“Training close to failure is the key to building muscle.”
Ending sets close to failure is a main driver of muscle growth, especially with light weights, but going all the way to failure is not needed.
Effort is one of the biggest things you control when you want more muscle. Sets should feel truly hard by the end, especially with lighter weights, but you do not need to grind every set until you cannot move the weight. Doing enough hard sets each week, week after week, also matters. Whether you have to go all the way to failure is covered in our card "You have to train to failure to build muscle."
In your next workout, end each set when you could do only one to three more good reps.
A meta-analysis of training studies found that muscle growth rose as sets ended closer to failure, and a controlled trial showed that light sets stopped far short of failure built little muscle. Confidence is moderate because the studies are small and mostly in young men, effort was often estimated, and heavy sets stopped well short of failure still built muscle in one trial.
Ending sets close to failure is a main driver of muscle growth, especially with light weights, but going all the way to failure is not needed. A 2024 analysis of training studies found that muscle growth increased as sets ended closer to the point where no more reps were possible. In an 8-week trial of 25 untrained men, light sets taken to failure grew the thigh muscle by about 8 percent, while light sets stopped at about half the possible reps grew it by about 3 percent, a change too small to rule out chance.
Effort is not the whole story. In the same trial, heavy sets grew the muscle by about 8 percent whether people went to failure or stopped at about half the reps they could do, so with heavy weights, stopping several reps short still worked. Going all the way to failure adds little: an 8-week trial in 18 trained adults found the same thigh muscle growth when sets went to failure or stopped 1 to 2 reps short. How many hard sets you do each week also drives growth, as shown in a 67-study analysis of training volume. US activity guidelines advise working muscles "to the point where it's hard to do another repetition without help."
How close to failure you need to go depends on the weight. With light weights, the last few reps before failure seem to be where most of the growth comes from. With heavy weights, sets stopped at about half the possible reps built muscle as well as sets taken to failure in one controlled trial.
- Robinson ZP, Pelland JC, Remmert JF, Refalo MC, Jukic I, Steele J, Zourdos MC. Exploring the Dose-Response Relationship Between Estimated Resistance Training Proximity to Failure, Strength Gain, and Muscle Hypertrophy: A Series of Meta-Regressions. Sports Medicine. 2024;54(9):2209-2231. DOI: 10.1007/s40279-024-02069-2. PMID: 38970765
- Lasevicius T, Schoenfeld BJ, Silva-Batista C, Barros TS, Aihara AY, Brendon H, Longo AR, Tricoli V, Peres BA, Teixeira EL. Muscle Failure Promotes Greater Muscle Hypertrophy in Low-Load but Not in High-Load Resistance Training. Journal of Strength and Conditioning Research. 2022;36(2):346-351. DOI: 10.1519/JSC.0000000000003454. PMID: 31895290
- Refalo MC, Helms ER, Robinson ZP, Hamilton DL, Fyfe JJ. Similar muscle hypertrophy following eight weeks of resistance training to momentary muscular failure or with repetitions-in-reserve in resistance-trained individuals. Journal of Sports Sciences. 2024;42(1):85-101. DOI: 10.1080/02640414.2024.2321021. PMID: 38393985
- Pelland JC, Remmert JF, Robinson ZP, Hinson SR, Zourdos MC. The Resistance Training Dose Response: Meta-Regressions Exploring the Effects of Weekly Volume and Frequency on Muscle Hypertrophy and Strength Gains. Sports Medicine. 2026;56(2):481-505. DOI: 10.1007/s40279-025-02344-w. PMID: 41343037
- US Centers for Disease Control and Prevention. What Counts as Physical Activity for Adults. December 6, 2023