Synergistic Effect of Increased Total Protein Intake and Strength Training on Muscle Strength: A Dose-Response Meta-analysis of Randomized Controlled Trials.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 36057893 · doi:10.1186/s40798-022-00508-w
What was done
Systematic review and dose-response meta-analysis of randomized controlled trials identified from PubMed and Ichushi-Web through March 2022. The study evaluated the dose-response relationship between total protein intake and muscle strength gains, analyzing groups with and without concurrent resistance training using random-effects and spline models.
What was found
Across 82 included articles (69 used for spline models): - Muscle strength gain was significantly augmented by protein intake only with concurrent resistance training (MD 2.01%, 95% CI 1.09 to 2.93). - Protein intake without resistance training showed no significant effect on muscle strength (MD 0.13%, 95% CI -1.53 to 1.79). - With resistance training, muscle strength showed a dose-dependent increase of 0.72% (95% CI 0.40 to 1.04%) per 0.1 g/kg body weight/day increase in total protein intake up to 1.5 g/kg body weight/day, with no further gains observed above this threshold.
Why it matters
It demonstrates that protein supplementation does not improve muscle strength without resistance training and identifies a clear plateau for strength gains at 1.5 g/kg body weight/day.
Limits
The abstract does not report total participant counts, participant demographics (e.g., age, sex, training status), intervention durations, or potential differences by protein source and quality.
Cited by
- supports During resistance training, the majority of strength and muscle-building benefits from protein are achieved at 1.2 g/kg, with minimal additional benefits gained between 1.2 and 1.6 g/kg.