A non-invasive procedure involving the detection, recording and interpretation of the electric activity of groups of muscles at rest and during activity. The procedure is performed using a single or an array of electrodes placed on the skin surface over the muscles to be tested. SEMG is occasionally used to diagnose neuromuscular disorders, determine the need for surgery in individuals with lower back pain, and assist in evaluating the prognosis of disorders involving muscle lesions. The technology has also been utilized to monitor the effects of rehabilitation programs and evaluate muscular function in occupational and sports programs.