Effect of carbohydrate ingestion on glucose kinetics during exercise in the heat
Data(s) |
01/02/2001
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Resumo |
Six endurance-trained men [peak oxygen uptake (VO<sub>2</sub>) = 4.58 ± 0.50 (SE) l/min] completed 60 min of exercise at a workload requiring 68 ± 2% peak VO<sub>2</sub> in an environmental chamber maintained at 35°C (<50% relative humidity) on two occasions, separated by at least 1 wk. Subjects ingested either a 6% glucose solution containing 1 µCi [3-<sup>3</sup>H]glucose/g glucose (CHO trial) or a sweet placebo (Con trial) during the trials. Rates of hepatic glucose production [HGP = glucose rate of appearance (R<sub>a</sub>) in Con trial] and glucose disappearance (R<sub>d</sub>), were measured using a primed, continuous infusion of [6,6-<sup><sub>2</sub></sup>H]glucose, corrected for gut-derived glucose (gut R<sub>a</sub>) in the CHO trial. No differences in heart rate, VO<sub>2</sub>, respiratory exchange ratio, or rectal temperature were observed between trials. Plasma glucose concentrations were similar at rest but increased (<i>P</i> < 0.05) to a greater extent in the CHO trial compared with the Con trial. This was due to the absorption of ingested glucose in the CHO trial, because gut R<sub>a</sub> after 30 and 50 min (16 ± 5 µmol · kg<sup>-1</sup> · min<sup>-1</sup>) was higher (<i>P</i> < 0.05) compared with rest, whereas HGP during exercise was not different between trials. Glucose R<sub>d</sub> was higher (<i>P</i> < 0.05) in the CHO trial after 30 and 50 min (48.0 ± 6.3 vs 34.6 ± 3.8 µmol · kg<sup>-1</sup> · min<sup>-1</sup>, CHO vs. Con, respectively). These results indicate that ingestion of carbohydrate, at a rate of ~1.0 g/min, increases glucose Rd but does not blunt the rise in HGP during exercise in the heat. <br /> |
Identificador | |
Idioma(s) |
eng |
Publicador |
American Physiological Society |
Relação |
http://dro.deakin.edu.au/eserv/DU:30008397/n20010422.pdf http://jap.physiology.org/cgi/content/abstract/90/2/601?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&andorexactfulltext=and&searchid=1&FIRSTINDEX=0&sortspec=relevance&volume=90&firstpage=601&resourcetype=HWCIT |
Direitos |
2001, American Physiological Society |
Palavras-Chave | #heat stress #liver glucose output #muscle glucose uptake |
Tipo |
Journal Article |