The evolution of rest time in resistance training has transitioned from longer durations (2-5 minutes) influenced by powerlifting research, to shorter intervals (60 seconds) based on hormonal response studies, and now to a personalized approach considering training volume and individual preference. Present guidelines suggest resting around 2 minutes to sustain load and repetitions, or opting for shorter rests with extra sets to match volume load.
As resistance training was originally used as a sport itself (weightlifting and powerlifting), the amount of rest used between sets has always been long, typically between 2 to 5 minutes. There was very clear research from the former Soviet Union (who studied this kind of stuff with incredible passion) that longer rest between sets allowed greater loads to be lifted and better maintained power/bar velocity across the sets.
Resistance training was also used as a modality to improve speed and power sports, and these activities also employed long rest periods between sets. A lot of the tradition and ways of doing things in strength training for sport was adopted by bodybuilders, when that became a popular endeavor. In fact, many of the early bodybuilders were also powerlifters, weightlifters, and strongmen, as these sporting activities went hand-in-hand for those who lived and breathed iron in the gym. As such, many of the early bodybuilders also used several minutes rest between sets. And this became the established norm.
Then in the 1990s, new investigative techniques allowed sports scientists to look at the anabolic hormonal response to resistance training, and this quickly became a burgeoning area of research.
Scientists at the forefront of this field identified that the training protocols used for weightlifting and powerlifting - that is, heavy loads and long recovery periods – surprisingly, did not result in any appreciable change to the hormone levels in response to training. Rather, in a series of studies, the researchers found that short rest periods - around 60 seconds - with multiple sets and large muscle group exercises, had the greatest impact on the anabolic hormonal response to exercise. Because of these findings, 60-seconds became the new standard for rest periods between sets in resistance training sessions.
Then about 15 years ago, a group of researchers in Canada were able to contribute more to our understanding of muscle growth and rest between sets. They were able to skillfully show that, although particular training protocols most certainly increased the hormonal response to exercise (and other protocols did not), this transient bump up in hormones actually had no effect on the growth of muscle mass. A number of research groups have confirmed that the hormones are not nearly as important as what was once originally thought, but rather taking sets close to failure, which researchers use the term mechanical tension, and the number of sets and exercises you use for each muscle, known as training volume - where identified as being the two most important variables for muscle growth.
It is now considered that both effort and volume are, in fact, the primary variables to positively change muscle mass. As the rest intervals between sets increase, one can obviously lift more load. You will notice this if you perform 5 sets of squats and work close to your maximum for 10 reps. You’ll lift more weight if you rest 2 minutes between sets rather than 60 seconds. Additionally, several studies found that short rest between sets had the potential to blunt muscle protein synthesis, but the mechanisms behind this phenomenon are only speculative for now.
Along the lines of effort, researchers looked at the effect of a concept called volume load, and this is where you identify the maximum amount of weight that you lift across the sets you perform for an exercise, and for every exercise performed in that training session.
As the maximum load that one can lift is a very strong indicator that the highest amount of mechanical tension has been placed upon the muscle, this concept becomes very important for muscle mass. We essentially have two ways that we can generate high tension and volume in a training session: The first is that we can perform a given number of sets and reps for the chosen exercises – working in close proximity to failure - resting the recommended period of time, which is typically around 2 minutes, according to the most recent position stands on muscle growth. If we note the amount of weight that we lift across every set for every exercise, then we obtain the volume load for each muscle group.
However, for those individuals who do not like resting such a long period between sets and would prefer to rest a minute or even less, then there will be a trade off with how much load that will be lifted. But research has shown that if you perform an additional set(s) for each exercise, the volume load equates to performing fewer sets at a higher load. And for muscle, as far as our current understanding goes, does not seem to mind.
This leaves us with two options for rest between sets.
Option 1 for strength and muscle mass, the recommended rest between sets is around 2 minutes. The most important consideration is to ensure that you rest a sufficient amount of time so that there is not a reduction in load or repetitions across the number of sets your performing for each exercise. This is typically between 90 seconds and up to 3 minutes, depending on whether the exercise has been taken to failure, the number of joints, and the amount of muscle mass used in the exercise. In other words, you might rest 90 seconds for an isolated, single-joint movement, but you might rest up to 3 minutes after complex exercises, such as deadlifts and squats. With the most important consideration is that there is no drop off in load or repetition number across the sets.
Option 2 is for those individuals who do not enjoy resting between sets. Firstly, be aware that there will be a drop off in load or repetitions between sets if you are performing exercises in close proximity to failure. However, you can feel confident that if you add another set or two per exercise, then volume load will be equated, compared to performing heavier loads with longer rest and there will be no penalty to muscle mass. This seems to be the more important variable, at least for muscle mass, this has not been studied where strength and power is the primary outcome. But most lines of evidence would suggest that you can't increase volume load with more sets and hope to increase strength and power, as these rely on different neuromuscular mechanisms.
So, there are two different rest options to match your personality, and both will give you the same outcomes for healthy muscle as we age. We no longer choose our rest period based on the hormonal response to exercise but rather, we choose based on the duration allowing us to lift the most weight possible or for the time crunched, we reduce the rest and do more sets. A few roads to Rome in this case.
References:
Longo AR, Silva-Batista C, Pedroso K, de Salles Painelli V, Lasevicius T, Schoenfeld BJ, Aihara AY, de Almeida Peres B, Tricoli V, Teixeira EL. Volume Load Rather Than Resting Interval Influences Muscle Hypertrophy During High-Intensity Resistance Training. J Strength Cond Res. 2022 Jun 1;36(6):1554-1559. doi: 10.1519/JSC.0000000000003668. Epub 2020 Jun 5. PMID: 35622106.
Roberts MD, McCarthy JJ, Hornberger TA, Phillips SM, Mackey AL, Nader GA, Boppart MD, Kavazis AN, Reidy PT, Ogasawara R, Libardi CA, Ugrinowitsch C, Booth FW, Esser KA. Mechanisms of mechanical overload-induced skeletal muscle hypertrophy: current understanding and future directions. Physiol Rev. 2023 Oct 1;103(4):2679-2757. doi: 10.1152/physrev.00039.2022. Epub 2023 Jun 29. PMID: 37382939; PMCID: PMC10625844.
Schoenfeld, B. J., Fisher, J. P., Grgic, J., Haun, C,T., Helms, E T., Phillips, S, M., Steele, J., Vigotsky, A, D. (2021).Resistance Training Recommendations to Maximize Muscle Hypertrophy in an Athletic Population: Position Stand for the IUSCA. International Journal of Strength and Conditioning https://doi.org/10.47206/ijsc.v1i1.81
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