This systematic review and meta-analysis aimed to compare the effects of resistance training (RT) performed to non-failure versus failure on muscular strength, hypertrophy, endurance, and power in healthy adults. We searched four databases (PubMed, Web of Science, SPORTDiscus, and MEDLINE). Randomized controlled trials comparing RT performed to non-failure and failure were included. Outcomes included muscular strength, hypertrophy, endurance, and power. Random-effects meta-analyses were performed to calculate standardized mean differences (SMD) with 95% confidence intervals (CI). A total of 20 studies with 556 participants were included. The results indicated non-failure training superior to failure training in terms of dynamic strength (SMD pooled = 0.24, 95% CI: 0.06 to 0.42, p = 0.01). However, no significant effects were observed for isometric strength, muscular hypertrophy, muscular endurance, and muscular power. Subgroup analysis revealed that participant characteristics, training volume, training method, and training duration were moderating variables influencing training effects. These findings indicate that resistance training performed to non-failure appears to be as effective as training to failure for most neuromuscular adaptations and may provide a small advantage for dynamic strength development. These findings suggest that reaching muscular failure is not necessary to maximize resistance training adaptations. Future research should explore the long-term physiological and neuromuscular adaptations associated with non-failure training across different populations, training statuses, and sport events.
Wu et al. (Mon,) studied this question.