Objectives To compare muscle recruitment, maximal force, and rate of force development changes following different resistance exercise protocols with a constant volume-load. Design Within-subjects randomized crossover trial. Methods Fourteen (n = 14) resistance trained male participants completed three different resistance exercise protocols involving 20 squat repetitions, prescribed at 80% of 1-repetition-maximum. Protocol A consisted of 5 sets of 4 repetitions with 3 min inter-set rest intervals, protocol B was 5 sets of 4 repetitions with 20 s inter-set rest intervals, and the rest-pause method was an initial set to failure with subsequent sets performed with a 20 s inter-set rest interval. Maximal squat isometric force output and rate of force development (RFD) were measured before, immediately upon completion (IP), and 5 min (5P) following each protocol. Muscle activity from 6 different thigh and hip muscles was measured with surface electromyography (EMG) at each time point, and during every squat repetition. Results Participants completed the rest-pause method in 2.1 ± 0.4 sets, with a total protocol duration of 103 s compared to 140 s and 780 s for protocols B and A, respectively. All protocols elicited similar decreases (p < 0.05) in maximal force and RFD at IP, with full recovery at 5P. Increased motor unit recruitment was observed during the rest-pause method compared to both protocols A and B for all muscles measured (p < 0.05). Conclusions As a result of the increased EMG during exercise and no greater post-exercise fatigue, it was concluded that the rest-pause method may be an efficacious training method for resistance-trained individuals.
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