TY - JOUR
T1 - Carbohydrate ingestion can completely suppress endogenous glucose production during exercise.
AU - Jeukendrup, A.E.
AU - Wagenmakers, A.J.M.
AU - Stegen, J.H.C.H.
AU - Gijsen, A.P.
AU - Brouns, F.J.P.H.
AU - Saris, W.H.M.
PY - 1999/1/1
Y1 - 1999/1/1
N2 - The purposes of this study were 1) to investigate the effect of carbohydrate (CHO) ingestion on endogenous glucose production (EGP) during prolonged exercise, 2) to study whether glucose appearance in the circulation could be a limiting factor for exogenous CHO oxidation, and 3) to, investigate whether large CHO feedings can reduce muscle glycogen oxidation during exercise. Six well-trained subjects exercised three times for 120 min at 50% maximum workload while ingesting water (FAST), a 4% glucose solution (LO-Glc), or a 22% glucose solution (HI-Glc). A primed continuous intravenous [6,6-H-2(2)]glucose infusion was given, and the ingested glucose was enriched with [U-C-13]glucose. Glucose ingestion significantly elevated CHO oxidation as well as the rates of appearance (R-a) and disappearance. R-a glucose equaled R-a of glucose in gut (R-a gut) during HI-Glc, whereas EGP was completely suppressed. During LO-Glc, EGP was partially suppressed, whereas R-a gut provided most of the total glucose R-a. We conclude that 1) high rates of CHO ingestion can completely block EGP, 2) R-a gut may be a limiting factor for exogenous CHO oxidation, and 3) muscle glycogen oxidation was not reduced by large glucose feedings.
AB - The purposes of this study were 1) to investigate the effect of carbohydrate (CHO) ingestion on endogenous glucose production (EGP) during prolonged exercise, 2) to study whether glucose appearance in the circulation could be a limiting factor for exogenous CHO oxidation, and 3) to, investigate whether large CHO feedings can reduce muscle glycogen oxidation during exercise. Six well-trained subjects exercised three times for 120 min at 50% maximum workload while ingesting water (FAST), a 4% glucose solution (LO-Glc), or a 22% glucose solution (HI-Glc). A primed continuous intravenous [6,6-H-2(2)]glucose infusion was given, and the ingested glucose was enriched with [U-C-13]glucose. Glucose ingestion significantly elevated CHO oxidation as well as the rates of appearance (R-a) and disappearance. R-a glucose equaled R-a of glucose in gut (R-a gut) during HI-Glc, whereas EGP was completely suppressed. During LO-Glc, EGP was partially suppressed, whereas R-a gut provided most of the total glucose R-a. We conclude that 1) high rates of CHO ingestion can completely block EGP, 2) R-a gut may be a limiting factor for exogenous CHO oxidation, and 3) muscle glycogen oxidation was not reduced by large glucose feedings.
U2 - 10.1152/AJPENDO.1999.276.4.E672
DO - 10.1152/AJPENDO.1999.276.4.E672
M3 - Article
SN - 0002-9513
VL - 276
SP - E672-E683
JO - American Journal of Physiology (Consolidated)
JF - American Journal of Physiology (Consolidated)
IS - 4 Pt 1
ER -