Use of endogenous carbohydrate and fat as fuels during exercise

Abstract

Carbohydrate and fat are the major fuels used by working muscles during exercise. The use of these substrates requires the mobilization of endogenous reserves present in adipose tissue, liver, and skeletal muscle and delivery to muscle mitochondria for oxidation. The integration of these processes is complex and is affected by many factors. In the present article we will review the effect of exercise duration, exercise intensity, and aerobic fitness on carbo-hydrate and lipid metabolism during endurance exercise in human subjects.