ABSTRACT
β-hydroxy-β-methylbutyrate (HMB) is a metabolite of leucine, a branched chained amino acid which functions as an effective stimulator of muscle protein synthesis. This chapter explores the proposed mechanisms of action for HMB raging from its effect on intramuscular signalling to its immunomodulatory properties. It aims to compare common formulations of the compound along with effective dosing strategies. The chapter discusses the effects of acute supplementation with HMB and its influence on markers of muscle damage, immune cells, physical function and recovery from strenuous muscular exertion. While HMB has gained popularity primarily in the athletic realm, it reviews its efficacy in relation the clinical populations such as those with sarcopenia, cachexia and other chronic conditions. In addition to an ability to enhance myofibrillar protein synthesis rates, HMB appears to exert its most prominent effects by reducing catabolism from muscle protein breakdown. The chapter concludes with a discussion of the safety and legality of HMB for various populations and application in sport.
