Relationship of mountain sickness to physical fitness and exercise intensity during ascent

Abstract

The purpose of the study was to investigate whether susceptibility to acute mountain sickness (AMS) and high-altitude pulmonary edema (HAPE) is related to differences of physical fitness and /or the level of exercise during ascent. Work capacity at a heart rate of 170 min⁻¹ (PWC₁₇₀) was assessed on a bicycle ergometer prior to high-altitude exposure, and the heart rate was continuously registered during the ascent from 3610 to 4559 m in 41 mountaineers. During the subsequent stay of 3 days at 4559 m, 12 subjects developed AMS, 13 subjects showed radiographic evidence of HAPE, and 16 subjects remained without significant illness. PWC₁₇₀ (group means between 238 and 247 W) and heart rate during ascent (group means between 134 and 141 min⁻¹) did not significantly differ between these groups. PWC₁₇₀ correlated negatively with two independent symptoms scores (clinical score, environmental symptom questionnaire) on day 3 at 4559 m, whereas heart rate during ascent correlated positively only with clinical score on days 2 and 3 at 4559 m. Correlations, however, were minor, with correlation coefficients of r = 0.32–0.43 (p < 0.05–0.01). These results indicate that physical fitness or exercise intensity during ascent were of minor importance for the development of AMS and HAPE in our subjects.