Do You Need to Train to Failure to Build Muscle?

Training to failure has a clean definition: you keep going until you cannot complete another repetition with acceptable technique. It also has an intuitive appeal. If a set is supposed to stimulate muscle, taking it as far as possible feels like it should be better.

The evidence is more nuanced. Failure can work, but it is not a requirement for building muscle or strength. What seems to matter more for hypertrophy is that working sets are sufficiently challenging. Going all the way to failure may add stimulus in some situations, but it also adds fatigue—and the extra benefit is often small or uncertain.

Failure and effort are not the same thing

A set can be hard without ending at failure. Coaches often describe this with repetitions in reserve, or RIR: an estimate of how many clean repetitions you could still perform when you stop.

Zero RIR is essentially failure. One RIR means you believe you had one more good rep. Three RIR means you stopped with roughly three reps left. This distinction matters because “not training to failure” can mean anything from stopping one rep early to stopping while the set is still easy.

That is why the useful question is not simply failure versus no failure. It is how close to failure you need to get for the goal you care about—and what fatigue you pay to get there.

The newest meta-analysis does not show a hypertrophy advantage for failure

A 2026 systematic review and meta-analysis pooled 20 studies with 556 healthy adults comparing resistance training performed to failure with training stopped before failure. The researchers found no significant difference in muscle hypertrophy, muscular endurance, power, or isometric strength. Dynamic strength showed a small advantage for non-failure training.

That result is consistent with an earlier 2022 meta-analysis of 15 studies. Across the full dataset, training to failure did not significantly outperform non-failure training for strength or hypertrophy. In trained participants, there was a small hypertrophy signal favoring failure, but the broader conclusion was that failure was not required.

These analyses have an important limitation: studies define and prescribe “non-failure” in different ways. Some groups stop very close to failure; others stop much farther away. Pooling them together can blur the actual dose-response relationship.

For muscle growth, getting close probably matters more than crossing the line

A 2024 meta-regression tried to address that problem by estimating proximity to failure continuously rather than dividing training into two categories. Strength gains were similar across a wide range of estimated RIR, while muscle growth tended to improve as sets ended closer to failure.

That does not prove there is a universal “perfect” RIR. The authors emphasized that proximity was estimated from study descriptions, the models had only modest fit, and the exact relationship remains uncertain. But the direction is useful: for hypertrophy, a set that ends with five or six easy repetitions left is probably not equivalent to one that ends just short of failure.

A separate 2023 systematic review reached a compatible conclusion. There was no evidence that momentary muscular failure itself was superior to non-failure training for hypertrophy. In other words, getting sufficiently close may capture much of the benefit without making the final failed rep mandatory.

A direct trial shows the fatigue tradeoff

In a 2024 study, 18 resistance-trained men and women trained their legs for eight weeks. One leg was taken to momentary muscular failure, while the other stopped at approximately two RIR on leg press and one RIR on leg extension. Quadriceps growth was essentially identical between conditions, while the failure condition produced greater repetition loss and lifting-velocity loss.

An acute crossover study makes the fatigue difference even clearer. Twenty-four trained adults performed six bench-press sets to failure, one RIR, or three RIR. Immediately afterward, lifting velocity fell by about 25% after failure training, 13% after one RIR, and 8% after three RIR. Discomfort, exertion, soreness, and perceived recovery also worsened as sets moved closer to failure.

That does not make fatigue bad. Fatigue is part of training. The issue is whether the last repetition or two creates enough additional adaptation to justify the extra recovery cost, especially when you still have more sets, exercises, or training days to complete.

There are situations where failure may be more useful

The strongest argument for failure may be when training volume is deliberately very low. A 2025 randomized trial assigned 42 trained adults to a minimalist program: one set of nine exercises, twice per week, either to failure or stopping at two RIR. Both groups improved, and strength and local muscular endurance were similar, but several hypertrophy measures modestly tended to favor the failure group.

That makes physiological sense as a practical hypothesis: if you only perform one working set, squeezing more stimulus from that set may matter more than it does when several hard sets are already planned. It is not proof that every low-volume set must reach failure, but it is a reason not to turn “never train to failure” into a rule either.

RIR is useful, but it is still an estimate

Stopping “two reps short” only works if you can estimate two reps short reasonably well. Even trained lifters are imperfect at this. In a 2024 bench-press study, objective lifting-velocity measures were more accurate than subjective RIR estimates in several early-set and lower-load conditions.

Experience helps, and occasional calibration can help too. On a safe exercise, taking a set to true technical failure from time to time can teach you what zero RIR actually feels like. The point is not to fail constantly; it is to make your non-failure estimates more honest.

A practical way to use the evidence

• For most hypertrophy work, make the set genuinely hard. A practical default is often to finish with roughly one to three clean repetitions in reserve, recognizing that this is a coaching range rather than a biologically proven universal optimum.
• Do not confuse discomfort with effectiveness. The burning final reps are memorable, but current evidence does not show that reaching failure on every set is necessary for growth.
• Be more selective with failure when fatigue is expensive. If you still have several demanding sets or exercises ahead, stopping just short can preserve more performance for the rest of the session.
• Failure is easier to deploy on exercises with a simple, controlled endpoint. A machine curl, leg extension, or cable movement generally makes it easier to stop when technique breaks down than a complex free-weight lift. This is a practical programming inference, not evidence that one exercise category is universally safer.
• If your program is intentionally minimal, failure becomes more defensible. With only one working set, the possible small extra hypertrophy stimulus may be worth the fatigue.
• For strength, leave room for high-quality repetitions. The current literature does not show a need to fail, and the 2026 meta-analysis found a small dynamic-strength advantage for non-failure training.

The bottom line

You do not need to train to failure to build muscle. You do need to train hard enough that the working set is meaningfully challenging.

For most people, the highest-value distinction is not “failure or no failure.” It is easy sets versus hard sets, and useful fatigue versus unnecessary fatigue. Get reasonably close to failure on the sets that matter, use actual failure selectively, and judge the approach by whether you can keep accumulating high-quality training over weeks and months.

This Field Note is for general educational purposes and is not individualized exercise or medical advice. People with injuries, cardiovascular limitations, or other medical conditions that affect exercise tolerance should individualize resistance training with an appropriate clinician or qualified professional.

Sources and further reading

1. Wu S et al. Effects of resistance training performed to repetition non-failure on exercise performance in healthy adults: a systematic review and meta-analysis. BMC Sports Sci Med Rehabil. 2026.
2. Grgic J et al. Effects of resistance training performed to repetition failure or non-failure on muscular strength and hypertrophy: a systematic review and meta-analysis. J Sport Health Sci. 2022.
3. Refalo MC et al. Influence of Resistance Training Proximity-to-Failure on Skeletal Muscle Hypertrophy: A Systematic Review with Meta-analysis. Sports Med. 2023.
4. Robinson ZP et al. Exploring the Dose-Response Relationship Between Estimated Resistance Training Proximity to Failure, Strength Gain, and Muscle Hypertrophy: A Series of Meta-Regressions. Sports Med. 2024.
5. Refalo MC et al. Similar muscle hypertrophy following eight weeks of resistance training to momentary muscular failure or with repetitions-in-reserve in resistance-trained individuals. J Sports Sci. 2024.
6. Refalo MC et al. Influence of Resistance Training Proximity-to-Failure, Determined by Repetitions-in-Reserve, on Neuromuscular Fatigue in Resistance-Trained Males and Females. Sports Med Open. 2023.
7. Hermann T et al. Without Fail: Muscular Adaptations in Single-Set Resistance Training Performed to Failure or with Repetitions-in-Reserve. Med Sci Sports Exerc. 2025.
8. Hickmott LM et al. A Comparison of Subjective Estimations and Objective Velocities at Quantifying Proximity to Failure for the Bench Press in Resistance-Trained Men and Women. J Strength Cond Res. 2024.