Skeletal muscle is the most abundant tissue in the human body, so the fact it serves as the primary amino acid pool supplying the body with proteins in times of need is no surprise, especially when your bodily systems are under conditions of stress, including dieting, heavy training and injury. Scientists have been very interested in the pathways that mediate muscle wastage in such conditions. Recent research indicates hyperexpression of myostatin is a key player in this response. In the most basic sense, myostatin in the body acts as the brakes for muscle growth.
Glutamine, the most abundant amino acid in skeletal muscle, is depleted during and after heavy stress. Years of research has demonstrated supplementing with glutamine before and after your training sessions leads to greater protein synthesis and decreased catabolism.
Evidence indicates the muscle-sparing and anabolic effects of glutamine supplementation are a direct outcome of its ability to inhibit myostatin, essentially taking the “brakes” off muscle growth. In a study publishes in Amino Acids, researchers showed that when muscle cells were exposed to TNFα (to induce catabolism) and supplemented with glutamine, the process completely reversed the hyperactivity of myostatin and therefore halted catabolism.
Since its genetic discovery in 1997 supplement research and development teams have been on a dedicated search to fine safe and effective compounds that inhibit myostatin. Remarkably they have discovered a well-known amino acid can effectively reverse the negative impact of myostatin hyperactivity. Although this study was completed in vitro (in a controlled environment such as a test tube or Petri dish, not in a living organism), it provides a powerful mechanism for the muscle-sparing effect of glutamine, therefore reinforcing the importance of pre and post-workout glutamine supplementation.