One of the biggest challenges that strength and conditioning coaches face is how to best manage the limited time that they are given with their athletes. Therefore, coaches need to get the most bang for their buck in terms of exercise selection and programming. One way to be more economical with training time is to determine the minimal amount of rest required between sets so that precious time is not wasted. Rest intervals are an often overlooked component of program design. According to what we learn in Exercise Physiology class, strength and power training generally require between 3-5 minutes of rest to restore ATP and allow the muscles to recover. For muscular endurance, 30 seconds is typically the prescribed rest interval.
Some new research published online ahead of print in the Journal of Sports Science and Medicine challenges the conventional rest interval durations that are so often prescribed. Martorelli et al. (2015) compared maximal power output, muscular activity and blood lactate concentrations following rest intervals that ranged between 1 and 3 minutes in twelve resistance trained men. After a familiarization and 1 rep max testing session, the subjects performed 3 squat workouts in a randomized order with 60% of their 1RM for 6 sets of 6 reps. The workouts were separated by between 3 and 7 days to control for fatigue and/or soreness.
The results showed that peak power differed between the rest intervals where 1 min rest saw a decrease of 5.6%, 2 min rest saw a 1.9% decrease and 3 min rest saw a 5.9% decrease. Average power showed a mean decrease of 10.5% for 1 min, 2.6% for 2 min, and 4.3% for 3 min after the 6 sets. Blood lactate levels were highest in the 1 min rest workout and lowest in the 3 min rest workout, though these differences were not significant. Muscle activity did not change significantly between rest interval groups.
These findings have important implications for rest interval prescription during moderate load power training. It appears that 2 minutes is the sweet spot for maintaining power output. However, 3 mins of rest was not much better than 1 min. Therefore, under strict time constraints, 1 min rest periods would likely be sufficient while 2 mins appear to be optimal. To put things in perspective, the authors note that 1 min rest intervals would enable one to complete the 6 sets of 6 reps in approximately 7 min, 12 minutes with 2 min rest intervals and 17 min with 3 min rest intervals. Prescribing 1-2 minutes of rest rather than 3-5 may allow for greater training density without significantly impacting power output.
André Martorelli, Martim Bottaro, Amilton Vieira, Valdinar Rocha-Júnior, Eduardo Cadore, Jonato Prestes, Dale Wagner, Saulo Martorelli, (2015) Neuromuscular and Blood Lactate Responses to Squat Power Training with Different Rest Intervals Between Sets. Journal of Sports Science and Medicine (14), 269 – 275.