Upper body muscle activation during low-versus high-load resistance exercise in the bench press

OBJECTIVE: The purpose of this study was to compare activation of the upper body musculature during the barbell bench press at varying training intensities. METHODS: Twelve young, resistance-trained men performed sets of the bench press to momentary muscular failure with two different loads: a high-load (HIGH) set at 80% of 1RM and a low-load (LOW) set at 50% 1RM. Exercise order was counterbalanced so that half the subjects performed the LOW condition first and the other half performed the HIGH first. Surface electromyography (EMG) was used to assess mean, peak, and iEMG muscle activation of the anterior deltoid, triceps brachii, and sternal and clavicular heads of the pectoralis major. RESULTS: The main effects for trials were significant for mean EMG (p > 0.001) and iEMG matched (p > 0.001) favoring HIGH and iEMG total favoring LOW(p = 0.001) across all muscle groups in both conditions with varying effect sizes. All other main effects and interactions were not statistically significant. CONCLUSION: Despite similarities in peak EMG amplitude, the greater results for mean and iEMG matched in HIGH suggests that heavier loads may produce greater muscle activation.