Response of the cardiovascular system to heart rate variability biofeedback in adolescents with different autonomic nervous tone living in northern and southern regions

Abstract

BACKGROUND: The reactions of the cardiovascular system of adolescents during self-regulation depend on the state of their initial autonomic tone and region of residence. AIM: Was to investigate the dynamics of cardiovascular system indices during heart rate variability biofeedback (HRVBF) one-time training in adolescents with different initial autonomic regulation of heart rhythm, taking into account their residence in the northern and southern regions. MATERIALS AND METHODS: Schoolchildren aged 1617 years, residents of the North-West (n=55), North-East (n=55) and South (n=55) regions of the Russian Federation were examined. Heart rate variability (HRV) and blood pressure (BP) were recorded. Participants were divided into the following groups according to their baseline autonomic regulation of cardiac rhythm: vagotonics, normotonics and sympathotonics. Normotonics and sympathotonics additionally had a one-time HRVBF session due to increase parasympathetic influences on heart rhythm. RESULTS: The northwestern/northeastern/southern samples revealed 29.1/7.3/16.4% vagotonics; 41.8/47.3/49.1% normotonics; and 29.1/45.4/34.5% sympathotonics. Significantly higher BP levels were detected in sympathotonics in the northeastern region compared to vagotonics and normotonics in this region, as well as sympathotonics in the northwestern and southern regions. HRVBF training was successful in all of its participants, HRV parameters responded significantly more strongly in sympathotonics of the northwest region, while their BP and baroreflex levels were relatively stable. Sympathotonics of the northeastern and southern regions were characterized by preservation of elevated HR after HRVBF, accompanied by a distinct vascular response (significant decrease in BP) and a pronounced baroreflex response. CONCLUSION: Sympathicotonia and increased vascular response to HRVBF are characteristic of adolescents of the North-West region, who are mostly descendants of immigrants from Southern regions. The descendants of the natives of the northwestern region apparently possess more perfect hereditary mechanisms of cardiovascular system adaptation to the conditions of living in the Arctic.