Respiratory acclimatization and psychomotor performance during 3 weeks at 3200m

Background: The course of acclimatization at high altitude over several weeks is not extensively studied. We performed repeated physiological assessments in healthy lowlanders staying for 3 weeks at 3200m. Methods: 16 healthy volunteers (23-33y) underwent sleep studies during 1 night in Bishkek (760m), and during nights 1, 7 and 21 at Tuja-Ashu (3200m), Kyrgyzstan. Reaction time (psychomotor vigilance test), postural control (center of gravity displacement on balance board) and subjective sleep quality (visual analog scale, 0-100 with increasing quality) were assessed. Results: Compared to 760m, mean nocturnal oxygen saturation dropped in the first night at 3200m and increased subsequently. Postural control worsened over more than a week and recovered after 21 day. Reaction time and subjective sleep quality were not affected. Conclusion: In healthy lowlanders staying at 3200m respiratory acclimatization extends over at least 3 weeks. Hypoxia impairs postural control for at least one week while reaction time and subjective sleep quality are not measurably affected despite persistent mild nocturnal periodic breathing.