L-Glutamine is the most abundant amino acid in muscle tissue, but can become depleted during intense exercise - which decreases strength and lengthens recovery.
Glutamine also plays an important role in protein synthesis (the creation of muscle tissue) and for best results needs to be in a positive balance.
On top of that, Glutamine is the major component in the immune factor Glutathione, a deficiency of which often leaves hard-training athletes vulnerable to colds or infections.
Athletes and bodybuilders most often take supplemental L-Glutamine before, during, and after training to improve endurance, reduce muscle breakdown, and accelerate recovery.
L-Glutamine can also be taken with meals, to replace muscle Glutamine stores, and rebuild Glutathione levels. Dosages range from 5 grams up to 20 grams per day for the serious user (or burns victim).