Training to failure: benefits and risks

'The last repetition is the most important' is a popular phrase in the gym. But do muscles really grow better when every set ends in complete failure? The editorial team analyzed meta-analyses on proximity to failure, hypertrophy, strength and recovery and explains when failure is appropriate and when it only adds fatigue and risks.

What failure is and what kinds there are

Muscular failure is the moment in a set when the athlete cannot perform one more repetition through the full range of motion with correct technique, despite maximal effort. This is the most common definition in scientific work, although in practice the line between 'technical' failure (when technique begins to break down) and 'absolute' failure (when the bar does not move at all) can be blurred.

Training to failure means programs in which some or all working sets are taken to this state. The alternative is stopping with a certain repetition reserve, for example 1-3 repetitions short of failure. In studies this reserve is often estimated by the RIR scale (repetitions in reserve) or by loss of movement speed.

There are also 'beyond failure' techniques: forced repetitions with a partner's help, drop sets with reduced weight, partial repetitions, rest-pause. They prolong the set and increase fatigue but do not necessarily enhance adaptation.

Why is this question important? Failure is the simplest way to guarantee that a set was hard enough. At the same time it sharply increases fatigue, and therefore affects the rest of the workout and recovery. So the question is not whether failure 'works' but when its benefits outweigh the cost.

Failure and hypertrophy: research data

The meta-analysis by Grgic et al. (2022) compared training to failure and without it. The authors found no significant difference in the gain in muscle mass between the groups when volume was comparable. That is, stopping a few repetitions short of failure produced similar muscle growth.

Refalo et al. (2023) analyzed proximity to failure in more detail. Their meta-analysis showed that hypertrophy increases when sets are performed closer to failure, but the difference between failure and stopping 1-2 repetitions short is small. In contrast, sets with a large reserve (for example, 5 or more repetitions) produced noticeably less growth.

So for hypertrophy it is important to train 'close' to failure but not necessarily to reach it. This especially applies to light weights: in a set of 20-30 repetitions the first repetitions give little stimulus, and only approaching failure makes the set effective.

The practical conclusion: stopping 0-2 repetitions short of failure in most sets provides almost all of the hypertrophy potential while reducing fatigue.

Failure and strength

For developing maximal strength the data are even clearer. The meta-analysis by Davies et al. (2016) found no advantage of training to failure compared with training without it in terms of strength gains. Strength largely depends on neural adaptation and the quality of movement with heavy weights, and failure worsens technique and increases fatigue.

The study by Pareja-Blanco et al. (2017), with control of movement speed, showed that the group that stopped a set after a 20% loss of speed had a similar or better gain in strength and jump performance than the group with a 40% loss of speed (closer to failure), although the latter had somewhat greater hypertrophy. In addition, in the group with greater fatigue, undesirable changes in muscle fiber type were observed.

For strength athletes, failure in the basic exercises has another cost: the risk of injury. A drop in technique in the squat or deadlift on the last repetition is a situation best avoided, especially without a spotter.

That is why in strength programs failure is usually reserved for accessory exercises or individual test sets, while the main work is done with a reserve of 1-3 repetitions.

Fatigue, recovery and risks

The main drawback of training to failure is disproportionately high fatigue. Morán-Navarro et al. (2017) showed that after training to failure the recovery of mechanical performance and hormonal markers took significantly longer than after training with the same volume but without failure. Fatigue could persist for 24-48 hours.

This has direct practical consequences: if the first set is performed to failure, the following ones will have to be done with less weight or fewer repetitions. As a result, the total volume of quality work in the workout may decrease.

There are also medical risks. Maximal efforts with straining sharply increase blood pressure, which is undesirable for people with hypertension or cardiovascular diseases. For people after injuries and surgeries, training to failure without a doctor's approval is not recommended.

Finally, constant work to failure is psychologically exhausting. Many athletes notice a decrease in motivation if every workout turns into a struggle with maximal efforts.

How to use failure wisely

To summarize, the editorial team proposes the following practical principles for athletes seeking hypertrophy and strength without unnecessary risks.

• perform the main volume with 1-3 repetitions in reserve;
• take to failure mainly the last set in isolation or machine exercises;
• avoid failure in heavy basic exercises without a spotter;
• periodically test failure to calibrate your RIR estimation;
• reduce the number of sets to failure during periods of stress and poor sleep.

A useful practice for beginners is to occasionally take safe exercises to failure to understand where it really is. Many people underestimate their reserve and stop 4-6 repetitions short of failure, believing they are working 'to the limit.'

For experienced athletes, failure can be a tool of intensification in certain phases of the training cycle, for example at the end of a mesocycle before a deload.

For more detail on load planning, read our articles on progressive overload, on the number of sets per muscle group and on training periodization.

Editorial conclusions

Training to failure does not provide a significant advantage for hypertrophy or strength compared with working close to failure at equal volume. The main thing is that the sets be hard enough, that is, end 0-3 repetitions short of failure.

The cost of failure is disproportionately great fatigue, longer recovery, a higher risk of technical errors and injuries.

The sensible decision is to use failure selectively: in isolation exercises, in the final sets and for calibrating the sense of effort.

References

1. 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 Med. 2023;53(3):649–665.
2. 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. J Sport Health Sci. 2022;11(2):202–211.
3. Davies T, Orr R, Halaki M, Hackett D. Effect of training leading to repetition failure on muscular strength: a systematic review and meta-analysis. Sports Med. 2016;46(4):487–502.
4. Pareja-Blanco F, Rodríguez-Rosell D, Sánchez-Medina L, et al. Effects of velocity loss during resistance training on athletic performance, strength gains and muscle adaptations. Scand J Med Sci Sports. 2017;27(7):724–735.
5. Morán-Navarro R, Pérez CE, Mora-Rodríguez R, et al. Time course of recovery following resistance training leading or not to failure. Eur J Appl Physiol. 2017;117(12):2387–2399.
6. Helms ER, Cronin J, Storey A, Zourdos MC. Application of the repetitions in reserve-based rating of perceived exertion scale for resistance training. Strength Cond J. 2016;38(4):42–49.