EFFECTS OF LONG-TERM ACCLIMATIZATION IN LOWLANDERS MIGRATING TO HIGH-ALTITUDE - COMPARISON WITH HIGH-ALTITUDE RESIDENTS

The physiological response to submaximal and maximal exercise was asse ssed in lowlanders and Tibetans at low (500 m above sea level) and hig h altitude (HA, 3 680 m). The times spent at HA by the lowland migrato rs was 8 days (n = 60), 7 months (n = 60, same group), 15 months (n = 29) and 27 months (n = 29). After the 15-month stay at HA, the maximal oxygen uptake (VO2max) and maximal heart rate of the lowland migrator s almost reached those of the HA native residents (Tibetans, n = 57), but their total work capacity and the gross efficiency (eta) of mechan ical work remained lower than those of the Tibetans. The rate of VO2ma x achieved at 90 W by the Tibetans was lower than that of the lowland migrators. It was concluded that, at HA, the lowlanders regained much of the aerobic capacity which they had lost initially. However, they d id not attain the same gross mechanical efficiency as the Tibetans, wh o seemed to be at an advantage in respect of work at HA.