Exercise performance in lowlanders with COPD travelling to 2048m

Introduction: Altitude travel in patients with COPD may be hampered by limitation in exercise performance but the extent and underlying physiological mechanisms have not been conclusively studied. Objective: To evaluate exercise performance in patients with COPD living below 600m travelling to 2048m. Methods 29 COPD patients, GOLD grade 2-3, mean±SD aged 65±6y, FEV1 59±13%pred. underwent bicycle spiroergometry with an identical ramp protocol to exhaustion at 490m (Zurich) and, within 2h after rapid ascent, at 2048m (St. Moritz). Physiological variables during the final 30sec of exercise were compared between altitudes. Results: Altitude-induced hypoxemia at 2048m reduced maximal work rate and oxygen uptake while heart rate, breathing reserve, and dyspnoea did not change (table). Conclusions: Ascent to 2048m, an altitude corresponding to that of many alpine resorts, reduced exercise performance of lowlanders with COPD only slightly. Since neither breathing nor heart rate reserve were altered, the altitude-induced performance impairment may have been due to effects of hypoxia on dyspnoea perception and muscle function rather than due to aggravated ventilatory or cardiovascular constraints. Grant: Swiss National Science Foundation, Lunge Zurich.