Cardiopulmonary and metabolic responses in healthy elderly humans during a1-week hiking programme at high altitude

Worldwide there are approximately 100 million visitors to high altitude ann ually and about 15% of those are elderly. Nevertheless, basic information o n the cardiopulmonary and metabolic responses to physical activity at high altitude in the elderly is scarce. Therefore, we studied 20 voluntary healt hy elderly subjects (55-77 years) who were randomly assigned to a low(600 m ) or a high altitude (2,000 m) group. Both groups increased the duration of their daily hiking from 2.5 to 5 h during a period of 1 week. Pre- and pos t-hiking cardiopulmonary variables at rest were measured daily. Exercise te sts (3 min step test) were performed on days 1, 4 and 7. Of the morning val ues at rest, only arterial oxygen saturation (SaO2) had decreased after the Ist night at high altitude. After hiking however, SaO2 was diminished on a ll days at high altitude. Post-hiking heart rates increased from baseline o n days 1 and 2 in the low- and on days 1-5 in the high-altitude group. Exer cising SaO2 (%) in the three tests was decreased [84.9 (SD 2.8), 88.1 (SD 2 .1), 87.2 (SD 2.3)]compared to baseline [93.2 (SD 2.0); P<0.05] and blood l actate concentrations were increased [3.1 (SD 0.7), 3.4 (SD 0.3), 3.3 (SD 0 .2)]compared to baseline [2.7 (SD 0.6); P<0.05] in all tests at high altitu de. The 1-week hiking programme was well tolerated by the healthy elderly a t both low and high altitudes. Ventilatory adaptation to high altitude in t he elderly seemed to have been completed within the first 2 days during the measurements at rest. However, cardiopulmonary and metabolic responses to exercise were increased and recovery from exercise was delayed during the 1 -week hiking programme at high altitude. Heart rate and SaO2 measurements a re considered to be highly sensitive in estimating the state of acclimatisa tion and for monitoring exercise intensity and duration at high altitude.