Why are children different in their moderate-to-vigorous physical activity levels? A multilevel analysis

Objective: Children's differences in moderate-to-vigorous physical activity levels are not at random. This study investigates the relevance of individual- and school-level characteristics in explaining these differences. Methods: In total, 307 children (154 girls) aged 5-10 years, from 19 Portuguese schools, were sampled. Height and weight were measured, and body mass index was calculated. Time spent in moderate-to-vigorous physical activity was measured by accelerometry. Gross motor coordination was assessed with the KorperkoordinationsTest fur Kinder battery and socio-economic status was obtained via the school social support system. School characteristics were obtained with an objective school audit. A multilevel analysis was used as implemented in Stata 15. Results: Schools explained 18.2% of the total variance in moderate-to-vigorous physical activity, with the remainder being ascribed to children's distinct characteristics. Boys were more active (beta= 29.59 +/- 11.52, p < 0.05), and having higher gross motor coordination levels (beta=0.11 +/- 0.04, p < 0.05) was positively associated with daily moderate-to-vigorous physical activity, whereas being older (beta= -5.00 +/- 1.57, p < 0.05) and having higher socio-economic status (beta= -7.89 +/- 3.12, p < 0.05) were negatively related with moderate-to-vigorous physical activity.From the school-level correlates, only playground dimension was significantly associated with moderate-to-vigorous physical activity levels. Children from schools with medium (40 m(2) to 69 m(2)) and large playground dimensions (>= 70m(2)) were less active than children with smaller playground dimensions (10 m(2) to 39 m(2) ). Conclusions: Variation in school children's moderate-to-vigorous physical activity is mostly explained by their individual characteristics; school characteristics also play a rote but to a smaller degree. Future intervention programs to change this behavior should be more personalized, emphasizing mostly individual-level characteristics. (C) 2018 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda.