Training to Failure: Benefits, Fatigue and When to Stop a Set

Training to failure means continuing a set until you cannot complete another repetition under the exercise’s specified conditions despite trying.

That is different from stopping because the set feels uncomfortable, and also different from continuing indefinitely by changing technique, shortening the movement or receiving assistance.

Failure is a training variable. It is neither mandatory for every productive set nor automatically harmful whenever it occurs.

Muscular failure and technique breakdown

In practice, you need an agreed definition of a repetition. A strict repetition and a shorter repetition completed with substantial momentum are not the same task.

If your intended technique breaks down before you can no longer move the load at all, ending the set can be the sensible decision. You do not need to abandon the exercise’s boundaries to demonstrate sufficient effort.

For a bench press, being unable to press the bar is also a safety problem unless the equipment and spotting arrangement are prepared. See the bench-press guide before attempting demanding sets.

Do you need failure for muscle growth?

An eight-week study in resistance-trained participants compared legs trained to failure with legs trained at approximately one or two repetitions in reserve, depending on the exercise. Average quadriceps growth was similar, while failure produced more acute fatigue.¹

That supports the usefulness of hard sets stopped just short of failure. It does not establish that stopping arbitrarily far from failure produces the same result, or that every muscle and training program responds identically.

A separate randomized study of single-set routines found improvements with both failure and two-RIR training. Some muscle-growth measures tended to favor failure, although the differences were generally modest; strength and muscular-endurance improvements were similar.²

The practical conclusion is more nuanced than either “always reach failure” or “failure can never help.” The number of sets, exercises and muscles being trained affects the decision.

What is the fatigue tradeoff?

In a randomized crossover experiment using bench-press sets, reaching failure caused greater short-term reductions in lifting velocity and less favorable fatigue-related ratings than stopping with repetitions remaining.³

Acute fatigue is not the same thing as long-term overtraining, permanent nervous-system damage or proof that a program will fail. It is a cost to consider when deciding how much demanding work to include and how to distribute it.

A strategy that makes the first set maximally exhausting may also change what you can accomplish in later sets or exercises.

Repetitions in reserve

RIR describes your estimate of how many more repetitions were possible with the intended technique. Leaving one or two repetitions in reserve means ending a hard set before a repetition actually fails.

The estimate is imperfect, especially when you are unfamiliar with the movement. See training intensity for how load, effort and RIR differ.

You can improve your understanding of effort without taking every exercise to its limit. A stable machine or a simple, easily stopped movement may offer a more manageable setting than a technically complex lift with no safety support.

When might failure be useful?

It can be one way to make a limited amount of training sufficiently demanding, or an occasional tool for understanding your effort estimates. It may fit better on selected sets than across every exercise in a session.

That is a programming choice, not a requirement to prove commitment. Someone practicing a new movement, managing fatigue or following rehabilitation instructions may have a good reason to stop earlier.

When should you stop regardless of the plan?

Stop if the equipment becomes unsafe, you lose control of the load or you develop symptoms that are not ordinary muscular effort. Sharp or worsening pain, dizziness or a sudden loss of function should not be treated as motivational obstacles.

Do not turn a failed repetition into an unplanned series of forced repetitions or increasingly improvised movements.

Bottom line

Hard sets can be effective without reaching failure every time. Failure may still have a place, particularly when used selectively, but it adds fatigue and changes the safety demands of an exercise.

Choose the endpoint to serve your program, technique and recovery rather than following an absolute rule.

Sources

1. 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;42(1):85–101. https://pubmed.ncbi.nlm.nih.gov/38393985/ DOI: 10.1080/02640414.2024.2321021. ↩

2. 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;57(9):2021–2031. https://pubmed.ncbi.nlm.nih.gov/40249908/ DOI: 10.1249/MSS.0000000000003728. ↩

3. 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;9:10. https://pubmed.ncbi.nlm.nih.gov/36752989/ DOI: 10.1186/s40798-023-00554-y. ↩