This study was conducted to determine the activity levels of the Pectoralis major, Brachioradialis, Latissimus dorsi and Rectus during forward and backward strokes in tennis. The subjects were five male college tennis players. Integrated electromyograms (integrated EMG) were obtained from an analysis of the results of rectified electromyography performed on the above four muscles. The integrated EMG were recorded for each subject during isometric voluntary contraction for each muscle. The relative muscle activity level was that determined during forward and backward strokes in tennis. The higher muscle activity levels were obtained from the Rectus and Brachioradialis in the forward stroke, and from the Brachioradialis and Pectoralis major in the backward stroke
