You have time for a shorter workout, and the first exercise is nearly finished. The last rep slows down. Another one might go up; after that, you are less sure. Setting the weight down can feel like leaving the job unfinished, especially when this is the only working set you planned for that exercise.
A trial in experienced lifters offers a different perspective: one set per exercise produced strength gains even when people stopped with an estimated two repetitions left. Reaching failure was optional; meaningful effort was still part of the workout.
Table of contents
A small routine, with an important comparison
The study published in 2025 followed 42 young, resistance-trained adults for eight weeks. Both groups performed one set of each of nine exercises, twice weekly. One group took every set to muscular failure, the point where another full repetition was not possible. The other stopped when they believed two more reps were possible.
Strength improvements were similar between groups. Some measurements of muscle growth tended to favor failure, although the differences were generally modest. That distinction matters: building strength and increasing muscle size are related goals, but they are not identical outcomes.
The comparison was between stopping points, not single-set and three-set programs. An eight-week trial in trained young adults cannot establish the best routine for beginners or elite lifters.
What leaving two reps actually means
Imagine you finish your eighth curl and believe you could complete two more with the same technique. That is the idea behind repetitions in reserve, often shortened to RIR. If you could comfortably do another eight, that is a different level of effort.
The estimate concerns what your muscles could still do, rather than the number printed on your workout plan. A target of 10 reps does not automatically tell you whether the tenth rep was challenging.
Broader guidance is consistent with leaving some capacity unused: the American College of Sports Medicine’s 2026 update says training to momentary failure does not consistently determine results for the average healthy adult. It emphasizes regular, effortful training that fits the person’s goals.
That leaves room for a hard set to end while you still control the weight. It does not make an easy set equivalent to a demanding one.
Keep the whole workout in the picture
One set per exercise still means doing several exercises. Dropping the words “per exercise” from the headline changes the routine considerably.
For general health, the CDC recommends muscle-strengthening activity at least two days a week, covering the major muscle groups. Its guidance starts with at least one set and notes that two or three can provide additional benefits.
If you are deciding what to do with a limited gym visit, distinguish a manageable amount of challenging work from a token effort. Choose the exercises you can execute well, and be honest about how much you have left when each set ends.
The decision to add sets is separate from taking every set to failure. You can revisit your training volume as your goals change without making failure the test of whether today’s workout counted.