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Département de Physiologie, Centre Médical Universitaire, 1211 Geneva 4; Anatomisches Institut, Universität Bern, 1000 Berne, Switzerland; Unité de Recherche Associé 1341, Centre National de la Recherche Scientifique, Laboratoire de Physiologie, Université Claude Bernard, 69373 Lyon Cedex 08, France; and Instituto Boliviano de Biología de Altura, Universidad Mayor de San Andrés, Casilla 717, La Paz, Bolivia
Received 12 March 1996; accepted in final form 23 July 1996.
Kayser, Bengt, Roland Favier, Guido Ferretti, Dominique
Desplanches, Hilde Spielvogel, Harry Koubi, Brigitte Sempore, and Hans
Hoppeler. Lactate and epinephrine during exercise in altitude
natives. J. Appl. Physiol. 81(6):
2488-2494, 1996.
We tested the hypothesis that the reported low
blood lactate accumulation ([La]) during exercise in
altitude-native humans is refractory to hypoxia-normoxia transitions by
investigating whether acute changes in inspired
O2 fraction
(FIO2) affect the
[La] vs. power output (
)
relationship or, alternatively, as reported for lowlanders, whether
changes in [La] vs.
on changes in
FIO2 are related to
changes in blood epinephrine concentration ([Epi]). Altitude natives [n = 8, age 24 ± 1 (SE) yr, body mass 62 ± 3 kg, height 167 ± 2 cm]
in La Paz, Bolivia (3,600 m) performed incremental exercise with two
legs and one leg in chronic hypoxia and acute normoxia (AN). Submaximal
one- and two-leg O2 uptake (
O2) vs.
relationships were not altered by
FIO2. AN increased two-leg
peak
O2 by 10% and peak
by 7%. AN paradoxically decreased
one-leg peak
O2 by 7%,
whereas peak
remained the same. The
[La] vs.
relationships were similar to
those reported in unacclimatized lowlanders. There was a shift to the
right on AN, and maximum [La] was reduced by 7 and 8% for
one- and two-leg exercises, respectively. [Epi] and
[La] were tightly related (mean r = 0.81) independently of
FIO2. Thus normoxia
attenuated the increment in both [La] and [Epi]
as a function of
, whereas the correlation between
[La] and [Epi] was unaffected. These data suggest loose linkage of glycolysis to oxidative phosphorylation under influence from [Epi]. In conclusion, high-altitude
natives appear to be not fundamentally different from lowlanders with regard to the effect of acute changes in
FIO2 on [La] during exercise.
lactate paradox; energetics
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