As a performance coach, one of the first things we’re taught when it comes to resistance training are the general guidelines for developing strength, power and hypertrophy. For example, to develop maximal strength, trainee’s should train with greater than 85% of their 1RM for multiple sets of 5 or less reps and rest between 3-5 minutes between sets. For hypertrophy, we’re taught that we should train with between 55-84% for multiple sets of 8-12 reps with 60 – 90 seconds rest between sets. The shorter rest period is supposed to facilitate greater metabolite accumulation, greater cellular swelling and possibly increased growth hormone concentrations. Recently, researchers are challenging these guidelines to determine if these are the most effective methods for improving the desired outcome (e.g., strength or hypertrophy).
A new study published ahead of print in the Journal of Strength and Conditioning Research put rest periods head to head in an experiment. Twenty-one resistance trained males were randomly split into a group that utilized short rest periods (i.e., 1 minute) and a group that used long rest periods (i.e., 3 minutes) between sets. The training intervention lasted for 8 weeks and had the subjects perform 3 full-body workouts per week. The subjects performed 3 sets of 8-12RM with 7 different exercises during each training session. The programs for both groups were the same apart from the rest periods. Before and after the training period, 1RM bench press and squat, muscular endurance (reps to failure with 50% of 1RM bench press) and muscle thickness were evaluated.
The results showed that 1RM strength improved significantly more in the group using longer rest intervals than the group using short rest intervals. Muscle thickness also improved significantly more for the group using longer rest periods. Improvements in muscular endurance were not significantly different among the two groups. The researchers concluded that longer rest periods are more effective for inducing greater gains in muscular strength and hypertrophy than shorter rest periods. This may be due to longer rest periods enabling individuals to use greater loads during their sets which creates more mechanical tension and potentially greater muscle damage. Both of which are potent stimulators of skeletal muscle adaptations.
Schoenfeld, BJ. et al. Longer inter-set rest periods enhance muscle strength and hypertrophy in resistance-trained men. Journal of Strength and Conditioning Research, Ahead of print.