Abstract
Frequency of therapeutic β-blocker use in elderly mountaineers is unknown. Therefore, the aim of this field study was to measure the regular β-blocker intake in elderly persons visiting moderate altitudes. In a subset of mountaineers on β-blockers, exercise response at two different altitude levels was compared to matched controls. The observed frequency of β-blocked persons among the interviewed elderly mountaineers (age >35) was 7%, mainly (65%) due to hypertension. In subjects taking β-blockers, arterial oxygen saturation (84 ± 6% vs. 90 ± 3%, p < 0.05) was decreased and heart rate (120 ± 17 bpm vs. 112 ± 14 bpm, p = 0.01), rate pressure product (22,192 ± 6459 vs. 17,576 ± 4010, p < 0.05), and ratings of perceived exertion (14 ± 3 vs. 12 ± 3, p < 0.05) were increased during a submaximal step test at 2311 m compared to 1480 m. Mountaineers without β-blocker intake showed no changes. Although the epidemiological data have to be interpreted with caution because of the small sample size and the limitation to a single geographical site, a large number of β-blocked persons visiting high altitudes was observed. If confirmed in further studies, the increased heart work and exertion could indicate a reduced exercise tolerance of people taking β-blockers during acute high altitude exposure.
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