Exogenous glucose oxidation during exercise in endurance trained
and untrained subjects.
Jeukendrup, A. E., M. Mensink, W. H. M. Saris, and A. J. M.
Wagenmakers.
Department of Human Biology, University Maastricht, P.O.Box 616,
6200 MD Maastricht, The Netherlands
APStracts 3:0523A, 1996.
To investigate the effect of training status on the fuel mixture used
during exercise with glucose ingestion 7 endurance trained cyclists
(T, VO2max 67+/-2.3 ml.kg.min-1) and 8 untrained subjects (UT, 48+/-2
ml.kg.min-1) were studied during 120 min of exercise at 60%VO2max. At
the onset of exercise, 8 ml.kg-1 of an 8% naturally enriched [13C]
-glucose solution was ingested and 2 ml.kg-1 every 20 min thereafter.
Energy expenditure was higher in T compared to UT (3404 kJ versus
2630 kJ; P<0.01). During the second hour, fat oxidation was
higher in T (37+/-2g) compared to UT (23+/-1g) while CHO oxidation
was similar (116+/-8g in T vs 114+/-4g in UT). No differences were
observed in exogenous glucose oxidation (50+/-2g in T and 45+/-3g in
UT respectively). Peak exogenous glucose oxidation rates were similar
in the two groups (0.95+/-0.07 g.min-1 in T and 0.96+/-0.03 g.min-1
in UT). It is concluded that the higher energy expenditure in T
during exercise at the same relative exercise intensity is entirely
met by a higher rate of fat oxidation without changes in the rates of
exogenous and endogenous carbohydrates.
Received 15 July 1996; accepted in final form 1 November 1996.
APS Manuscript Number A664-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996