title: Respective oxidation of exogenous glucose and fructose given in the same drink during exercise.
abstract: We computed the respective amounts of exogenous glucose (G) and fructose (F), which are oxidized during exercise when ingested simultaneously, with the use of 13C labeling. Six subjects exercised for 2 h at 60.7 +/- 2.9% of maximal O2 uptake on a cycle ergometer while ingesting 50 or 100 g of G or F or a mixture of 50 g each of G and F in 500 ml of water. The amount of exogenous G oxidized increased from 37.8 +/- 2.2 to 58.3 +/- 8.1 g when the total amount ingested increased from 50 to 100 g. The amount of F oxidized was significantly lower (32.2 +/- 1.2 and 45.8 +/- 2.6 g for the 50 and 100 g ingested, respectively). When 50 g each of G and F were simultaneously ingested in the same drink, the amounts oxidized (39.5 +/- 4.8 and 34.1 +/- 1.5 g, respectively) were similar to those observed when 50 g of G or F were ingested separately. The cumulative amount of exogenous hexoses oxidized (73.6 +/- 6.6 g) was 21% larger than when 100 g of G were ingested. This finding could be due to the fact that the routes for absorption and metabolism of exogenous G and F are at least partly different, resulting in less competition for oxidation when a mixture of these two hexoses is ingested than when an isocaloric amount of G is ingested. From a practical point of view, these data may provide experimental support for using mixtures of carbohydrates in the energy supplements for endurance athletes.
authors.affiliation: Département d'Education Physique, Université de Montréal, Quebec, Canada.
authors.forename: E
authors.initials: E
authors.lastname: Adopo
authors.forename: F
authors.initials: F
authors.lastname: Péronnet
authors.forename: D
authors.initials: D
authors.lastname: Massicotte
authors.forename: G R
authors.initials: GR
authors.lastname: Brisson
authors.forename: C
authors.initials: C
authors.lastname: Hillaire-Marcel
mesh_terms: D000284:Administration, Oral; D000328:Adult; D002245:Carbon Dioxide / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005223:Fats / Q000493:pharmacokinetics; D005632:Fructose / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005947:Glucose / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology
chemical_list: D005223:Fats; D002245:Carbon Dioxide; D005632:Fructose; D005947:Glucose