Seasonal variability of primary schoolchildren's anthropometric indicators (the Moscow region)

Introduction. Monitoring biomedical studies indicate a pronounced seasonal variability in body weight and body mass index (BMI) in children and adolescents. However, there is no ambiguity in describing the dynamics of these changes. Several researchers have reported a predominant increase in BMI in winter, on the other hand, a number of studies have found an increase in BMI during summer holidays. The aim of this study is to assess the dynamics of seasonal changes in the following physical development indicators of primary schoolchildren in the Moscow region: body height and weight, BMI, and hand grip strength. Materials and Methods. 214 schoolchildren from the 1st to the 5th grades were annually examined in late September - early October and late March - early April. The study used such data as body height and weight, BMI, and hand grip strength. Results. The current research found a pronounced seasonal variability in primary schoolchildren’s body weight and BMI with an increase in the winter period. BMI variability is characteristic of both girls and boys, and does not depend on school entry age (between 7 and 8 years). At the same time, the number of obese children among first-graders matched the estimates reported by the WHO for the corresponding age and sex groups. The current study did not find the growth of obesity among schoolchildren until the end of the 5th grade. However, the research revealed an increase in the number of overweight children and a decrease in the number of children with normal BMI during the period between the 1st and the 5th grades. Seasonal variability in indicators of hand grip strength, as well as physical performance tests was not found. Conclusions. The data obtained allow to assume that the examined sample of children in terms of anthropometry can be considered as normal. Moreover, the existing negative trends in increasing the number of overweight children can be overcome.