| Abstrakt: |
The aim of this work was to study the indicators of heart rate variability (HRV) under conditions of additional respiratory resistance (ARR) as a simulation of climbing to a height in young men with different types of autonomic regulation. The study involved 715 young men aged 19 to 24 years. HRV parameters were assessed by the method of variational pulsometry (BioMouse). Each subject underwent two tests lasting 5 min: background and under ARR conditions. An ETM 2.0 resistive mask was used to simulate climbing (ARR simulation) in three altitudes: 3000, 9000, and 18 000 feet. Each person performed only one test; the height of the lift was not reported to him. Based on the results of background testing, two groups were created: the optimal balance (OB) group—with balanced sympathetic and parasympathetic influences on HRV (stress index 25–100 c.u., VLF above 240 ms2) and the parasympathetic tone (PT) group—with a moderate predominance of parasympathetic (vagal) influences (stress index below 25 c.u., VLF above 500 ms2). During background testing, the OB group was characterized by higher values of the Baevsky indices (the vegetative balance index VBI, vegetative rhythm index VRI, and the indicator of the adequacy of regulatory processes ARPs) reflecting the predominance of sympathetic tone, and the PT group had higher values of the variational range of the duration of R–R intervals, RMSSD, SDNN, and pNN50%, which are considered markers of increased vagal tone, and the total power (TP) of the HRV spectrum. Under ARR conditions, without taking into account the height of the simulated rise, in the OB group, an increase in indicators correlating with vagal activity was revealed: the range of R–R intervals, RMSSD, SDNN, the HF band in the HRV spectrum, with a decrease in the Baevsky indices (VBI, VRI, ARP, and stress index). The increase in spectral measures of HRV associated with sympathetic activity (LF%) and TP reached the statistical significance level only when simulating an ascent to an altitude of 18 000 feet. In the PT group, the changes were oppositely directed: a decrease in correlates of vagal activity and an increase in sympathetic tone, regardless of the height of the lift. However, in both groups, the range of R–R intervals increased most at an altitude of 9000 feet, which is critical for the development of mountain sickness. Differences in the autonomic regulation of the cardiovascular system in young men determine the direction and severity of shifts in HRV indicators when simulating a rise to a height. In the OB group under ARR conditions, the indicators associated with vagal activity increase when a rise to insignificant heights was simulated; with an increase in the rise height, the parameters reflecting the sympathetic tone also increase. In the PT group, an expected increase in sympathetic tone was found at all altitudes. [ABSTRACT FROM AUTHOR] |
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