THE NORMAL AND THE PAINFUL SHOULDERS DURING THE BREASTSTROKE - ELECTROMYOGRAPHIC AND CINEMATOGRAPHIC ANALYSIS OF 12 MUSCLES

The purpose of this study was to describe and compare electrical activ ity patterns in 12 shoulder muscles during the breaststroke in 25 comp etitive swimmers who had normal shoulders and in 14 who had painful sh oulders while they performed this stroke in a pool. The electromyograp hic analysis was synchronized with high-speed cinematography to discer n phases of the breaststroke. Means, standard deviations, and t-tests were done for each phase. The differences in muscle activity between t he two groups of swimmers demonstrated an increase in the internal rot ators in the group with painful shoulders. They also demonstrated a de crease in the teres minor, supraspinatus, and the upper trapezius musc les. These factors increase the risk of impingement. Both the serratus anterior and teres minor muscles in the swimmers with normal shoulder s consistently fired at or above 15% manual muscle test throughout the breaststroke cycle and were thus subject to fatigue. Based on these r esults, exercises for the breaststroke swimmer should be directed towa rd endurance training of the serratus anterior and teres minor muscles while balancing the internal and external rotators of the shoulder as well as the deltoid and supraspinatus muscles.