I evaluated the contractions of the muscles of the lower extremities during baseball pitching using video imaging and simultaneous surface EMG. The subjects were 10 members of a high school baseball club and, for contrast, 10 students without any baseball club experience. I divided their pitching movements into two phases determined with respect to the landing of the non-pivot leg. The EMG signal intensities over the 2 seconds prior to landing, and over the 2 seconds after landing, were then integrated to give an EMG value to each phase. I then computed this value as the % MMT. The abductor and adductor of the hip muscles of both lower extremities in the players were strongly contracted, especially the adductor. This finding was consistent with the observation that pitching tends to lead to adductor muscle disorders. Strengthening the adductor and its antagonist abductor can therefore directly influence the capability for pitching, and can reduce the risk for the adductor disorders.