Leucine and Strength

Leucine regulates muscle protein synthesis through the mammalian target rapamycin (mTOR), which influences cell growth. Also, evidence points to increases in collagen synthesis by supplementing leucine. The improvement in muscle protein synthesis and collagen synthesis suggest faster recovery rates from high intensity training. The ability to recover faster may allow the person to train more frequently.

There is a metabolite of leucine called Beta-Hydroxy-Beta-methylbutyrate (HMB) that has shown to increase muscle mass. Yet, there is other research displaying negligible benefits in trained subjects using HMB in respect to strength. On one hand, Portal et al found increases in muscle mass, muscle strength and anaerobic properties in national level volleyball ball players after supplementing with 3 g/day of HMB. On the other hand, an article from The Journal of Strength and Conditioning Research reported no effect on muscular power strength and endurance. However, experimental research that treated rats with HMB demonstrated an increase in extensor digitorum muscle and an increase in mTOR expression, but induced a significant rise in fasting insulin. Here is study investigating long term usage of HMB in rat models that eventually lead to insulin resistance and hyperinsulinemia. It appears that HMB may not provide much of an advantage toward improving athletic performance or increases in strength in highly conditioned athletes even when combined with creatine, according to the research here, here and here.