2015). Comparison of Varying Intensities on Activation and Fatigue of Muscle, and Number of Repetitions during Bench Press in Trained and Untrained Men. Exercise Science, 24(4): 399-405. PURPOSE: This study tested the hypothesis that low-intensity resistance exercise would not be different in activation and fatigue of muscle and number of repetitions between trained and untrained men, but high-intensity resistance exercise would more decrease muscle activity, increase muscle fatigue and lower

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... mber of repetitions in the untrained men when compared with those in the trained men. METHODS: Eight trained males (TG) and 8 healthy untrained males (UTG) participated in this study. TG had undertaken a continual, resistance weight training program at least twice a week for longer than 6 months using bench press exercises. UTG had not been previously involved in a formal resistance weight training program over the last year. All subjects were tested for 1RM strength, and then performed maximal number of repetitions at 3 different intensities (60, 80, and 90% of 1RM) during bench press. EMG signals were recorded from the pectoralis major, deltoid anterior, and triceps brachii for maximal voluntary contraction (%MVC) and median frequency (MDF). RESULTS: %MVC of pectoralis major was significantly higher at 60 (p=0.010), 70 (p=0.039) and 85% (p=0.000) of 1RM in the UTG than the TG. Number of repetitions was significantly lower with 3 sets (p=0.027) at the 60% of 1RM and, 2 (p=0.012) and 3 sets (p=0.049) at the 70% of 1RM in the UTG than the TG. However, no significant changes were found in %MVC of anterior deltoid and triceps brachii and MDF of pectoralis major, anterior deltoid and triceps brachii. CONCLUSIONS: These results did not support the hypothesis, and differences in activation and fatigue of muscle between the trained and untrained men were important in number of repetitions and recruitment ratio of agonist and synergist rather than exercise intensity.