BCAA's include leucine, isoleucine and valine. They are needed for the maintenance of muscle during physical stress and exercise. Research shows that supplementation with branched-chain amino acids can prevent central fatigue by tightly regulating the influx of tryptophan to the brain. Supplementation before and during exercise has been proven to enhance performance. BCAAs function as anabolic agents and induce sparing, which allows the body to burn fat and not muscle. 100 percent crystalline BCAA 12,000 powder is designed to increase endurance, lengthen the time to fatigue and improve performance. Ultimate Nutrition used only the finest USP quality amino acids for this formula.