Sports
Glutamine

L-glutamine is the most abundant amino acid in our body, and perhaps the most critical supplement for athletes. Glutamine is one of the structural units of RNA and DNA and, as such, a key component of proteins and nucleotides. It is estimated that 60% of the body's glutamine resides in the muscles and, in effect, becomes the body's reserve supply. When glutamine plasma levels become low, glutamine is released from the muscles to satisfy the need for synthesizing proteins and nucleotides. Although glutamine is considered a non-essential amino acid, one that can be "manufactured" by the body, some people believe it is "conditionally" essential, especially during and after intense exercise.

During periods of intense exercise, glutamine plasma levels may decrease 32-50%. As muscles donate glutamine to the body, they become "flat," they break down, have less strength, and create a poor environment for muscle growth (which is a major reason overtraining is not recommended). Furthermore, lowered glutamine levels weaken the immune system. In a double-blind study reported in the European Journal of Applied Physiology, researchers gave athletes 5 grams of glutamine after high intensity workouts. Only 19% of the group reported colds or similar infections over the next seven days as opposed to 51% of the placebo group.

When glutamine levels are high, protein is synthesized in the body and muscles are "volumized" (a process where water molecules are pulled into the muscle cell, making them look fuller.) In addition, increasing glutamine levels increases human growth hormone levels, which add to muscle size. In a study published in the American Journal of Clinical Nutrition, researchers reported that two grams of glutamine taken after a light breakfast increased human growth hormone 432%. And according to Dr. Ronald Katz, MD, president of the Academy of Anti-Aging Medicine in Chicago, "Glutamine binds to the hydrogen ions in the lactic acid and neutralizes them. This allows your body to generate higher levels of force production before muscle failure. You can also resume exercise sooner than otherwise would be possible."

In a nutshell, glutamine:

increases protein synthesis
decreases muscle breakdown
increases muscle workload before failure
shortens recovery time
elevates growth hormone
protects the immune system
and volumizes muscles.

Athletes should take between 8 and 20 grams per day, spread out in 2-4 gram doses. Protein supplements typically provide 2 grams of glutamine. Effective times to take glutamine are: first thing in the morning, before exercise, after a workout, and just before going to bed. Like creatine, glutamine should be loaded–heavy doses taken over several days–to start a regimen.