Give it a rest: a systematic review with Bayesian meta-analysis on the effect of inter-set rest interval duration on muscle hypertrophy.
Level 1 - systematic review of randomized trials
Systematic review with Bayesian meta-analysis of randomized trials
PubMed 39205815 · doi:10.3389/fspor.2024.1429789
What was done
Authors conducted a systematic review and Bayesian hierarchical meta-analysis of randomized trials comparing different inter-set rest interval durations on pre- to post-study changes in lean/muscle mass in healthy adults while controlling other training variables. The meta-analysis included 19 measurements (thigh: 10, arm: 6, whole body: 3) from 9 studies.
What was found
Non-controlled standardized mean differences overlapped across rest durations: short was 0.48 (95% CrI: 0.19 to 0.81) versus longer at 0.56 (95% CrI: 0.24 to 0.86); across four categories, estimates were 0.47 (short), 0.65 (intermediate), 0.55 (long), and 0.50 (very long). Controlled binary pairwise meta-analyses favored longer rest for arm (0.13, 95% CrI: -0.27 to 0.51) and thigh (0.17, 95% CrI: -0.13 to 0.43), whereas whole body favored shorter rest (-0.08, 95% CrI: -0.45 to 0.29). Subanalysis showed set end-point (failure vs non-failure) did not meaningfully alter rest interval effects. Authors concluded a small benefit exists for rest >60 s, with no detected differences beyond 90 s.
Why it matters
Resting longer than 60 seconds between sets provides a modest advantage for muscle hypertrophy, but extending rest periods beyond 90 seconds does not appear to provide additional gains.
Limits
The analysis is based on only 9 studies, and total subject count is not reported in the abstract. Controlled pairwise credible intervals for all anatomical sites crossed zero, indicating substantial statistical uncertainty and heterogeneity.