Muscle tissue adaptations of high-altitude natives to training in
chronic hypoxia or acute normoxia.
Desplanches, D., H. Hoppeler, L. Tuscher, M. H. Mayet, H. Spielvogel,
G. Ferretti, B. Kayser, M. Leuenberger, A. Grunenfelder, R. Favier.
UMR 5578 CNRS, Laboratoire de Physiologie, Facult_ de M_decine, F
-69373 Lyon Cedex 08, Lyon, France, Anatomisches Institut, UniversitSt
Bern, CH- 3000 Bern, Switzerland, Instituto Boliviano de Biologia de
Altura, La Paz, Bolivia
APStracts 3:0351A, 1996.
Twenty healthy high-altitude natives, residents from La Paz (Bolivia,
3600m) participated in 6 weeks of endurance exercise training on
bicycle ergometers, 5 times a week, 30 min/session, as previously
described in normoxia-trained sea-level natives (Hoppeler et al., J.
Appl. Physiol., 59 : 320-327, 1985). A first group of 10 subjects
(Hyp T) was trained in chronic hypoxia (PB [angstrom]a 500 mm Hg, F i
O2 = 0.209), a second group of ten subjects (Nor T) in acute normoxia
(PB [angstrom]a 500 mm Hg, F i O2 = 0.314). The workloads were
adjusted to approximately 70 % VO 2peak either measured in hypoxia
for the Hyp T group or in normoxia for the Nor T group. Peak oxygen
consumption (VO 2peak ) determination and biopsies of vastus
lateralis muscle were taken before and after the training program. VO
2peak in Hyp T group was increased in a similar way (+ 14 %) than in
normoxia-trained sea-level natives with the same protocol. Moreover,
VO 2peak in Nor T was not further increased by additional O2 delivery
during the training session. Hyp T or Nor T induced similar increases
in muscle capillary per fiber ratio (+ 26 %) and capillary density (+
19 %) as well as in the volume density of total mitochondria and
citrate synthase activity (+ 45 %). It is concluded that high
-altitude natives have a reduced capillarity and muscle tissue
oxidative capacity, however, their training response is similar to
that of sea-level residents, independent of whether training is
carried out in hypobaric hypoxia or hypobaric normoxia.
Received 26 December 1995; accepted in final form 17 July 1996.
APS Manuscript Number A1341-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 4 August 1996