preprints.org > public health and healthcare > public, environmental and occupational health > doi: 10.20944/preprints202407.1243.v1 (registering DOI)

Preprint Article Version 1 This version is not peer-reviewed

Version 1 : Received: 12 July 2024 / Approved: 15 July 2024 / Online: 17 July 2024 (04:30:34 CEST)

Background: Chronic exposure to severe hypoxia causes an increase in hematocrit (Hct) and hemoglobin concentration ([Hb]), which can lead to Excessive Erythrocytosis (EE), which could impact physical performance. This work aims to determine the differences in the six-minute walking test (6MWT) outputs between EE and healthy subjects residing at more than 5000 meters. Methods: A prospective, cross-sectional study was performed on 71 men (36 healthy and 25 suffering EE) living in La Rinconada, Peru (5100 m). Basal levels of [Hb] and Hct were obtained. All the subjects per-formed the 6MWT, and distance reached, vital signs, dyspnea, and fatigue (Borg scale) at the end of the test were recorded. Results: The average [Hb] and Hct levels in the control group were 18.7 ± 1.2 g/dL and 60.4 ± 7.1%, respectively, contrasting with EE subjects who showed 23.4 ± 1.6 g/dL and 73.6 ± 5.9% (p < 0.001). However, no statistically significant differences were observed in BMI or other anthropometric parameters. At the end of the 6MWT, the distance traveled, and vital constants were similar between both groups, except for arterial oxygen saturation which was consistently lower in subjects with EE along the test. Conclusion: EE does not significantly affect 6MWT performance at high altitudes nor the hemodynamic control during moderate aerobic exercise of subjects who live permanently in a severe hypoxic environment.

excessive erythrocytosis; high-altitude native; La Rinconada; Andes; six-minute walking test; physical performance; hypobaric hypoxia; chronic mountain sickness; hemoglobin; hematocrit

Public Health and Healthcare, Public, Environmental and Occupational Health

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