[Age and gender peculiarities of body composition in pupils according to bioelectrical impedance analysis].

The study is relevant due to insufficient diagnostic sensitivity of the body mass index to assess the risk of nutrition disorders and determine the range and the content of preventive measures. The aim of the research was to investigate age and gender characteristics of body composition indicators in schoolchildren according to bioimpedance analysis. Material and methods. 136 students of the city secondary school divided in four age groups (7-8, 10-11, 12-14, 15-17 years old) were examined, each group was divided into gender subgroups. All children underwent bio-impedance research using the analyzer ABC-01 «Medass». A comparative analysis of anthropometric data, absolute and relative average values of the main parameters of bio-impedance analysis and the frequency of deviation of the parameter from standard values was carried out. Results and discussion. Boys in the age group of 7-8 years showed a tendency to more frequent registration of both deficiency and excess body fat relative to girls (36 vs 8% and 36 vs 15%). The body composition of girls in this age group was characterized by higher values of the indicators of the development of musculoskeletal system. Children aged 10-11 years, demonstrated less sexual differentiation between indicators of fat metabolism; adipose tissue deficiency was detected with a frequency up to 13-20%, an excess - up to 40-47%. Girls were also characterized by higher parameters of skeletal muscle mass. In boys of the 12-14 year old age group, the average values of the phase angle, active cell mass and its proportion were statistically significantly lower than the similar indicators for girls. The most pronounced gender differences were found in children in the age group of 15-17 years. The average height and body weight of boys exceeded that of girls. The average values of the phase angle, lean mass, active cell mass, musculoskeletal mass and their proportion were statistically significantly higher in boys, against the background of lower parameters of fat metabolism relative to similar indicators of girls. A direct relationship of age with the proportion of skeletal muscle mass and the relative value of active cell mass in boys, and the proportion of fat mass in girls has been shown. It is noteworthy that the frequency of high values of the proportion of fat mass was up to 2.2 fold higher than the percentage of high values of the body mass index. Conclusion. In boys in the period from 7 to 17 years, there was observed an increase in indicators characterizing the level of motor activity and overall physical development, and in girls the prevalence of the adipose tissue excess and obesity increased.