Effects of Creatine Supplementation and Resistance Training on Muscle Strength Gains in Adults <50 Years of Age: A Systematic Review and Meta-Analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of controlled trials
PubMed 39519498 · doi:10.3390/nu16213665
What was done
A systematic review and meta-analysis of four databases (MEDLINE, Scopus, Embase, SPORTDiscus) through May 22, 2024, evaluated the effects of creatine supplementation combined with resistance training on muscle strength in adults under 50 years of age. The analysis included 23 studies comprising 509 total participants: 20 studies in males (447 participants), 2 in females (40 participants), and 1 in mixed sexes (13 males, 9 females). Subgroup analyses evaluated participant sex, creatine dosage, training duration, and other confounding variables.
What was found
Compared with placebo, creatine supplementation combined with resistance training significantly increased upper-body strength (weighted mean difference [WMD] = 4.43 kg, p < 0.001) and lower-body strength (WMD = 11.35 kg, p < 0.001). In sex-stratified analysis, males achieved significant increases in both upper- and lower-body strength, whereas females showed no statistically significant gains, with a trend toward greater upper-body strength gains in males compared to females (p = 0.067, Q = 3.366). A trend also favored greater lower-body strength gains from high-dose compared with lower-dose creatine (p = 0.068, Q = 3.341). No other analyzed variables modified the effect.
Why it matters
This review quantifies the expected strength gains from creatine supplementation combined with resistance training in adults under 50, while highlighting a significant disparity in evidence and response between males and females.
Limits
The evidence base is heavily skewed toward male participants (460 males vs. 49 females across 23 studies), which severely underpowers conclusions regarding female efficacy. Specific definitions of high versus low dose, training programs, dietary controls, and safety outcomes were not detailed in the abstract.