The effect of protein timing on muscle strength and hypertrophy: a meta-analysis.
Level 1 - systematic review of randomized trials
Meta-analysis and meta-regression of randomized controlled trials
PubMed 24299050 · doi:10.1186/1550-2783-10-53
What was done
The authors conducted a multi-level meta-regression of randomized controlled trials evaluating the effects of consuming protein in and around exercise sessions (protein timing) on muscle strength and hypertrophy. The strength analysis evaluated 20 studies comprising 478 subjects across 41 treatment or control groups (96 effect sizes). The hypertrophy analysis evaluated 23 studies comprising 525 subjects across 47 treatment or control groups (132 effect sizes). Both simple pooled analyses and full meta-regression models controlling for covariates were evaluated.
What was found
In simple pooled analysis without covariate adjustment, protein timing had a small to moderate effect on muscle hypertrophy and no significant effect on muscle strength. In the full meta-regression model controlling for all covariates, no significant differences remained between treatment and control groups for either strength or hypertrophy. Total daily protein intake emerged as the strongest predictor of effect size magnitude for hypertrophy. The abstract reports no numerical effect sizes, confidence intervals, or exact p-values.
Why it matters
This study refutes the belief that peri-workout protein timing is critical for muscular adaptations. It indicates that meeting adequate total daily protein intake alongside resistance training is the primary dietary driver of muscle growth.
Limits
The abstract reports no numerical effect sizes, variances, or p-values. Participant demographics (e.g., trained vs. untrained, age, sex), study durations, and specific protein sources or doses are not reported in the abstract.
Cited by
- supports Consuming dietary protein within 30 minutes versus 3 hours after a resistance training session does not alter the extent of muscle adaptation.