8. Creatine
Runners who are also meat eaters can benefit from creatine since it is a byproduct of protein metabolism in the body. Like L-carnitine, it is made available to all areas of the body so it can provide energy for cells and enhance the performance of muscles. Creatine supplements are available which will be beneficial for runners who do not eat meat, and for those who simply wish to increase their levels of this organic acid.