Petryk K. Autonomic dysfunction in primary school children with overweight.

The thesis is devoted to the study of the relationship between the functional state of the autonomic nervous system and indicators of body composition in the overweight primary school children and the clarifying of the possibility of correcting autonomic dysfunction by adjusting their lifestyle. The first chapter contains a detailed review of the literature on the topic of the dissertation, and the second chapter describes the contingent of children involved in the survey, the design and methods of the study. In particular, the methodology for analyzing heart rate variability, which is used to assess the functional state of the autonomic nervous system and the adaptive and compensatory capabilities of the body, is described in detail. The third and fourth chapters describe the results of the authors' own studies of the relationship between indicators of the functional state of the autonomic nervous system and indicators of body composition in overweight children and in children of the control group with body weight within the physiological norm, as well as the results of a physiological experiment involving 44 overweight children aged 9 to 11 years. The results of this experiment convincingly demonstrate that weight loss and physical activity can improve the functional state of the autonomic nervous system in overweight children. Chapter five is devoted to a discussion of the research results obtained in the previous chapters, comparing them with the data of other authors, and analyzing possible areas of practical application of these results. The scientific novelty of the results obtained is that in primary school children the indicators of the functional state of the ANS, assessed by heart rate variability, significantly depend on body mass index and parameters of body composition - total fat content, visceral fat rating and lean mass content. Using correlation and regression analysis, it was first established that the absolute values of HRV spectral parameters cannot be considered a reliable marker of autonomic dysfunction in overweight and obese children. Instead, more informative criteria for functional disorders of the ANS are the percentage indicators of the energy structure of the heart rhythm - HF%, LF%, VLF% and PARS. Key words: types of autonomic nervous regulation, autonomic nervous system, heart rate variability, body composition, autonomic dysfunction, primary school children.