Strength training combined with whey protein may improve muscle mass and grip strength in older adults
A systematic review of 7 randomized controlled trials involving 472 older adults with sarcopenia examined whether combining strength training with whey protein or HMB (a metabolite that may support muscle) improved muscle composition and physical function. Strength training plus whey protein showed meaningful gains in handgrip strength and fat-free mass, but results were inconsistent across studies and effect sizes were modest to moderate.
Sarcopenia—age-related muscle loss—is linked to falls, disability, and reduced quality of life in older people. Researchers systematically reviewed 7 high-quality randomized controlled trials (total 472 participants) to test whether pairing strength training with whey protein supplementation or HMB could improve outcomes beyond either intervention alone.
Across all studies combined, the combination approach was associated with increases in fat-free mass (effect size 0.39), maximal isometric handgrip strength (effect size 1.38), chair stand test performance (effect size 0.33), and 6-minute walk distance (effect size 0.33)—all statistically significant. When researchers separated studies by supplement type, whey protein combined with strength training showed a meaningful effect on handgrip strength (effect size 0.49), whereas HMB combined with strength training did not. However, the authors identified critical limitations: only 7 RCTs met inclusion criteria, sample sizes were small, several studies had moderate-to-high risk of bias, and subgroup findings were inconsistent. Fat mass and knee extension strength showed no significant differences between the combined approach and strength training or supplementation alone. The authors conclude the current evidence should be viewed as promising rather than definitive.
The handgrip strength effect size of 1.38 is notably larger than the effect on fat-free mass (0.39) or walking distance (0.33), suggesting the combination may have a preferential effect on upper-body strength. Whey protein showed clearer benefits than HMB when paired with training, hinting that the leucine-rich amino acid profile of whey may be the active ingredient. Interestingly, supplementation without structured strength training did not produce similar gains—training itself appears essential. The meta-analysis authors note that heterogeneity across studies was significant for some outcomes, meaning intervention duration (ranging across studies), protein dose, training frequency, and participant baseline characteristics all likely influenced results. The modest effect sizes and limited sample sizes mean individual responses could vary substantially. Publication bias cannot be ruled out, as studies showing null results are less likely to be published.
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