“Train harder” is not a programme. The useful question is whether a set must reach momentary muscular failure—the point at which another concentric repetition cannot be completed with the intended technique—to stimulate strength or muscle growth.
Failure is not necessary for strength or hypertrophy. For muscle growth, stopping closer to failure may improve the stimulus, but the exact dose-response remains uncertain. For strength, the available pooled evidence shows little relationship between estimated repetitions in reserve and gains.
What the pooled studies found
A 2022 systematic review and meta-analysis combined 15 studies, all in young adults. It found no significant overall difference between failure and non-failure training for strength or hypertrophy. When training volume was not equal, non-failure training favoured strength; in resistance-trained participants, a small hypertrophy effect favoured failure.
A separate 2023 systematic review with 15 studies found no evidence that momentary failure was superior for hypertrophy. Definitions of “failure” varied, which is not a minor problem: set failure, technical failure, velocity-loss thresholds and true momentary failure are different exposures.
A 2024 series of exploratory meta-regressions produced a more nuanced signal. Strength gains were similar across a wide range of estimated repetitions in reserve, while muscle growth tended to increase as sets ended closer to failure. However, the researchers had to estimate repetitions in reserve from study descriptions, model fit was only modest, and the exact relationship remains unclear.
Reported fact versus practical inference
Reported fact: pooled comparisons do not show that every set must reach momentary failure. ShreddedAF inference: most lifters can make hard, technically controlled sets the base of hypertrophy training and reserve true failure for exercises and situations where fatigue does not create an unacceptable technique or safety cost.
That is a programming principle, not a proven universal “two reps in reserve” law. Rep accuracy changes with experience, exercise selection, load, motivation and accumulated fatigue.
Population and evidence limits
The evidence is dominated by healthy younger adults, short interventions and relatively small samples. Women, older adults, adolescents, highly trained strength athletes and people returning from injury are under-represented. The literature also measures muscle size with different methods and often equates—or fails to equate—training volume in ways that change the comparison.
References
- Grgic J et al. Failure versus non-failure training for strength and hypertrophy: systematic review and meta-analysis; 15 studies, young adults. PubMed 33497853.
- Refalo MC et al. Proximity to failure and skeletal-muscle hypertrophy: systematic review with meta-analysis; 15 studies in healthy adults. PubMed 36334240.
- Robinson ZP et al. Estimated proximity to failure, strength and hypertrophy: exploratory multilevel meta-regressions. PubMed 38970765.