Leucine and HMB

SUMMARY: Leucine is a branched chain amino acid (BCAAs). BCAAs (leu, isoleucine and tryptophan) can be taken as a supplement to enhance muscle recovery after a hard workout. A 5 g dose is taken by athletes after a hard workout to repair muscles. But taking a 5 g dose activates the mTOR pathway. Activating the mTOR pathway may decrease lifespan, because Inhibition of mTOR is known to extend lifespan in experimental animals. So there is reason both for and against taking leucine or BCAA supplements.

Leucine has recently been shown to prevent sarcopenia in the elderly.

Reasons to take leucine supplements Reasons to avoid leucine

HMB is a metabolic by-product of the essential branched-chain amino acid (BCAA), leucine, which has key roles in protein metabolism. In humans undergoing resistance training, HMB supplementation increased lean mass gains from 50 to 200%, with similar percentage increases in strength when compared with unsupplemented subjects [ref]. The effects of HMB on muscle size and function seems to result from a diminution of exercise-related muscle damage and muscle protein breakdown.
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