Effect of repetition duration during resistance training on muscle hypertrophy: a systematic review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of experimental trials
PubMed 25601394 · doi:10.1007/s40279-015-0304-0
What was done
Systematic review and meta-analysis evaluating the effect of repetition duration during resistance training on muscle hypertrophy. Eligible studies were experimental trials in healthy humans lasting at least 6 weeks that directly compared dynamic exercise tempos (concentric and eccentric actions) performed to muscle failure, with muscle growth measured by biopsy, imaging, or densitometry. Eight studies met inclusion criteria.
What was found
The abstract provides no numerical effect estimates or confidence intervals. It reports that hypertrophic outcomes were similar across repetition durations ranging from 0.5 to 8 seconds per repetition. Super-slow training (>10 seconds per repetition) appeared inferior for hypertrophy, though controlled comparative data were limited.
Why it matters
Athletes and lifters have flexibility in selecting repetition tempo across a broad range (0.5 to 8 s) without compromising hypertrophic gains, provided sets are taken to failure.
Limits
The abstract reports only 8 included studies and does not provide sample sizes, participant demographics, training status, or quantitative effect sizes. Very few controlled studies investigated repetitions exceeding 10 seconds, precluding definitive conclusions on super-slow training.