Hormonal and metabolic adjustments during exercise in hypoxia or
normoxia in highland natives.
Favier, R., D. Desplanches, H. Hoppeler, E. Caceres, A. Egrunenfelder,
H. Koubi, M. Leuenberger, B. Sempore, L. Etscher, and H. Spielvogel.
Instituto Boliviano de Biologia de Altura, Casilla 717, La Paz,
Bolivia, Unit de Recherches Associe 1341 Centre National de la
Recherche Scientifique, Laboratoire de Physiologie, 8 Avenue
Rockefeller, 69373 Lyon Cedex 08, France, Anatomisches Institut,
UniversitSt Bern, 3000 Bern 9, Switzerland
APStracts 2:0503A, 1995.
In sea level natives, exposure to hypoxia for a few weeks is
characterized by an increased dependence on blood glucose and a
decreased reliance on lactate for energy metabolism during exercise.
These metabolic adjustments have been attributed to behavioral
changes in the sympathoadrenergic and pancreatic systems. The aim of
this study was to test the hypothesis of a reduced sympathoadrenergic
activation and subsequent metabolic changes when high altitude
natives are acutely exposed to normoxia. Young Andean natives
performed incremental exercise to exhaustion during hypoxia (H; PaO2
= 55.1+/- 1.1 torr) or during acute normoxia (N; PaO2 = 78.7 +/- 1.7
torr). As a whole, oxygen uptake (VO2) was increased in normoxia as
compared to hypoxia during graded exercise. This finding is not
related to a decrease in anaerobic metabolism but is rather
interpreted as a consequence of a shift in substrate utilization
during exercise (increased contribution of fat as assessed by a
reduction in respiratory exchange ratio ). These metabolic changes
are not accompanied by modifications of glucoregulatory hormones
(catecholamines, insulin, glucagon). In particular, the exercise
-induced catecholamine secretion was similar in chronic hypoxia and
acute normoxia. As a consequence blood lactate accumulation during
incremental exercise was similar in both conditions. It is concluded
that high altitude natives do not display any sign of a greater
sympathoadrenergic activation during chronic hypoxia and the
exercise-induced hormonal changes remained unaffected by acute
inhalation of a normoxic gas mixture.
Received 17 March 1995; accepted in final form 5 September 1995.
APS Manuscript Number A293-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95