Riddell, M. C., Heigenhauser, G. J., & Bar-Or, O. (1999). Glucose intake spares endogenous carbohydrate and contributes to the energy demand of exercise in boys. Medicine and Science in Sports and Exercise, 31(5), Supplement abstract 879.

"The influence of glucose ingestion on fuel utilization during prolonged exercise in children and adolescents is currently unknown. " (p. S194) Healthy boys aged 12-16 years, exercised for two hours at 60% VO2max on a cycle ergometer while ingesting either water of Gatorade.

Compared with water intake, the carbohydrate solution intake lowered endogenous glucose utilization (-16%) and increased plasma insulin (226%) and whole blood glucose (37%). The extra carbohydrate in Gatorade contributed to approximately 25% of the total energy demand of exercise.

Implication. Endogenous glucose is spared if carbohydrate drinks are ingested during prolonged exercise in adolescent males.

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