The effect of pain reduction on perceived tension and EMG-recorded trapezius muscle activity in workers with shoulder and neck pain.

The study was initiated to evaluate the effect of pain-reducing therapies on factors previously associated with work-related shoulder and neck pain, namely increased muscle activity in the upper trapezius and perceived general tension. Thirty-three women in three groups were assessed before and after an intervention period and by questionnaire 6 months later. The purpose of this study was primarily to investigate associations between upper trapezius muscle activity, perceived general tension and pain, and secondly, to compare effects of individually based physiotherapy and group exercise for workers with shoulder and neck myalgia. All three groups reported a significant alleviation of pain and perceived general tension, while the electromyographically (EMG) recorded upper trapezius muscle activity level remained unchanged or increased. Improvements were similar in all three treatment groups, but individual-based therapies were rated more beneficial on subjective measures. Significant correlation was found between pain and perceived general tension (r = 0.66, p <0.01), while there was no correlation between pain or perceived general tension and recorded muscle activity.