Fructose May Help Maintain Liver Glycogen during Prolonged Endurance-type Exercise

Previously published research has shown that carbohydrate feeding during prolonged (>2 hour) moderate-to-high intensity, endurance-type exercise enhances endurance performance and capacity. The improvement in exercise performance has previously been attributed to high rates of carbohydrate oxidation which prevent hypoglycemia and may spare muscle glycogen. However, it is well known that glycogen stores in the liver are important for metabolic regulation and exercise tolerance. Glycogen is the body’s storage of energy that is readily available and is known to influence exercise performance.

A recent study tested the hypothesis that high rates of carbohydrate ingestion would spare liver glycogen during prolonged exercise, and that sucrose ingestion would better maintain liver glycogen relative to glucose ingestion. When athletes consumed sufficient carbohydrates, the reduction in glycogen was reduced. The researchers believe that the body’s ability to uptake and use mixtures of fructose and glucose is better than the ability to absorb and use a single simple sugar.