Effects of protein supplementation combined with resistance exercise on body composition and physical function in older adults: a systematic review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 28814401 · doi:10.3945/ajcn.116.143594
What was done
A systematic review and meta-analysis of online databases was conducted to identify randomized controlled trials evaluating the effects of protein supplementation combined with resistance exercise training versus resistance exercise alone in older adults. Evaluated outcomes included lean mass gain, leg strength gain, and physical mobility, with subgroup analyses based on mean body mass index (BMI greater than or equal to 30 versus less than 30 kg/m2).
What was found
Seventeen RCTs were included (overall participant mean age 73.4 ± 8.1 years; mean BMI 29.7 ± 5.5 kg/m2). Protein supplementation combined with resistance exercise yielded significantly greater lean mass gains (standardized mean difference [SMD]: 0.58; 95% CI: 0.32, 0.84) and leg strength gains (SMD: 0.69; 95% CI: 0.39, 0.98) compared to resistance training alone. In the subgroup with mean BMI ≥30, lean mass gains (SMD: 0.53; 95% CI: 0.19, 0.87) and leg strength gains (SMD: 0.88; 95% CI: 0.42, 1.34) remained significantly greater. The subgroup with BMI <30 also showed relevant gains, but specific numerical effect sizes were not provided in the abstract. Mobility outcomes were also omitted from the abstract results.
Why it matters
This review demonstrates that protein supplementation enhances muscle mass and strength adaptations from resistance exercise in older adults, confirming benefits in both obese and non-obese populations.
Limits
The total number of individual participants was not reported in the abstract. Numerical outcomes for physical mobility and the exact effect sizes for the BMI <30 subgroup were not stated in the abstract. Variations in protein source, dosage, intervention duration, and study quality across included RCTs were not detailed.
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