Background: Many papers showed that long-lasting exposure to hypobaric hypoxia changed the metabolic cost of work and substrate contribution, elevating exercise energy expenditure and carbohydrates utilization. Only few of them have shown how long this adaptive changes are maintained. The aim of the study was to assess the impact of prolonged sojourn at high altitude on the physiological cost of sub-maximal work performed at the sea level.Material/Methods: Eight members of two high altitude expeditions (Lenin Peak 7,134 m a.s.l. and Somoni Peak 7,495m a.s.l.), 7 males and 1 female, mean age 26 (±4.1) years, volunteered for this study. Aerobic performance was measured by a direct method (breath-by-breath) using an expiratory gas analyser (Oxycon Pro, Jaeger) with an incremental exercise test till exhaustion. The sea level examinations were performed 7 days before the expedition (BEx) and 7 days after (AEx) the last day at over 2,500m a.s.l. Participants spent 32 (±3) days over 2,500m a.s.l. at the mean altitude of 4,712m a.s.l. (±499m).Results: Prolonged sojourn at high altitude has changed the ventilatory parameters of sub-maximal work measured at the sea level. The sojourn resulted in an increase in the ventilatory volume (tidal volume, minute ventilation and breath frequency) during the sub-maximal work performed with the same workload. However, the respiratory exchange ratio remained at a high level compared to the baseline.Conclusions: We suggest that the adaptive changes introduced during the sojourn remain at the sea level and cause increased carbohydrate metabolism.
Introduction: Changes in blood coagulation during exposure to high altitude are not well understood and studies of activation and consumption of specific coagulation factors in hypoxic humans have yielded conflicting results. In this study we used thrombelastometry (TEM) which allows a global evaluation of clot formation and lysis process to study blood coagulation profiles in volunteers exposed to prolonged hypobaric hypoxia at extreme altitudes.Material and methods: We conducted a prospective observational study in 39 healthy volunteers during a research expedition up to an altitude of 7050 m. Plasma based thrombelastometric measurements and standard coagulation parameters were performed at different altitudes. Results: TEM measurements showed an increase in clotting time (CT) and maximum clot firmness (MCF) at high altitudes, paralleled by an increase in international normalized ratio (INR) and activated partial thromboplastin time (aPTT). Fibrinogen concentration increased until 6022 m. D-Dimer and Thrombin-Antithrombin complex (TAT) increased with time exposed to severe hypoxia. For both measurements high-est levels were found at 4844 m after acclimatization; in contrast, lower values were observed again at 7050m in the group of summiteers. Activated protein C resistance (APC-R) was slightly lowered at all altitudes. Conclusion: Our results suggest that activation of the coagulation and fibrinolytic system occurs with increasing hypobaric hypoxia with concurrent use of coagulation factors indicating the occurrence of a consumption-coagulopathy phenotype.
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