I know that Dr Lam's office prescribes it for adrenal fatigue sufferers before & after exercise. I think the idea is that the amino acids help replenish the body.
I didn't feel an actual difference when taking it, though, and am not sure about the accuracy of the science behind it..
A large flaw with the hypothesis is again that collagen only contains a few of the many amino acids utilized by the body. Although it is a good source of glycine, which is great for tissue repair.