Electromyographic study of shoulder joint.

The abduction in the scapular plane and forward flexion of the arm were studied in ten subjects by electromyography combined with goniometry permitting simultaneous measurement of arm and glenohumeral angles. The "integrated" electromyograms from six should girdle muscles plotted against the arm angle were submitted to variance analysis for pattern discrimination. The progression of electromyographic activities in these muscles was discriminable with errors ranging from 0.0 to 26.3 percent and could be classified in several categories. Their relationship with functional mechanism to the abduction movement was not necessarily constant, but accelerated just before the maximum elevation.