Carbohydrate Supplementation and Sex Differences in Fuel Selection during Exercise

• Autores: Jonathan H. Tremblay, Francois Peronnet, Denis Massicotte, Carole Lavoie
• Localización: Medicine & Science in Sports & exercise: Official Journal of the American College of Sports Medicine, ISSN 0195-9131, Vol. 42, Nº. 7, 2010, págs. 1314-1323
• Idioma: inglés
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• Resumen

  • Purpose: To compare the effects of a high-CHO diet (80% CHO) and glucose ingestion (2 g[middle dot]kg-1) during exercise (120 min, 57% V[spacing dot above]O2max) on fuel selection in women taking (W+OC) or not (W-OC) oral contraceptives and in men (six in each group).

    Methods: Substrate oxidation was measured using indirect respiratory calorimetry in combination with a tracer technique to compute the oxidation of exogenous (13C-glucose) and endogenous CHO.

    Results: In the control situation (mixed diet with water ingestion during exercise), the percent contribution to the energy yield (%En) of CHO oxidation was higher in men than in women (62 vs 53 %En). The high-CHO diet and glucose ingestion during exercise separately increased the %En from CHO oxidation in both men (+12%) and women (+24%), and the sex difference observed in the control situation disappeared. However, the increase in the %En from total CHO oxidation observed when glucose was ingested during exercise and when combined with a high-CHO diet was larger in women than in men (+47 vs +17 %En). This was not attributable to a higher %En from exogenous glucose oxidation in women, for which no sex difference was observed (25 and 27 %En in men and women), but was attributable to a smaller decrease in endogenous glucose oxidation. No significant difference in fuel selection was observed between W+OC and W-OC.

    Conclusions: The increase in total CHO oxidation after the high-CHO diet was not different between sexes. Glucose ingestion during exercise, separately and combined to the high-CHO diet, had a greater effect in women than in men; this was mostly attributable to the smaller reduction in endogenous CHO oxidation.