Volume Load Rather Than Resting Interval Influences Muscle Hypertrophy During High-Intensity Resistance Training.
Level 2 - randomized trial
Within-subject randomized controlled trial comparing unilateral limb training protocols
PubMed 35622106 · doi:10.1519/JSC.0000000000003668
What was done
Twenty-eight subjects participated in a 10-week resistance training study (twice weekly) performing unilateral knee extensions at 80% of 1RM. Legs were allocated to one of four protocols: 3-minute long rest intervals (LI), 1-minute short rest intervals (SI), short rest with volume load matched to LI (VLI-SI), or long rest with volume load matched to SI (VSI-LI). Pre- and post-training 1-repetition maximum (1RM) and quadriceps cross-sectional area (QCSA) were evaluated.
What was found
All protocols produced significant increases in 1RM post-training (p < 0.0001) with no significant differences among protocols: LI increased 27.6% (ES = 0.90), VLI-SI increased 31.1% (ES = 1.00), SI increased 26.5% (ES = 1.11), and VSI-LI increased 31.2% (ES = 1.28). QCSA increased significantly across all protocols (p < 0.0001). However, absolute increases in QCSA were significantly greater (p < 0.05) in higher volume-load conditions (LI: 13.1%, ES = 0.66; VLI-SI: 12.9%, ES = 0.63) than in lower volume-load conditions (SI: 6.8%, ES = 0.38; VSI-LI: 6.6%, ES = 0.37).
Why it matters
This study demonstrates that the hypertrophic advantage often attributed to longer interset rest intervals is primarily mediated by the greater volume load achieved rather than an independent resting effect.
Limits
The abstract does not specify participant sex or baseline training status. The investigation was limited to a single-joint exercise (knee extension) over 10 weeks, so findings may not directly generalize to multi-joint compound exercises or long-term training adaptations.