Nóbrega, SR, Ugrinowitsch, C, Pintanel, L, Barcelos, C, and Libardi, CA. Effect of resistance training to muscle failure vs. volitional interruption at high- and low-intensities on muscle mass and strength. J Strength Cond Res 32(1): 162–169, 2018—The purpose of this study was to investigate the effects of resistance training (RT) at high- and low-intensities performed to muscle failure or volitional interruption on muscle strength, cross-sectional area (CSA), pennation angle (PA), and muscle activation. Thirty-two untrained men participated in the study. Each leg was allocated in 1 of 4 unilateral RT protocols: RT to failure at high and low intensities, and RT to volitional interruption (repetitions performed to the point in which participants voluntarily interrupted the exercise) at high (HIRT-V) and low (LIRT-V) intensities. Muscle strength (1 repetition maximum [1RM]), CSA, PA, and muscle activation by amplitude of the electromyography (EMG) signal were assessed before (Pre), after 6 (6W), and 12 (12W) weeks. 1RM increased similarly after 6W (range: 15.8–18.9%, effective size [ES]: 0.41–0.58) and 12W (range: 25.6–33.6%, ES: 0.64–0.98) for all protocols. All protocols were similarly effective in increasing CSA after 6W (range: 3.0–4.6%, ES: 0.10–0.24) and 12W (range: 6.1–7.5%, ES: 0.22–0.26). PA increased after 6W (∼3.5) and 12W (∼9%; main time effect, p < 0.0001), with no differences between protocols. EMG values were significantly higher for the high-intensity protocols at all times (main intensity effect, p < 0.0001). In conclusion, both HIRT-V and LIRT-V are equally effective in increasing muscle mass, strength, and PA when compared with RT performed to muscle failure.
1Laboratory of Neuromuscular Adaptations to Resistance Training, Department of Physical Education, Federal University of São Carlos, São Carlos, Brazil; and
2Department of Sport, School of Physical Education and Sport, University of São Paulo–USP, São Paulo, Brazil
Address correspondence to Dr. Cleiton A. Libardi, firstname.lastname@example.org.