Fifteen male college students participated in a competitive isometric exercise involving elbow flexion. The men were grouped into five teams each consisting of three men. A prize of 25 was offered to the team which maintained the greatest force for the longest time. Prior to the competitive session each subject practiced individually on the apparatus for eight sessions. The men were randomly assigned to the teams on the day of the competition. During each session, continuous EMG recordings were made on the biceps muscle of the right arm. Training significantly improved both strength and endurance while reducing the average EMG amplitude. The highest level of performance for the group was obtained in the final training session. When team competition was introduced, there was a decrease in endurance and an increase in EMG amplitude. It was concluded that training improved muscular strength and endurance by increasing the efficiency of muscle utilization. Competition, even with a partially trained skill, was considered a stressful situation that produced an overexpenditure of muscle activity and a resulting decrease in performance.