Combined effects of strength training, whey protein, and HMB on sarcopenia in older people

Background: Although previous studies have reported the benefits of combining physical activity with supplementation on body composition and physical performance in older people with sarcopenia, previous meta-analysis often included heterogeneous interventions, combining multiple types of supplements. Therefore, this systematic review and meta-analysis aimed to analyze the available body of published peer-reviewed randomized controlled trials (RCTs) studies on the effects of strength training (ST) combined with supplementation (S) (ST + S) using whey protein (WP) and beta-hidroxi-beta-metilbutirato (HMB) on body composition, physical performance, and biomarkers in older people with sarcopenia. Methods: Using 6 databases PubMed, Medline, Cumulative Index to Nursing and Allied Health Literature Complete, Scopus, Cochrane Library, and Web of Science a thorough literature search was carried out to March 2025. The Grading of Recommendations Assessment, Development, and Evaluation, Tool for the assEssment of Study qualiTy and reporting in EXercise, Rob 2, and Preferred Reporting Items for Systematic reviews and Meta-Analyses tools were used to evaluate the methodological quality and certainty of evidence. Hedge g effect sizes were computed. Potential sources of heterogeneity, such as subgroup analyses (type of supplements or training vs supplementation), were chosen using a fixed- or random-effects model. The protocol (code CRD42025643858) was registered in International Prospective Register of Systematic Reviews. Results: Of 2322 records, 7 RCTs with 472 participants were included. These 7 studies showed a high methodological quality ≥10 points in Tool for the assEssment of Study qualiTy and reporting in EXercise. Four overall meta-analysis showed significant increases ( P < .05) in fat-free mass (effect sizes [ES] = 0.39), maximal isometric handgrip strength (MIHS, ES = 1.38), chair stand test (ES = 0.33), and 6-minute walk test (ES = 0.33). In the subgroup meta-analysis, the ST + S subgroup showed a significant increase ( P < .01) in MIHS compared to supplementation alone. Similarly, WP combined with ST was associated with a significant improvement in MIHS (ES = 0.49), whereas no significant improvement was observed with HMB combined with ST. In contrast, in fat mass and knee extension strength, no significant differences were reported between ST + S and ST or S. Conclusion: ST combined with WP or HMB supplementation may contribute to improvements in fat-free mass and selected physical performance outcomes in older people with sarcopenia. However, the limited number of RCTs, relatively small sample sizes, moderate-to-high risk of bias, and inconsistent subgroup findings indicate that the current evidence should be interpreted cautiously and considered promising rather than definitive.