Carbohydrate and lipid oxidation during exercise

Abstract

In this paper, evidence is put forward to suggest that sheep are well adapted to maintain a supply of carbohydrate for contracting muscle when compared to other mammals such as the human athlete. This is achieved by a remarkable ability to maintain or even elevate glucose concentration in the blood through 'feed forward' control of glucose metabolism. Glycogen, whether hepatic or muscle, is also readily utilized at work rates above the anaerobic threshold. The ability to replace glycogen is substantial in sheep which are adapted to exercise and in type IIA muscle is not greatly lower than in non-ruminant animals. Aspects of long chain fatty acid (NEFA) metabolism are also discussed. An interesting finding in sheep is the partial oxidation of NEFA to acetate during sustained exercise at above the anaerobic threshold. This represents a mechanism to increase the power of fat oxidation and deserves attention in other species.