Muscle-building is the result of greater muscle protein synthesis than muscle breakdown. Generally speaking, exercise "wakes" up proteins to get to work and amino acids, or protein assistants, flow through the blood stream to repair damaged, worn out muscle tissue. As a result, extra protein gathers in the weakened areas to create a larger muscle for next time.
Leucine is an essential amino acid, meaning one that is not synthesized naturally in the body. Found in soy protein, egg whites, brown rice, nuts and supplements, leucine helps prevent the breakdown, or degradation, of muscle protein during exercise by promoting muscle growth. Studies have found leucine to be 10 times more anabolic (muscle-building) than any other amino acid. In fact, one 2008 experiment published in the “Journal of Physiology” found that a diet high in leucine inhibited the loss of muscle in aged rats. Similar research at the Washington University School of Medicine using the elderly concluded the same results for humans.
Whey is the by-product of cheese, a liquid mixture of lactose (milk sugar), water and other nutrients. When dried, it can be added to different foods for flavor or removed of fat and non-protein substances to be made into a supplement known as whey protein.
Whey protein is one of the most used muscle-building supplements. Unlike leucine which depends on other amino acids to be synthesized, whey protein is complete with all amino acids readily available. It can also be metabolized directly into muscle tissue and help fight against certain illnesses. The Whey Protein Institute states that by elevating levels of glutathione (the body’s strongest antioxidant), whey protein heightens the immune system and reduces a woman’s risk of breast cancer.
Leucine Vs. Whey Protein
Whey protein already contains a number of leucine amino acids within its chemical configuration. For this reason, taking leucine alone will not provide any greater benefit than taking whey protein alone. Furthermore, leucine, because it is not a complete protein, relies on valine, isoleucine and other amino acids to function. Whey protein, on the other hand, does not. Yet because it is a byproduct of dairy, whey may cause stomach discomfort if overtaken by someone who is lactose intolerant.
Advantages of Combining the Two
In the “Journal of Strength and Conditioning Research,” scientists found that adding leucine to whey protein drinks improved muscular strength and lean muscle mass greater than whey protein alone. Apparently, the addition of leucine spikes insulin levels five times higher resulting in more energy and assumedly longer, more intense workouts. Also, leucine aids in producing more amino acids in the blood stream, easing the ability of the muscle to grow larger.