HMB is also a metabolite of the BCAA leucine and both have been shown to stimulate protein synthesis through the mTOR pathway.
HMB stimulates protein synthesis in muscle by multiple mechanisms, including the mTOR/p70S6k pathway, which stimulates translation initiation of protein synthesis. (Many of these effects are shared with leucine; however, HMB is more potent than leucine in promoting strength gains).
HMB decreases protein breakdown at a molecular level caused by intense training. HMB results in decreasing the key regulating components of the ubiquitin-proteasome proteolytic pathway, which results in LESS muscle loss and damage.
Therefore, the increase in synthesis and decrease in breakdown result in greater gain of strength and faster recovery.