Research indicates that short inter-set rest intervals (≤60 seconds) can compromise muscle hypertrophy, while resting longer than ~90–120 seconds does not seem to further enhance muscle growth. In practice, however, most people regulate their rest intervals subjectively instead of timing them. How does this affect muscle development? Interestingly, no previous study investigated the topic. Until now...
Led by my doctoral student
@ae.mohan, we randomized resistance-trained men and women to an 8-week lower-body resistance training program using either a fixed 2–3-minute inter-set rest interval or a self-selected rest condition in which participants initiated each subsequent set when they felt ready (just preprinted on SportRxiv:
sportrxiv.org/index.php/serv…). To ensure that self-selected rest intervals reflected perceived recovery rather than external distractions, participants were not permitted to use mobile devices or converse with others during training sessions.
After 8-weeks, both groups achieved similar gains in muscle hypertrophy, strength, and local muscular endurance. However, the fixed-rest group completed their workouts in 29% less time than the self-selected group (average rest intervals: 2.4 vs. 3.7 minutes, respectively). That’s particularly striking because we didn’t allow participants to talk or use their phones. In a real-world gym environment, those distractions would almost certainly make self-selected rest periods even longer.
Couple of takeaways. First, these findings reinforce the idea that resting longer than about 2 minutes between sets doesn’t appear to provide any additional muscle-building benefit. Second, for those who are short on time, actively timing rest intervals seems to be a practical strategy. Given that lack of time is consistently cited as the leading barrier to exercise participation, simply setting a timer between sets may help improve workout efficiency—and ultimately, adherence to resistance training.
As always, a huge shout-out to my graduate students for bringing this research to fruition. Their dedication and hard work are the driving force behind our productivity 💪