Rest times are often one of those programming variables that are easy to overlook. If you are anything like me you have fallen into a routine at the gym, and just train with little thought about the amount of time of your workout or between exercises. One of the primary reasons for working out is to either increase size, strength or both. The internet is rich with articles about how many reps, sets, exercises, or even what tempos you should train at too achieve these goals. In my experience little attention is payed to the amount of rest time needed to maximize size and strength gains.
If you are serious about your goals however you may want to pay closer attention to the amount of time you are taking between your exercises thanks to some exciting new research. General guidelines have been in place for trainees who want to gain strength, size, or power. For instance strength gain is typically thought to happen at >85% of 1RM for multiple sets of 3-5 reps with approximately 3-5 minutes rest between them. Similarly for size gains we are typically taught to utilize lower percentage of 1RM, 55 – 85% for multiple sets of 8-12 repetitions on 60-90 seconds rest. The reasoning is that shorter rest periods are supposed to create greater muscle damage, metabolite accumulation, cellular swelling (THE PUMP), and even increased growth hormone concentrations. Well new research has come out that challenges these classic prescriptions for size and strength with the hopes of determining what is most effective.
A recently published study in the Journal of Strength and Conditioning Research looked at different rest periods compared to each other in order to determine how effective each was in promoting size, strength, and endurance adaptations. To test this the researchers looked at 21 resistance trained males split into either a group that utilized shorter rest periods (1 minute) or longer rest periods (3 minutes). For 8 weeks the 2 groups performed 3 full-body workouts a week. The training sessions included 3 sets of 8-12RM with 7 exercises. The only difference between both groups was the amount of time that they rested between sets. At the conclusion of the training program muscular strength was assessed through 1RM bench press and squat testing. Muscular endurance and muscular size were also tested utilizing reps to failure at 50% 1RM bench press, and ultrasound imaging respectively.
The study concluded that athletes who were performing the longer rest periods improved significantly in the 1RM tests when compared to the shorter rest group. What’s more surprising is that muscle size also improved more substantially in the group that utilized longer rest periods. Finally muscular endurance improvements were not meaningfully different between groups.
These results led the authors to conclude that longer rest periods may be better for achieving greater muscular size and strength gains. The suggested reasons for this were that longer rest periods allowed athletes to utilize higher weights which would increase the overall load lifted per workout. With increased load the authors speculated that subjects would have sustained increased muscle damage, and mechanical tension both of which are shown to be drivers in 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.