Our recent meta-analysis (PMID: 39205815) suggests that inter-set rest intervals of approximately 90–120 seconds are needed to optimize muscle hypertrophy during intense resistance training. But this raises an important question: Are longer rest intervals inherently more conducive to muscle growth, or is their apparent advantage simply due to allowing a greater volume load to be performed? A study by Longo et al. (PMID: 35622106), in which I was a coauthor, sought to answer this question. We randomized 28 young, previously untrained participants perform resistance training twice weekly for 10 weeks, comparing 1-minute versus 3-minute rest intervals, with and without equating volume load (sets × reps × load). Results showed that when volume load differed between conditions, 3-min rest intervals produced ~13% growth in quadriceps muscle size, compared to ~7% with 1-min rest intervals. However, when volume load was equated, the advantage of longer rest disappeared, with both conditions producing similar gains. Collectively, the findings suggest that the hypertrophy advantage of longer rest intervals may be largely attributable to their ability to facilitate greater training volume, rather than the rest duration itself. Shorter rest periods can produce comparable muscle growth, but you may need to perform additional sets to compensate for the reduction in reps. The takeaway: Rest intervals are a tool, not a magic number. Longer rest periods can be a more efficient way to maintain training performance and accumulate volume, while shorter rests can also be effective when sufficient volume is achieved. A caveat: These findings were obtained in previously untrained individuals performing high-load leg presses. We can't necessarily generalize them to trained lifters or all exercises. ovid.com/jnls/nsca-jscr/full…