Muscle Failure Promotes Greater Muscle Hypertrophy in Low-Load but Not in High-Load Resistance Training

Lasevicius, T, Schoenfeld, BJ, Silva-Batista, C, Barros, TdS, Aihara, AY, Brendon, H, Longo, AR, Tricoli, V, Peres, BdA, and Teixeira, EL. Muscle failure promotes greater muscle hypertrophy in low-load but not in high-load resistance training. J Strength Cond Res 36(2): 346-351, 2022-The purpose of this study was to investigate the effects of an 8-week resistance training program at low and high loads performed with and without achieving muscle failure on muscle strength and hypertrophy. Twenty-five untrained men participated in the 8-week study. Each lower limb was allocated to 1 of 4 unilateral knee extension protocols: repetitions to failure with low load (LL-RF; similar to 34.4 repetitions); repetitions to failure with high load (HL-RF; similar to 12.4 repetitions); repetitions not to failure with low load (LL-RNF; similar to 19.6 repetitions); and repetitions not to failure with high load (HL-RNF; similar to 6.7 repetitions). All conditions performed 3 sets with total training volume equated between conditions. The HL-RF and HL-RNF protocols used a load corresponding to 80% 1 repetition maximum (RM), while LL-RF and LL-RNF trained at 30% 1RM. Muscle strength (1RM) and quadriceps cross-sectional area (CSA) were assessed before and after intervention. Results showed that 1RM changes were significantly higher for HL-RF (33.8%, effect size [ES]: 1.24) and HL-RNF (33.4%, ES: 1.25) in the post-test when compared with the LL-RF and LL-RNF protocols (17.7%, ES: 0.82 and 15.8%, ES: 0.89, respectively). Quadriceps CSA increased significantly for HL-RF (8.1%, ES: 0.57), HL-RNF (7.7%, ES: 0.60), and LL-RF (7.8%, ES: 0.45), whereas no significant changes were observed in the LL-RNF (2.8%, ES: 0.15). We conclude that when training with low loads, training with a high level of effort seems to have greater importance than total training volume in the accretion of muscle mass, whereas for high load training, muscle failure does not promote any additional benefits. Consistent with previous research, muscle strength gains are superior when using heavier loads.

Automated summary

This study investigated the effects of muscle failure on muscle strength and hypertrophy in low-load and high-load resistance training. The results showed that training with a high level of effort seems to have greater importance than total training volume in promoting muscle hypertrophy in low-load training, while muscle failure does not provide any additional benefits in high-load training. Muscle strength gains are superior when using heavier loads.