I bought this to test glutamine out. I did not notice any real effects, but I am not a heavy body-builder, more of a runner. What I did notice is that I recovered much better after a very long run (7+ miles). Sometimes after a run of this length I would "crash" and feel like I had to sleep or just very low energy, a bad mental state. Eating correctly before/after also will help but I found these capsules to noticeably decrease this problem.