Metabolic Responses When Different Forms of Carbohydrate Energy Are Consumed during Cycling

Abstract

This study examined the effects of consuming the same amount of carbohydrate in solid form, liquid form, or both on metabolic responses during 2 hrs of cycling at 70% peak VO2 and on cycling time-trial performance. Subjects consumed 0.4 g carbohydrate/kg body mass before and every 30 min during exercise. The liquid was a 7% carbohydrate-electrolyte beverage and the solid was a sports bar (1171 kJ) in which 76%, 18%, and 6% of total energy was derived from carbohydrate, fat, and protein, respectively. Blood obtained at baseline, before exercise, and every 30 min was analyzed for glucose, insulin, lactate, hemoglobin, hematocrit, and plasma volume. There were no differences among the treatments for the blood parameters. Total carbohydrate oxidation and time-trial performance were also similar among treatments. Under thermoneutral conditions with equal liquid ingestion, the metabolic and performance responses are similar when consuming carbohydrate as a liquid, solid, or in combination during prolonged, moderate intensity cycling.