Bcaa’s consist of 3 essential amino acids leucine, isoleucine, and valine. Unlike other aminos, muscles can use BCAAs directly for fuel while your training. In addition BCAAs are used to repair muscle which means more muscle size. Because Bcaa’s are readily used by the muscles for fuel the longer and more intense you train the more Bcaa’ss will be drawn from the muscles. To counteract this, take Bcaa’s right before you train.