We’ve all had those moments watching a client struggle through their final reps, their face contorted in determination, sweat dripping, and just as they’re about to give up, we shout, “One more rep!” and they somehow dig deep and push through. It’s the classic training scenario, but is it always the best approach? We encourage them to dig deep, to squeeze out those last few reps and to embrace the burn because, after all, isn’t that what builds muscle? The idea that progress comes from pushing to the point of failure is ingrained in the fitness industry, and let’s be honest, it feels good to see a client collapse on the mat after a tough session, knowing they gave everything they had.
But is training to failure really the best approach? While it certainly has its place, new research suggests that stopping just short of failure, leaving a rep or two in the tank, may be just as effective for building muscle and strength while being easier on the body and mind. In fact, constantly training to failure might be doing more harm than good, particularly when it comes to long-term motivation and adherence.
What the Research Says
A recent study, published in the European Journal of Sport Science, took a closer look at how training to failure affects the way people perceive their workouts. Conducted by Refalo et al. (2025), the study compared training to momentary muscular failure (FAIL) with stopping one or two repetitions before failure (RIR, or Repetitions In Reserve) over an eight-week resistance training program.
Rather than using a simple comparison of different groups, the researchers designed an interesting within-subject study. Each participant trained one leg to failure and the other with 1-2 RIR, allowing the researchers to make direct comparisons within the same individual. This eliminated differences in genetics, pain tolerance, and training history as confounding factors, making the results more reliable.
The study recruited experienced lifters, men and women who had been training consistently for an average of 7.6 years, with many of them having competed in bodybuilding or powerlifting. This is an important distinction because much of the existing research on training failure is conducted on beginners, whose responses may differ from those of trained individuals.
The researchers also took an innovative Bayesian statistical approach to analyse the data. Unlike traditional statistics, which rely on p-values and binary conclusions, Bayesian analysis provides probability estimates, meaning it calculates the likelihood of a result being true rather than just determining if it is statistically significant. This approach helps provide a more intuitive and flexible interpretation of data, offering a more nuanced understanding of how likely certain results are to be true. This approach allows for a much clearer interpretation of the findings.
The study also controlled for menstrual cycle phase in female participants. Rather than scheduling training around specific phases, the researchers allowed women to participate regardless of cycle stage. This decision was based on growing evidence that menstrual cycle fluctuations have minimal impact on resistance training outcomes, at least at the group level.
Finally, the researchers measured how well participants could estimate their repetitions in reserve. Many trainers worry that if clients don’t train to failure, they won’t push themselves hard enough. However, the study found that participants were quite accurate in judging how many reps they had left in the tank. On average, they were within one rep of their target. This suggests that experienced trainees can effectively regulate their effort even when they don’t push to absolute failure.
What Happens When You Stop Just Short of Failure?
The study found clear differences in how participants felt during and after training to failure compared to stopping with a couple of reps left.
First, perceived discomfort (RPD) was higher in the failure condition. This isn’t surprising; pushing a muscle to absolute exhaustion is, by nature, uncomfortable. But what was interesting is that discomfort ratings didn’t improve over time. Even after eight weeks, training to failure still felt just as unpleasant as it did in week one. In contrast, those training with 1-2 RIR found their discomfort levels slightly decreased over time.
Perceived exertion (RPE) also remained consistently higher in the failure condition. Again, this makes sense. Pushing to failure requires more effort. But what’s important to note is that this increased effort didn’t translate to better results in muscle growth or strength. Previous research, including a study by Refalo et al. (2024), has already shown that stopping with a couple of reps in reserve leads to similar hypertrophy and strength gains as training to failure, but with less fatigue.
Perhaps the most striking finding was that general feelings about the workout (FS) were significantly worse in the failure group. While some participants tolerated failure-based training well, others reported increasingly negative feelings over time. By week eight, the gap in enjoyment between the two protocols had grown even larger. This suggests that repeatedly pushing to failure might have a negative effect on long-term training adherence, making people less likely to stick with their program.
Applying This to Personal Training
So, should we stop pushing our clients to failure? Not necessarily, it depends on the individual and their goals.
For clients training for muscle hypertrophy or general strength, stopping with 1-2 RIR appears to be just as effective as failure, while reducing discomfort and making workouts feel more enjoyable. This means they may be more likely to stick with their program long-term, which is ultimately what matters most.
For athletes focused on maximal strength, such as powerlifters, occasional training to failure may be beneficial, particularly for testing limits or during specific peaking phases. However, for most of their training, staying just shy of failure is likely the better approach, allowing for more training volume without excessive fatigue.
The client’s personality and motivation also matter. Some people thrive on pushing to their limits, finding a deep sense of satisfaction in grinding out that last rep. Others may find it discouraging, exhausting, or even off-putting. Understanding what motivates each client is key.
Training commitment is another factor. A highly motivated client training 4-5 times a week might be better served by avoiding failure most of the time to keep fatigue in check. A casual gym-goer training twice a week might be fine pushing to failure more often, since their overall volume is lower.
The Takeaway
The idea that training to failure is necessary for progress is largely a myth. While some research suggests that training to failure can maximize muscle fibre recruitment, other studies indicate that similar hypertrophy and strength gains can be achieved with submaximal effort. Additionally, training to failure may lead to excessive fatigue, which could impact recovery and long-term adherence. While it can be useful in certain situations, consistently stopping just short of failure, leaving 1-2 reps in reserve, can provide the same muscle and strength gains while making workouts more enjoyable, less exhausting, and possibly more sustainable over the long run.
As personal trainers, our job isn’t just to push our clients hard, it’s to keep them training consistently and enjoying the process. For instance, imagine working with two different clients: one who thrives on pushing to failure and another who feels discouraged when every session leaves them completely drained. By adjusting the training intensity based on their preferences, we can keep both clients motivated and committed to long-term progress. If pushing to failure every session makes them dread their workouts, they’re far more likely to quit. Instead, focusing on effective, sustainable training strategies is the best way to help them reach their goals while actually looking forward to their next session.
Reference:
Refalo, M. C., Helms, E. R., Hamilton, D. L., & Fyfe, J. J. (2025). The effect of proximity-to-failure on perceptual responses to resistance training. European Journal of Sport Science, 25(e12266). Click here to read the full research article.
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