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Preexercise carbohydrate ingestion, glucose kinetics, and muscle glycogen use: Effect of the glycemic index

Version 2 2024-06-03, 10:12
Version 1 2021-10-20, 08:42
journal contribution
posted on 2024-06-03, 10:12 authored by MA Febbraio, J Keenan, DJ Angus, SE Campbell, Andrew GarnhamAndrew Garnham
Eight trained men cycled at 70% peak oxygen uptake for 120 min followed by a 30-min performance cycle after ingesting either a high-glycemic index (HGI), low-glycemic index (LGI), or placebo (Con) meal 30 min before exercise. Ingestion of HGI resulted in an elevated ( P < 0.01) blood glucose concentration compared with LGI and Con. At the onset of exercise, blood glucose fell ( P < 0.05) such that it was lower ( P < 0.05) in HGI compared with LGI and Con at 15 and 30 min during exercise. Plasma insulin concentration was higher ( P < 0.01) throughout the rest period after ingestion of HGI compared with LGI and Con. Plasma free fatty acid concentrations were lower ( P < 0.05) throughout exercise in HGI compared with LGI and Con. The rates of [6,6-2H]glucose appearance and disappearance were higher ( P < 0.05) at rest after ingestion and throughout exercise in HGI compared with LGI and Con. Carbohydrate oxidation was higher ( P < 0.05) throughout exercise, whereas glycogen use tended ( P = 0.07) to be higher in HGI compared with LGI and Con. No differences were observed in work output during the performance cycle when comparing the three trials. These results demonstrate that preexercise carbohydrate feeding with a HGI, but not a LGI, meal augments carbohydrate utilization during exercise but does not effect exercise performance.

History

Journal

Journal of Applied Physiology

Volume

89

Pagination

1845-1851

Location

United States

ISSN

8750-7587

eISSN

1522-1601

Language

en

Publication classification

C1.1 Refereed article in a scholarly journal

Issue

5

Publisher

American Physiological Society

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