L-Leucine is an essential Amino acid, specifically classified as a "branched-chain amino acid" (BCAA). BCAA's, especially Leucine, stimulate muscle protein synthesis and may be the major fuel involved in anabolic reactions. This makes them especially important for body builders and other arthletes in sports that demand explosive strength. Leucine, isoleucine, and valine are the three branched-chain amino acids (BCAAs) that are highly effective for stimulating skeletal muscle protein synthesis. Interestingly, leucine has much greater power on stimulating protein synthesis compared to any other amino acid.