[Dynamic analysis of the shoulder girdle muscles during tracking movements in the scapular plane and in the sagittal plane--an electromyographic study].

Analyse were made of electromyograms from the upper trapezius, middle deltoideus, supraspinatus and infraspinatus during tracking movements in the scapular plane and the sagittal plane of ten males. The purpose was to determine electromyographically how these muscles act in various phases and speeds of the shoulder movements in those planes. The middle deltoideus and the supraspinatus showed significantly greater electrical activity with a shoulder motion in the scapular plane than in sagittal plane having a higher efficiency in the scapular plane. There was no change observed in the electrical activity of the infraspinatus, whatever the speed or direction of the shoulder movements was. The upper trapezius seemed to play an important role in the fast scapulohumeral rhythm. The middle deltoideus played a similar important role in the slow rhythm and the supraspinatus was important in both fast and slow rhythms.