The relationship between the dynamics of primary schoolchildren's physical development and the amount of screen time

Introduction. The means and methods of computerized learning, introduced in recent years in the education system, can potentially have an indirect effect on various indicators of children's health, in particular, indicators of physical development that are sensitive not only to biological, but also to social factors. The aim of this research is to study age-related dynamics of the physical development (body mass index) and its seasonal variability in elementary school students depending on the amount of screen time. Materials and Methods. The sample consisted of 4525 primary schoolchildren in grades 1-4 from 66 educational settings in Moscow. The study was conducted during 5 school years each autumn (October) and spring (March-April). All samples were independent. The study involved body weight and height assessment and BMI (kg/m2) calculation. The amount of school-based and out-of-school screen time was evaluated by teachers, according to the Hygiene standards of the Russian Federation: 0 - no screen time, 1 - the screen time meets hygiene standards requirements, 2 - the screen time is twice longer than recommended, 3 - the screen time is three or more times longer than recommended. Statistical data processing was performed using nonparametric criteria. Results. The research found a correlation between the amount of out-of-school computer screen time and BMI in primary schoolchildren. The relationship between the amount of school-based screen time and BMI has not been identified. Boys are more likely to respond to an increase in out-of-school screen time. The boys' body response to a high level of out-of-school screen time is an increase in BMI and a change in its seasonal variability (from an increase during the winter period to a significant increase during the summer period). Conclusions. The study reveals the correlation between the amount of out-of-school screen time and physical development of primary schoolchildren. The authors suppose that the most likely reason for the increase in BMI and changes in its seasonal dynamics in the context of digitalization and computerization of education is a forced decrease in children's motor activity.