Leucine metabolite β-hydroxy-β-methyl butyrate (HMB) supplementation on muscle mass during resistance training in older subjects: meta-analysis

Abstract

Background: Aging, which is accompanied by loss of muscle mass, strength, and function, may contribute to the development of frailty and fractures in older people. Interventions such as β-hydroxy-β-methyl butyrate (HMB) treatment and resistance exercise training (RET) have been well established independently to attenuate muscle loss in previous researches. Nevertheless, no consensus exists on whether the combination of HMB intervention and RET could obtain an additional benefit to the older population. Our aim was to systematically quantify whether HMB supplementation combined with RET has a synergistic effect on improving muscle mass, strength, and function in older adults. Methods: A systematic search was performed using the electronic databases Medline, Embase, Cochrane Library, and Web of Science from inception of the study until Oct 30, 2021. The articles included were all randomized controlled trials and met the inclusion. A fixed or randomized (if data were heterogeneous) effects metaanalysis was performed using Stata. Results: A total of 256 articles were screened, with eight studies matching the eligibility criteria, which enrolled 333 subjects (≥ 65 years old). A meta-analysis was conducted, and the results showed no significant difference between the groups in lean mass, fat mass, or physical performance. In the subgroup analysis regarding the differences in muscle strength between appendicular muscles, HMB supplementation combined with RET contributed to significantly improving the muscle strength of the lower limbs (n = 6, SMD: 0.55, 95% confidence interval: 0.06 to 1.04). Conclusion: A combination of HMB supplementation and RET in older people has an additional benefit for muscle strength, especially in the lower limbs, instead of muscle function and physical performance. Further studies are needed to demonstrate the mechanism.