Objective Measures of the Built Environment and Physical Activity in Children: From Walkability to Moveability

Features of the built environment that may influence physical activity (PA) levels are commonly captured using a so-called walkability index. Since such indices typically describe opportunities for walking in everyday life of adults, they might not be applicable to assess urban opportunities for PA in children. Particularly, the spatial availability of recreational facilities may have an impact on PA in children and should be additionally considered. We linked individual data of 400 2- to 9-year-old children recruited in the European IDEFICS study to geographic data of one German study region, based on individual network-dependent neighborhoods. Environmental features of the walkability concept and the availability of recreational facilities, i.e. playgrounds, green spaces, and parks, were measured. Relevant features were combined to a moveability index that should capture urban opportunities for PA in children. A gamma log-regression model was used to model linear and non-linear effects of individual variables on accelerometer-based moderate-to-vigorous physical activity (MVPA) stratified by pre-school children (< 6 years) and school children (>= 6 years). Single environmental features and the resulting indices were separately included into the model to investigate the effect of each variable on MVPA. In school children, commonly used features such as residential density ((beta) over cap = 0.5.10(-4); p = 0.02), intersection density ((beta) over cap = 0.003, p = 0.04), and public transit density ((beta) over cap = 0.037, p = 0.01) showed a positive effect on MVPA, while land use mix revealed a negative effect on MVPA ((beta) over cap = -0.173, p = 0.13) In particular, playground density ((beta) over cap = 0.048; p = 0.01) and density of public open spaces, i.e., playgrounds and parks combined ((beta) over cap = 0.040, p = 0.01), showed positive effects on MVPA. However, availability of green spaces showed no effect on MVPA. Different moveability indices were constructed based on the walkability index accounting for the negative impact of land use mix. Moveability indices showed also strong effects on MVPA in school children for both components, expanded by playground density ((beta) over cap = 0.014; p = 0.008) or by public open space density ((beta) over cap = 0.014, p = 0.007), but no effects of urban measures and moveability indices were found in pre-school children. The final moveability indices capture relevant opportunities for PA in school children. Particularly, availability of public open spaces seems to be a strong predictor of MVPA. Future studies involving children should consider quantitative assessment of public recreational facilities in larger cities or urban sprawls in order to investigate the influence of the moveability on childhood PA in a broader sample.