Reference : Exogenous glucose oxidation during exercise in relation to the power output.
Scientific journals : Article
Human health sciences : Cardiovascular & respiratory systems
Human health sciences : Endocrinology, metabolism & nutrition
Exogenous glucose oxidation during exercise in relation to the power output.
Pirnay, Freddy mailto [Centre Hospitalier Universitaire de Liège - CHU > > Pneumologie-Allergologie >]
Scheen, André mailto [Université de Liège - ULg > Département des sciences cliniques > Diabétologie, nutrition et maladie métaboliques - Médecine interne générale >]
Gautier, J. F. [> > > >]
Lacroix, M. [> > > >]
Mosora, F. [> > > >]
Lefebvre, Pierre [Centre Hospitalier Universitaire de Liège - CHU > > Diabétologie,nutrition, maladies métaboliques >]
International Journal of Sports Medicine
Thieme Medical Publishing Inc.
Yes (verified by ORBi)
[en] Adult ; Exercise Test ; Glucose/pharmacokinetics ; Humans ; Male ; Oxidation-Reduction ; Oxygen Consumption ; Physical Exertion/physiology ; Respiratory Mechanics
[en] In order to study the influence of the power output on the oxidation rate of exogenous glucose and on the contribution of the various substrates to the energy demand, we combined the use of artificially enriched 13C-glucose with classical indirect calorimetry during uphill treadmill exercise. Six young male healthy subjects underwent three exercise bouts, in a randomized order and at least two weeks apart, at a low (45% VO2max, 1822 +/- 194 ml O2/min for 4 hours), moderate (60% VO2max, 2582 +/- 226 ml O2/min for 3 hours), and high intensity (75% VO2max, 3036 +/- 287 ml O2/min for 2 hours). After 10 min of exercise, each subject ingested 100 g of artificially 13C-labelled glucose dissolved in 400 ml of water. Over the four hours of the exercise at 45% VO2max, the amount of exogenous glucose oxidized was 89.5 +/- 5.9 g from the 100 g ingested. In all exercise bouts, the oxidation of exogenous glucose already began during the first 30 min after ingestion and peaked at 120 min. The maximum oxidation rates averaged 0.64 +/- 0.07, 0.75 +/- 0.04, and 0.63 +/- 0.08 g/min, and the mean amounts of exogenous glucose oxidized over the first two hours averaged 51.7 +/- 8.0, 61.5 +/- 6.6 and 50.9 +/- 8.45 g, at 45, 60 and 75% VO2max respectively. The contribution of the oxidation of exogenous glucose to the total energy supply progressively decreased when the power output increased, from 19.6 to 12.2%. In the meantime, the contribution of total carbohydrates (exogenous+endogenous) progressively increased from 55.1 to 77.8% while the contribution of lipids decreased from 35.5 to 16.6%. In conclusion, exogenous glucose ingested during exercise is largely oxidized and strongly contributes to the energy supply. The oxidation rate first increases with the power output, but levels off or even decreases at high intensity exercise.

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