The normal shoulder during freestyle swimming: An electromyographic and cinematographic analysis of twelve muscles

Abstract

The shoulder in swimming is subjected to multiple factors that can lead to a high injury rate. To prevent injury, one must understand the biomechanics of swim ming. This paper describes the electromyographic and cinematographic findings of 12 shoulder muscles in competitive swimmers without shoulder pain. The re sults show the three heads of the deltoid and the supraspinatus functioning in synchrony to place the arm at hand entry and exit, the rhomboids and upper trapezius to position the scapula for the arm, the pec toralis major and latissimus dorsi to propel the body, the subscapularis and serratus anterior as muscles with constant muscle activity, the teres minor functioning with the pectoralis major, and the infraspinatus active only to externally rotate the arm at midrecovery. This information is important to design optimal preventative and rehabilitative exercise programs.