A group of amino acids (leucine, isoleucine, valine) metabolized by muscle tissue rather than the liver.
Branched-chain amino acids are those amino acids with a branch in their hydrocarbon side-chain. These amino acids include leucine, isoleucine, and valine. BCAA are often described separately from other amino acids not only because of their similarities in structure, but also their similarities in function. In particular, unlike other amino acids, BCAA (especially leucine) can be oxidized to some extent for energy in non-hepatic tissues, such as the muscle, which is one reason that BCAA have received much attention as potential ergogenic aids.
Amino acids that have side chains with a branch (a carbon atom bound to more than two other carbon atoms), such as leucine, isoleucine, or valine.