Relationships between active school transport and adiposity indicators in school-age children from low-, middle- and high-income countries

OBJECTIVES: Within the global context of the nutrition and physical activity transition it is important to determine the relationship between adiposity and active school transport (AST) across different environmental and socio-cultural settings. The present study assessed the association between adiposity (that is, body mass index z-score (BMIz), obesity, percentage body fat (PBF), waist circumference) and AST in 12 country sites, in the International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE). METHODS: The analytical sample included 6797 children aged 9-11 years. Adiposity indicators included, BMIz calculated using reference data from the World Health Organization, obesity (BMIz ≥ +2 s.d.), PBF measured using bioelectrical impedance and waist circumference. School travel mode was assessed by questionnaire and categorized as active travel versus motorized travel. Multilevel linear and non-linear models were used to estimate the magnitude of the associations between adiposity indicators and AST by country site and sex. RESULTS: After adjusting for age, sex, parental education and motorized vehicle availability, children who reported AST were less likely to be obese (odds ratio = 0.72, 95% confidence interval (0.60-0.87), Po0.001) and had a lower BMIz (-0.09, s.e.m. = 0.04, P = 0.013), PBF (least square means (LSM) 20.57 versus 21.23% difference - 0.66, s.e.m. = 0.22, P = 0.002) and waist circumference (LSM 63.73 cm versus 64.63 cm difference - 0.90, s.e.m. = 0.26, P=0.001) compared with those who reported motorized travel. Overall, associations between obesity and AST did not differ by country (P = 0.279) or by sex (P = 0.571). CONCLUSIONS: AST was associated with lower measures of adiposity in this multinational sample of children. Such findings could inform global efforts to prevent obesity among school-age children.