HAMMER WHEY is the standard for promoting rapid recovery. For rebuilding of lean muscle tissue and optimal immune system functioning between workouts and races, whey protein has no peer. It is the most bioavailable form of protein and has the highest percentage of essential amino acids, the protein building blocks that your body does not manufacture and must be obtained from dietary sources. Moreover, 25% of the essential amino acid component comes from the three most important amino acids for muscle tissue repair, the branched-chain amino acids (BCAAs) leucine, isoleucine, and valine.