The BCAA’s, L-Leucine, L-Isoleucine, and L-Valine, are probably the most essential amino acids for athletes in training. They account for 33% of muscle protein. Some experts believe that even moderate exercise can increase your body’s need for Leucine by up to 240%. By taking Reflex Nutrition BCAA’s before and after exercise you can increase nitrogen retention, boost protein synthesis, and protect your muscles from the stress and trauma of heavy exercise.