Building muscle is a complex process and is often a balance between anabolism, the buildup of protein, and catabolism, the breakdown or loss of tissue. For the strength athlete, the key to getting stronger is to promote anabolism and simultaneously prevent catabolism. Because your body's protein balance is in a constant state of flux, taking in additional protein is one way to help the body build more muscle mass and strength.
Researchers at Temple University in Philadelphia, PA, reported in the journal Nutrition that certain combinations of amino acids may prevent the breakdown of muscle tissue. Researchers T. P. Stein and colleagues administered either three nonessential amino acids (glycine, serine and alanine) or three branched-chain aminos (leucine, isoleucine and valine) to 19 healthy subjects ages 22-37 during six days of restricted bed rest. When they measured urinary excretion of nitrogen and 3-methylhistidine (a biochemical gauge of muscle breakdown), nitrogen retention was greater for the BCAA group.
This study reinforces the idea for adding BCAA to your supplemental strategy to maintain muscle tissue especially after an injury or surgery, or when you're sick and forced to take a layoff from training.