Effects of HMB on Endurance Performance in a Healthy Population: A Systematic Review and Meta-Analysis.

Fernández-Landa, J, Todorovic, N, Santibañez-Gutierrez, A, Ostojic, SM, Calleja-González, J, Sekulic, D, and Mielgo-Ayuso, J. Effects of HMB on endurance performance in a healthy population: a systematic review and meta-analysis. J Strength Cond Res XX(X): 000-000, 2023-β-hydroxy-β-methylbutyrate (HMB) has been used extensively as a dietary supplement for athletes and physically active people. However, the ergogenic effect of HMB supplementation on endurance performance is still unclear. Therefore, this systematic review and meta-analysis (SRMA) aimed to assess HMB supplementation on endurance performance and V̇O2 max. This SRMA followed PRISMA guidelines. Three electronic databases were searched (PubMed/Medline, Web of Science [WOS], and Scopus) from inception until April 3, 2023. In this SRMA, human experimental trials, controlled with a placebo group, assessing the effect of HMB supplementation on endurance performance in a healthy population were included. The quality of the studies was assessed by the Physiotherapy Evidence Database (PEDro) scale. The study protocol was registered in the Prospective Register of Systematic Review (PROSPERO): CRD42022341790. Eleven studies involving 279 participants met the inclusion criteria. The results displayed a significant improvement on endurance performance (pooled standardized mean difference [SMD] = 0.58 [0.28-0.87]) and V̇O2 max (pooled SMD = 0.58 [0.21-0.95]) after HMB ingestion. Moreover, after the exclusion of the studies not evenly distributed around the base of the funnel plot, the results continued to be significantly positive in endurance performance (pooled SMD = 0.38 [0.22-0.53]) and V̇O2 max (pooled SMD = 0.25 [0.09-0.42]). In conclusion, HMB (3 g·d-1) ingestion during 2-12 weeks significantly improves endurance performance and V̇O2 max.