Developer's DescriptionBy SerincBranched-Chain Amino Acid (BCAA) Another category of muscle-building supplements that lifters and bodybuilders use to improve their results are...Branched-Chain Amino Acid (BCAA) Another category of muscle-building supplements that lifters and bodybuilders use to improve their results are branched-chained amino acids (BCAAs), or BCAAs. Of the 20 amino acids that make up protein, just three are referred to as BCAAs: leucine, isoleucine, and valine