Longer Interset Rest Periods Enhance Muscle Strength and Hypertrophy in Resistance-Trained Men.
Level 2 - randomized trial
Individual randomized controlled trial.
PubMed 26605807 · doi:10.1519/JSC.0000000000001272
What was done
Twenty-one resistance-trained young men were randomized to an 8-week resistance training program comparing 1-minute interset rest intervals (SHORT) versus 3-minute rest intervals (LONG). All other resistance training variables were kept constant across 3 weekly full-body sessions (3 sets of 8–12 RM for 7 exercises). Pre- and post-study testing assessed 1RM squat and bench press, 50% 1RM bench press endurance to failure, and ultrasound muscle thickness of the elbow flexors, triceps brachii, and quadriceps femoris.
What was found
Maximal strength gains were significantly greater for LONG compared to SHORT for both 1RM squat and bench press. Muscle thickness increases were significantly greater in LONG for the anterior thigh, alongside a trend toward greater increases in the triceps brachii (p = 0.06). Both groups increased local upper-body muscle endurance without significant between-group differences. The abstract reported no exact numerical baseline or post-test values.
Why it matters
The findings challenge traditional bodybuilding recommendations that prescribe short rest intervals for hypertrophy, demonstrating that longer rest periods promote superior muscle size and strength adaptations in experienced lifters.
Limits
The sample size was very small (n = 21) and restricted entirely to young, resistance-trained men. The duration was limited to 8 weeks, and the abstract omits specific numerical effect sizes, percentages, or variance metrics.
Cited by
- supports Scientific evidence does not support the idea that taking shorter rest periods between sets enhances muscle growth.