Muscular exercise, lactic acid, and the supply and utilisation of oxygen. Part IX. —Muscular activity and carbohydrate metabolism in the normal individual

Abstract
It has long been discussed what substance is primarily responsible for the provision of energy in muscular contraction. The protein hypothesis of Liebig was abandoned in his later years. It was found that the greater excretion of uric acid, or the appearance of creatinin after severe exercise, was merely due to the splitting of the components of muscular tissue,i. e., protein is not used for the provision of energy. Chauveau (1) assumed the conversion of fat into carbohydrate and a 30 percent, loss of energy in this conversion. Chauveau’s conclusion was discussed by Zuntz (2). He put forward the assumption that the muscles, whether resting or active, utilise fat and carbohydrate in the proportion in which these are presented to them.