Exogenous carbohydrate oxidation from different carbohydrate sources during exercise.
The exogenous carbohydrate (CHO) oxidation of naturally enriched [13C]CHO sources with different solubilities was studied during cycling exercise (150 min, 60% maximum work output). Moreover, the effect of adding a 13C tracer with different physical properties than the tracee on exogenous CHO oxidation was investigated. Test solutions (28.5 ml/kg body wt) were water for control of 13C background, 15% soluble partially hydrolyzed corn starch (SOL), 15% insoluble corn starch (In-SOL), and 15% InSOL with [13C6]glucose as tracer. Both the mean and peak exogenous oxidation rates were significantly greater (P < 0.05) in the SOL trial than in the InSOL trial (mean oxidation rate, 0.84 +/- 0.21 and 0.50 +/- 0.15 g/min, respectively; peak oxidation rate, 1.10 +/- 0.18 and 0.81 +/- 0.25 g/min, respectively). The amount of the ingested CHO that was oxidized was significantly higher (P < 0.05) in the SOL trial (126 +/- 31 g) than in the InSOL trial (75 +/- 25 g). When we added an extrinsic tracer ([13C]glucose), the apparent mean and peak oxidation rates of the trial with InSOL and [13C6]glucose were significantly (P < 0.05) higher (0.91 +/- 0.30 and 1.23 +/- 0.41, respectively) than the InSOL values. These results 1) indicate that the addition of the soluble [13C]glucose tracer to an insoluble starch tracee leads to overestimation of the exogenous CHO oxidation rates and 2) suggest that soluble CHO is oxidized at a higher rate during exercise than isocaloric insoluble CHO.
Saris
W H
WH
Department of Human Biology, University of Limburg, Maastricht, The Netherlands.
Goodpaster
B H
BH
Jeukendrup
A E
AE
Brouns
F
F
Halliday
D
D
Wagenmakers
A J
AJ
D000328:Adult; D002245:Carbon Dioxide / Q000378:metabolism; D002247:Carbon Isotopes; D004040:Dietary Carbohydrates / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D007700:Kinetics; D008297:Male; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology
D002247:Carbon Isotopes; D004040:Dietary Carbohydrates; D002245:Carbon Dioxide