MUSCLE-TISSUE ADAPTATIONS OF HIGH-ALTITUDE NATIVES TO TRAINING IN CHRONIC HYPOXIA OR ACUTE NORMOXIA

Citation
D. Desplanches et al., MUSCLE-TISSUE ADAPTATIONS OF HIGH-ALTITUDE NATIVES TO TRAINING IN CHRONIC HYPOXIA OR ACUTE NORMOXIA, Journal of applied physiology, 81(5), 1996, pp. 1946-1951
Citations number
33
Categorie Soggetti
Physiology,"Sport Sciences
ISSN journal
87507587
Volume
81
Issue
5
Year of publication
1996
Pages
1946 - 1951
Database
ISI
SICI code
8750-7587(1996)81:5<1946:MAOHNT>2.0.ZU;2-Z
Abstract
Twenty healthy high-altitude natives, residents of La Pat, Bolivia (3, 600 m), participated in 6 wk of endurance exercise training on bicycle ergometers, 5 times/wk, 30 min/session, as previously described in no rmoxia-trained sea-level natives (K. Hoppeler, H. Howald, K. E. Conley , S. L. Lindstedt, H. Claassen, P. Vock, and E. R. Weibel. J. Appl. Ph ysiol. 59: 320-327, 1985). A first group of 10 subjects was trained in chronic hypoxia (HT barometric pressure = 500 mmHg; inspired O-2 frac tion = 0.209) a second group of 10 subjects was trained in acute normo xia (NT; barometric pressure = 500 mmHg; inspired O-2 fraction = 0.314 ). The workloads were adjusted to similar to 70% of peak O-2 consumpti on (Vo(2)peak) measured either in hypoxia for the HT group or in normo xia for the NT group. Vo(2peak) determination and biopsies of the vast us lateralis muscle were taken before and after the training program. Vo(2peak) in the HT group was increased (14%) in a way similar to that in NT sea-level natives with the same protocol. Moreover, Vo(2peak) i n the NT group was not further increased by additional Oz delivery dur ing the training session. HT or NT induced similar increases in muscle capillary-to-fiber ratio (26%) and capillary density (19%) as well as in the volume density of total mitochondria and citrate synthase acti vity (45%). It is concluded that high-altitude natives have a reduced capillarity and muscle tissue oxidative capacity; however, their train ing response is similar to that of sea-level residents, independent of whether training is carried out in hypobaric hypoxia or hypobaric nor moxia.