Klean Endurance contains pure D-Ribose, a safe and clinically researched ingredient that supports the natural way our bodies produce adenosine triphosphate (ATP), the energy currency of the cell. Our bodies must have an adequate supply of d-ribose to form major cellular constituents such as our genetic material (DNA and RNA), numerous cofactors, certain vitamins, and, importantly, adenosine triphosphate (ATP). D-Ribose accentuates the body’s natural process of energy synthesis. It helps to reduce the loss of energy during stress and accelerates energy and tissue recovery. Through this action, D-Ribose helps muscles regenerate lost energy and potentially minimizes any physiological consequences of this energy depletion situation. Energy depletion contributes to a variety of consequences that may negatively impact muscle performance or how we feel after exercise. The loss of energy in muscles directly contributes to the common symptoms of stiffness, soreness, weakness, and pain due to exercise. Protein synthesis, of vital importance to athletes, can also be affected. The effect of D-Ribose administration on exercise performance has been examined. In a four-week study involving recreational body builders, ribose was given to determine its effect on body composition and exercise performance. While there was no difference in pre/post exercise body composition between the ribose and placebo groups, the ribose group showed significantly greater gains in both muscle strength and endurance. D-Ribose administration has also been shown to increase exercise tolerance and performance with decreased muscle stiffness, pain, and fatigue.