Dynamics of Indicators of the Cardiovascular System and Its Autonomic Regulation during Overwintering in the Arctic

Most studies on the adaptation of humans to extreme conditions of the polar regions were performed in Antarctic expeditions.Our research aims to study the same parameters in the Arctic.The study was conducted at the North Pole 41 drifting polar station (NP-41) and involved 14 men.The participants were divided into two groups: "ice" -working mainly outdoors (n=8), and "laboratory"working mainly indoors (n=6).A semi-annual monitoring included assessment of the parameters of cardiac performance, heart rate variability (HRV), and blood pressure variability (BP).During the study, no significant changes were revealed in parameters of cardiac performance and HRV.In group "ice", according to the indicators of BP variability, a decrease in the pulse BP both at rest and under conditions of controlled respiration was noted during the first 3 weeks of overwintering.At later terms, no dynamics of this indicator was found.In group "laboratory", an increase in pulse BP was detected from the third week to 6 months of overwintering also at rest and under conditions of controlled respiration.The test with controlled respiration allowed us to demonstrate the contribution of the LF range power to BP change.Conclusions: the pattern of adaptive changes during overwintering in the North depends on the type of occupational activity.