L-Isoleucine is one of the essential amino acids that cannot be made by the body and is commonly used for athletic performance as it may support endurance and assist in the repair and rebuilding of muscle.

L-Isoleucine, like Valine and L-Leucine is a Branch Chain Amino Acid (BCAA), and they may assist providing fuel to muscle cells, sparing other amino acids from being burned up. Like the other BCAAs, Isoleucine supports the synthesis of protein in the muscle cell, allowing repair and growth. It is common to find some range of BCAAs in some protein powders, or as a BCAA supplement.