The branched-chain amino acids (BCAAs) are leucine, isoleucine, and valine. BCAAs are considered essential amino acids because human beings cannot survive unless these amino acids are present in the diet.
BCAAs are needed for the maintenance of muscle tissue and appear to preserve muscle stores of glycogen (a storage form of carbohydrate that can be converted into energy). BCAAs also help prevent muscle protein breakdown during exercise.
Most diets provide an adequate amount of BCAA which is about 25–65 mg per 2.2 pounds of body weight. However, athletes involved in intense training often take 5 grams of leucine, 4 grams of valine, and 2 grams of isoleucine per day to prevent muscle loss and to increase muscle gain.
Dr Family Fitness 