D-ribose is a sugar naturally present in the body that is used for medicinal purposes. It seems that the intake of ribose can prevent muscle fatigue associated with some genetic diseases that prevent the body from producing sufficient energy. It is also credited with the ability to supply additional energy to the heart during physical activity practiced by patients with heart disease. The use of this sugar is proposed both to improve athletic performance and increase the energy available to the muscles, and to reduce the symptoms of problems such as chronic fatigue syndrome, fibromyalgia, coronary heart disease, AMPD deficiency and McArdle’s disease (or myophosphorylase deficiency).