The mammalian target of rapamycin, more commonly known as mTOR, plays an important role in regulating cell growth and protein synthesis. mTOR Complex 1 (mTORC1) is the part of this function responsible for integrating nutrient, growth factor and energy input. The BCAA leucine has a reputation for stimulating protein synthesis, and it's a key modulator of mTORC1. A recent study published in the journal Amino Acids suggests that glutamine can activate mTORC1 independent of leucine.
As the most abundant amino acid in muscle, many strength athletes supplement with glutamine to aid the recovery process. It's a conditionally essential amino acid, so when levels are depleted through intense physical effort your body may not be able to completely replace these aminos quickly enough. If you're elevating the intensity of your workout for a bulking phase or competition preparation, adding 5 grams of L-glutamine to your post-workout shake might help take your recovery to the next level.