I've known many athletes who supplement with the amino acid glutamine in an effort to enhance performance. I am generally against supplementing with high doses of specific amino acids since nature does not provide them that way. Glutamine poses an additional problem of possibly elevating glutamate levels in the brain. Normally glutamate levels are very carefully monitored in the brain--just the right amount is a good thing, but excess can actually excite cells to death (this is what MSG and aspartame do--the G in MSG is for glutamate). Anyway, I found a study titled "The effects of high-dose glutamine ingestion on weightlifting performance." The results were this: "These data indicate that the short-term ingestion of glutamine does not enhance weightlifting performance in resistance-trained men." In summary, there is possible risk with no apparent benefit to glutamine supplementation. Read the study.