RESUMO
The isottonic work perfomance was assessed in 34 workers aged 35 ñ 5.8 years old that had working of four days at 4500 m over the sea level and resting periods of other four days at the sea level during at least two years. Subjects were assessed in one occasion at the sea level, and at the first and fourth day of the working shift at 4500 m over the sea level. resting arterial oxygen saturation in theses three periods was 97 ñ 1.1, 88 ñ 18 and 91 ñ 1.1 percent respectively (p<0.01) and markedly decreased during maximal and submaximal exercise at 4500 m over sea level. Evercise duration in the three periods was 931 ñ 210, 775 ñ 105 and 778 ñ 105 seg respectively (p<0.001). Heart rate in the resting period was at least 10 percent higher and maximal and submaxilmal rates were lower at the high altitude. No differences in blood pressure or packed red cell volume were observed. Exercise duration correlated inversely with age (r=-0.49 p=0.03) and directly with maximal heart rate (r=0.44 p=0.009) at the sea level. No correlation between aerobic capacity and other measured parameters was observed. These results show no differences in the cardiovascular response to exercise between the first and fourth day of stay at high altitude in workers chronically exposed to intermittent hypobaric hypoxia
