Do You Need to Train to Failure to Build Muscle?

You are deep into a hard set of squats, the bar drags on every rep, and a voice tells you to keep going until you cannot move it. Many lifters learned that a set only counts if it ends in failure. The research on this question has grown, and it points to a less punishing way to train for most healthy adults who lift.

The studies below report results as effect sizes. An effect size shows how far apart two groups ended up, measured against the normal spread of results. A value near 0 means little or no difference. Here, a plus sign favours training to failure and a minus sign favours stopping short.

What training to failure means

Researchers use more than one definition of failure. Momentary muscular failure is the point where you cannot lift the weight again despite full effort. Some studies use a looser end point, such as the lifter choosing to stop. In this guide, failure means momentary muscular failure unless we say otherwise.

Reps in reserve counts how many more reps you could have done before failure. Stop one rep short and you have 1 rep in reserve. Stop three reps short and you have 3 in reserve. It is a simple way to describe how hard a set was, and it is the scale the 2025 trial used.

What the research shows

In 2022, Jozo Grgic and colleagues combined 15 studies in the Journal of Sport and Health Science, all in young adults, both trained and untrained. They found no significant difference between failure and non-failure training for strength (effect size -0.09) or for muscle size (effect size 0.22). Their conclusion: training to muscle failure does not seem to be required for gains in strength and muscle size, and it does not seem to harm them either.

In Sports Medicine in 2023, Martin Refalo and colleagues reviewed 15 studies of muscle growth in adults of any age and training experience. In the 9 studies that compared failure with stopping short, using any definition of failure, they found a trivial advantage for failure (effect size 0.19). The total weight lifted and the relative load made no difference to that result. Most of those 9 studies used untrained participants. In the studies that used momentary muscular failure, the advantage was not significant.

The 0.19 result only just reached significance, and the authors said it should be interpreted with caution. The other 6 studies in the review compared velocity loss thresholds, a lab measure of how much bar speed drops during a set. From those, the authors suggested the link between closeness to failure and growth is not a straight line.

A 2025 randomised trial in Medicine and Science in Sports and Exercise, led by Thomas Hermann, assigned 42 young, resistance-trained men and women to train either to failure or with 2 reps in reserve. Both groups did a single set of each of 9 exercises, twice a week for 8 weeks. Strength and muscular endurance gains were similar. Several measures of muscle size tended to favour the failure group, though the authors described the absolute differences as generally modest.

There is a small caveat for experienced lifters. In the Grgic review, a subgroup of resistance-trained people showed a significant effect of training to failure on muscle size (effect size 0.15). That is about the same size as the Refalo result, which its authors called trivial.

Why many lifters stop short

In our view, if the strength and muscle results are close, the deciding factor is everything around the set. Sets to failure feel harder and tend to leave you more tired for the next session, and on a heavy squat, deadlift or bench press the final failing rep is where technique is most likely to slip. None of the studies here measured those costs directly. Leaving 1 to 3 reps in reserve keeps your positions sharp and lets you finish the session strong.

The Grgic review also found that in studies where the two groups did different amounts of total work, non-failure training gave significantly greater strength gains (effect size -0.32). In our view, part of that gap likely reflects the difference in work, not effort level alone, so treat it as a weak point in favour of stopping short.

How hard your sets need to be

Stopping short only works if you still train with real effort. In our view, the sweet spot for most working sets is 1 to 3 reps in reserve: you end the set knowing you had 1 to 3 reps left, not 5, and not 0.

Judging reps in reserve takes practice. In the Hermann trial, participants were more accurate at estimating reps in reserve on the bench press than on the squat, and their accuracy improved over the 8 weeks, mostly on the bench press. In our view, an occasional set to momentary failure on a machine exercise helps you learn where your limit is, so you place your other sets more accurately.

How to put it into practice

These steps are ours, built from the studies above.

Common mistakes

These are our views, based on the studies above.

• •Sandbagging, or stopping far too early. Leaving 5 or more reps in reserve on most sets is too little effort. The 2025 trial compared failure with stopping 2 reps short, which is still a hard set.
• •Taking every set of every exercise to failure. This piles up fatigue and tends to cost you quality sets later in the week.
• •Chasing soreness as proof of a good workout. Soreness is a poor guide to progress, and a session that leaves you less tired is not a worse one.

Frequently asked questions

The bottom line

A 2022 meta-analysis found that training to failure is not required for strength or muscle growth, and a 2023 meta-analysis found at most a trivial muscle growth advantage. In a programme of one set per exercise, a 2025 trial found similar strength gains with 2 reps in reserve. In our view, train with real effort, stop 1 to 3 reps short of failure, and add a little weight or a rep over time.

Related reading

• •How many sets a week build muscle
• •Rest between sets
• •Do you need heavy weights to build muscle
• •Muscle soreness and a good workout

Sources

• •Grgic J, Schoenfeld BJ, Orazem J, Sabol F. 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 2022. pubmed.ncbi.nlm.nih.gov/33497853
• •Refalo MC, Helms ER, Trexler ET, Hamilton DL, Fyfe JJ. Influence of Resistance Training Proximity-to-Failure on Skeletal Muscle Hypertrophy: A Systematic Review with Meta-analysis. Sports Medicine 2023. pubmed.ncbi.nlm.nih.gov/36334240
• •Hermann T, Mohan AE, Enes A, et al. Without Fail: Muscular Adaptations in Single-Set Resistance Training Performed to Failure or with Repetitions-in-Reserve. Medicine and Science in Sports and Exercise 2025. pubmed.ncbi.nlm.nih.gov/40249908