Prolonged or intense exercise places a great demand on energy sources in the body to supply ATP and can result in a mismatch between ATP supply and demand. Post-exercise increases in ammonia are indicative of a mismatch between ATP supply and demand. A recent study showed that supplementation with carnitine
(2 g/day) for 2 weeks reduced the ammonia response to exercise (90 min of cycling). Exactly how carnitine reduced ammonia was not addressed but it could relate to more efficient fat burning during exercise because carnitine is critical in this process.
Stuart DL, Galloway DR. Effects of 2 weeks supplementation with L-carnitine L-tartrate on plasma ammonia response to exercise. Federation of American Societies for Experimental Biology, Washington D.C., April, 2004. Abstract #502.5.