As a runner getting ready for a marathon, I've been reading up on certain vitamins/supplements. I've read that L-Carnitine helps to increase energy and improves resistance to muscle fatigue. It also helps build muscle and is used to treat some forms of cardiovascular disease. The other vitamin is Co ENzyme Q10 which is also critical for production of energy and stimulates the body's metabolism. I've been taking both of these vitamins for about 3 weeks but it's a little too soon to say they are the result of a new-found energy. I just wondered if anyone else has additional information or would recommend them.