pain and function in individuals with shoulder pain; however, the mechanisms underlying these benefits remain unclear. Here, we evaluated the effects of thoracic spinal manipulation on muscle activity, as alteration in muscle activity is a key impairment for those with shoulder pain. We also evaluated the relationship between changes in muscle activity and clinical outcomes, to characterize the meaningful context of a change in neuromuscular drive.

Methods

Participants with shoulder pain related to subacromial pain syndrome (n = 28) received thoracic manipulation of low amplitude high velocity thrusts to the lower, middle and upper thoracic spine. Electromyographic muscle activity (trapezius-upper, middle, lower; serratus anterior; deltoid; infraspinatus) and shoulder pain (11-point scale) was collected pre and post-manipulation during arm elevation, and normalized to a reference contraction. Clinical benefits were assessed using the Pennsylvania Shoulder Score (Penn) at baseline and 2–3 days post-intervention.

Findings

A significant increase in muscle activity was observed during arm ascent (p = 0.002). Using backward stepwise regression analysis, a specific increase in the serratus anterior muscle activity during arm elevation explained improved Penn scores following post-manipulation (p < 0.05).

Interpretation

Thoracic spinal manipulation immediately increases neuromuscular drive. In addition, increased serratus anterior muscle activity, a key muscle for scapular motion, is associated with short-term improvements in shoulder clinical outcomes.

中文翻译：

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肩峰下疼痛综合征患者脊柱操作后神经肌肉驱动增加的证据

背景

胸椎推拿可以改善肩痛患者的疼痛和功能；然而，这些好处背后的机制仍不清楚。在这里，我们评估了胸椎推拿对肌肉活动的影响，因为肌肉活动的改变是肩痛患者的主要损伤。我们还评估了肌肉活动变化与临床结果之间的关系，以表征神经肌肉驱动力变化的有意义背景。

方法

与肩峰下疼痛综合征相关的肩痛参与者 ( n  = 28) 接受了对下、中和上胸椎的低振幅高速推力的胸部操作。肌电图肌肉活动（斜方肌 - 上部、中部、下部；前锯肌；三角肌；冈下肌）和肩痛（11 点量表）在手臂抬高期间进行操作前后收集，并标准化为参考收缩。在基线和干预后 2-3 天使用宾夕法尼亚肩部评分 (Penn) 评估临床益处。

发现

在手臂上升过程中观察到肌肉活动显着增加 ( p  = 0.002)。使用向后逐步回归分析，手臂抬高期间前锯肌活动的特定增加解释了操作后 Penn 评分的改善 ( p  < 0.05)。

解释

胸椎推拿会立即增加神经肌肉驱动力。此外，肩胛骨运动的关键肌肉——前锯肌活动的增加与肩部临床结果的短期改善有关。