Changes in heart rate variability as a reflection of implemented physiological mechanisms of adaptation

Aim. To investigate changes in heart rate variability in students resulting from action of mechanisms for adaptation to university studies. Materials and Methods. Heart rate variability was assessed by the means of cardiointervalography according to Baevsky in 1st/2nd year students of the technical university (n = 30; age - 17-19). Boys from the experimental group were administered Selenes+ organic compounds in accordance with guidelines of the Ministry of Health of the Russian Federation one month prior to 1-4 examination sessions. The following parameters were studied: HR, RMSSD, pNN50, Mo, MxDMn; TP, HF, LF, VLF, LF/HF; type of vegetative regulation and the indicator of activity of regulatory systems. Results. Differential indicators of heart rate variability (RMSSD and pNN50) suggested the prevailing activity of the parasympathetic nervous system in the experimental group. The same tendency was observed in MxDMn which was higher in students of the group III as compared to the control group (255.0 ± 17.92 versus 195.3 ± 20.05 ms). Stress index (SI), vice versa, was higher in the students from the control group. Power of high frequency and low frequency components of spectrum (HF, LF) was higher in students taking Selenes+. Power of the very low frequency component (VLF) of spectrum was within the normal physiological range in both groups, while the level of LF/HF was higher in the students from the group I. Values of the indicator of activity of regulatory systems suggested that most of students had a moderate functional tension. Conclusion. Students from the experimental group during the intersession period have a comparable advantage over the control group, which is attributed to Selenes+ prescribed one month prior to 1-4 examination sessions. The established fact proves the corrective effect of the modeled factor on specifics of heart rate variability and indirectly indicates the more effective realization of physiological mechanisms of adaptation to university studies.