D-Ribose is a simple sugar used by all living cells and is essential for cellular metabolism as a major component of the genetic material, RNA and DNA. Ribose is also a structural component of ATP, the primary energy source for exercising muscle. However, during intense muscular activity, the total amount of available ATP becomes depleted. Ribose supplementation has been shown to support ATP regeneration following intense exercise; it may also help to support normal exercise tolerance. L-Carnitine is included because it facilitates the transfer of fatty acids into the mitochondria for cellular energy production. NOW&ampreg; Liquid Ribose Cellular Energy therefore contains two compounds that help to provide the fuel that working muscle needs for optimal performance.*