Postmarathon paradox: insulin resistance in the face of glycogen
depletion.
Tuominen, Juha A., Pertti Ebeling, Raymond Bourey, Laszlo Koranyi,
Antti Lamminen, Juhani Rapola, Timo Sane, Helena Vuorinen-Markkola,
and Veikko A. Koivisto.
Department of Medicine, Helsinki University Central Hospital, FIN
-00290 Helsinki, Finland; Washington University School of Medicine,
St. Louis, Missouri 63110, USA; Hungarian Heart Center, Department of
Metabolism, H-8231 Balatonf[umlaut]ured, Hungary; Department of
Radiology and Department of Pediatrics, Helsinki University Central
Hospital, FIN-00290 Helsinki, Finland
APStracts 2:0201E, 1995.
Acute physical exercise enhances insulin sensitivity in healthy
subjects. We examined the effect of a 42 km marathon run on insulin
sensitivity and lipid oxidation in 19 male runners. In the morning
after the marathon run, basal serum FFA concentration was 2.2-fold
higher, muscle glycogen content 37% lower (p<0.01), glycogen
synthase fractional activity 56% greater (p<0.01) and glucose
oxidation reduced by 43% (p<0.01), whereas lipid oxidation was
increased by 55% (p<0.02) as compared to the control study.
During euglycemic hyperinsulinemic clamp, whole body glucose disposal
was decreased by 12% (p<0.01) due to a 36% lower glucose
oxidation rate (p<0.05), whereas the rate of lipid oxidation was
10-fold greater (p<0.02) than in the control study. After the
marathon, muscle glycogen content correlated positively with lipid
oxidation (r=0.60, p<0.05) and VO2peak (r=0.61, p<0.05).
VO2peak correlated positively with basal lipid oxidation (r=0.57,
p<0.05). In conclusion: 1) After the marathon run, probably due
to increased lipid oxidation the insulin-stimulated glucose disposal
is decreased in spite of muscle glycogen depletion and the activation
of glycogen synthase. 2) The contribution of lipid oxidation in
energy expenditure is increased in proportion to physical fitness. 3)
These adaptations of fuel homeostasis may contribute to the
maintenance of physical performance after prolonged exercise.
Received 19 June 1995; accepted in final form 18 September 1995.
APS Manuscript Number E280-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95