Muscle activation during resistance exercise at 70% and 90% 1-repetition maximum in resistance-trained men

Introduction Muscle activation was investigated during resistance exercise with 2 relatively high-intensity loads. Methods Ten resistance-trained men performed the leg press exercise to repetition failure: a set at 70% of 1-repetition maximum (1RM) and a set at 90% of 1RM. Surface electromyography (EMG) was used to assess peak and mean muscle activation of the vastus lateralis, rectus femoris, and vastus medialis. Results Peak and mean EMG remained greater at 90% than 70% 1RM across all repetitions (P = 0.03 and P = 0.02, respectively). Main effects for trial were also significant for mean EMG activity of the final common repetitions (P = 0.03) favoring 90% 1RM; however, peak EMG activity was similar during the final common repetitions of the 70% and 90% 1RM sets. Conclusions Across all repetitions, 90% 1RM appears to produce greater muscle activation during the leg press exercise, but similar peak EMG was observed during the final common repetitions of each set. Muscle Nerve 56: 505–509, 2017