Electromyographic activity and applied load during shoulder rehabilitation exercises using elastic resistance.

Abstract

Muscle activity (measured by electromyography) and applied load were measured during seven shoulder rehabilitation exercises done with an elastic resistance device. Nineteen men with no shoulder abnormalities performed seven exercises: external and internal rotation, forward punch, shoulder shrug, and seated rowing with a narrow, middle, and wide grip. Qualitative video (60 Hz) was synchronized with the electromyography data from eight muscles (2000 Hz). Fine-wire intramuscular electrodes were inserted into the supraspinatus and subscapularis muscles, and surface electrodes were placed over the anterior deltoid, infraspinatus, pectoralis major, latissimus dorsi, serratus anterior, and trapezius muscles. Ten trials per subject were analyzed for average and peak amplitude, and the results were expressed as a percentage of maximum voluntary contractions. The peak loads for all exercises ranged from 21 to 54 N. The muscle activity patterns suggest that these shoulder rehabilitation exercises incorporating elastic resistance, controlled movements, and low initial loading effectively target the rotator cuff and supporting musculature and are appropriate for postinjury and postoperative patients.