Do you have to train to failure to grow?

What the meta-analyses say about training close to muscular failure, with the references.

~3 min read·last reviewed ·4 sources linked

From the same series: how many sets per muscle? · how long to rest between sets? · how many times per week? · the whole series

Short answer: you don't have to reach failure. Strength improves just as much stopping well short, and in head-to-head comparisons the hypertrophy advantage of failure is trivial. What the finest evidence does suggest: for muscle size, getting close to failure — about 0–3 reps in reserve — returns a bit more than staying far away.

For hypertrophy
RIR 0–3
approaching failure improves growth gradually, with no magic threshold1
Failure vs non-failure
ES 0.19
the direct-comparison advantage of failure: trivial, with zero inside the interval2
For strength
≈ equal
reaching failure adds no strength; with volume not equated, it even subtracts13

§1What is training to failure, and what is RIR?

Training to failure means ending the set when no further rep is possible with technique intact. RIR (reps in reserve) measures the opposite: how many reps you had left when you stopped. A set at RIR 2 ends two reps before failure; a set to failure is RIR 0. The scale was formalised by Helms, Cronin, Storey and Zourdos in 2016 and is now the standard way to log effort.4

§2What did each study find?

The three main syntheses on proximity to failure, in order of publication.
StudyWhat it comparedResult
Grgic 2022315 studiesStrength: no difference (ES −0.09). Hypertrophy: no significant difference (ES 0.22); in trained subjects, a small benefit of failure (ES 0.15).
Refalo 20232failure vs non-failureTrivial hypertrophy advantage for failure (ES 0.19; CI 0.00–0.37); with strict momentary failure, nothing conclusive.
Robinson 20241RIR as a continuumStrength: flat across RIR. Hypertrophy: gradual improvement as sets approach failure, with no identifiable threshold.
How to read these numbers: a meta-analysis pools and re-analyses every published study on a question. ES and SMD measure effect size — how much real difference there is between groups: 0.2 is considered small, 0.5 medium. The CI (confidence interval) is the margin of error: if it includes zero, the difference may not exist. An RCT is a trial with randomly assigned groups.
What we know
  • For strength, RIR barely matters: gains are similar across a wide range of effort.1
  • For hypertrophy, training closer to failure returns more than staying far from it, gradually.1
  • Strict failure adds nothing demonstrable over stopping 1–2 reps short.2
What we don't
  • How close is "close enough": there is no threshold, only a continuum with uncertainty.1
  • The long-term recovery cost of systematic failure training is poorly measured in long studies.

§3How do you apply it?

The practical reading is simple: train close to failure, not necessarily to it. The hard sets that count toward your weekly volume are the ones ending 0–3 reps from failure; below that effort, a set counts on paper but doesn't push the same. Logging RIR next to your reps — or at least being honest about it — is what turns "8 sets" into 8 comparable sets.

§4References

  1. Robinson, Z. P., Pelland, J. C., Remmert, J. F., Refalo, M. C., Jukic, I., Steele, J., & Zourdos, M. C. (2024). Exploring the dose-response relationship between estimated resistance training proximity to failure, strength gain, and muscle hypertrophy: a series of meta-regressions. Sports Medicine, 54(9), 2209–2231. doi.org/10.1007/s40279-024-02069-2
  2. Refalo, M. C., Helms, E. R., Trexler, E. T., Hamilton, D. L., & Fyfe, J. J. (2023). Influence of resistance training proximity-to-failure on skeletal muscle hypertrophy: a systematic review with meta-analysis. Sports Medicine, 53(3), 649–665. doi.org/10.1007/s40279-022-01784-y
  3. Grgic, J., Schoenfeld, B. J., Orazem, J., & Sabol, F. (2022). Effects of resistance training performed to repetition failure or non-failure on muscular strength and hypertrophy: a systematic review and meta-analysis. Journal of Sport and Health Science, 11(2), 202–211. doi.org/10.1016/j.jshs.2021.01.007
  4. Helms, E. R., Cronin, J., Storey, A., & Zourdos, M. C. (2016). Application of the repetitions in reserve-based rating of perceived exertion scale for resistance training. Strength and Conditioning Journal, 38(4), 42–49. doi.org/10.1519/SSC.0000000000000218