Diederichsen, L. P., Winther, A. K., Dyhre-Poulsen, P, Krogsgaard, M. R., & Norregaard, J. (2003). Changes in should muscle activity during experimentally induced pain. Medicine and Science in Sports and Exercise, 35(5), Supplement abstract 1563.

Healthy males (N = 7) were measured for muscle activity (wire electrodes in the supraspinatus and infraspinatus and surface electrodes at six other sites). Maximal voluntary contractions of shoulder dynamic abductions and external rotations were performed and EMG activity recorded. Ss were then given a hypertonic saline injection in the supraspinatus followed by a subacromial injection to induce pain. Movements were then repeated.

All muscles except the trapezius, showed higher EMG magnitude when in the pain condition. Pain was general rather than specific in location. When pain was induced subacromially, Ss performed external rotation with higher activity than when the pain was in the suprspinatus.

Implication. Pain has a strong influence on voluntary motor function of the shoulder muscles. When athletes perform with pain, effort will be higher and consequently, fatigue will occur quicker than without pain. There is little justification for performing with pain because performance will be compromised.

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