Teun Remmers

208 | Summary Chapter 8 describes a study on relationships between attributes of the objective physical environment and children's afterschool PA. In this study, we have collected and analyzed accelerometer and GPS data from the PHASE-kids study in 's-Hertogenbosch, the Netherlands. This project was initiated to analyze measurements of PA in the transition from primary to secondary school and its relationship with factors in the physical environment. Based on information from both Global Positioning Systems (GPS) and Geospatial Information Systems (GIS) this study was able to study specific contexts of the afterschool time-segment such as leisure time, bicycling, walking, and organized sport participation. As children are exposed to multiple environments in the afterschool time period, this study focused on the influence of the combined home-, school-, and daily transport environment between their home and school. We found that afterschool leisure time PA was associated with environments containing more greenspace (i.e. lawns and shrubs), buildings and pedestrian paths, and with environments containing smaller home- school distances. In addition, cycling was associated with larger home-school distances and environments with more pedestrian areas and sports terrains, while fewer minutes of cycling was associated with more buildings, lawns, and pedestrian paths. Walking was associated with environments containing more agriculture, shrubs, main roads and pedestrian paths, and smaller home-school distances. Collectively, this study revealed relevant environmental determinants of afterschool leisure time and transport-related PA by combining accelerometer, GPS and GIS data. Chapter 9 describes a longitudinal study on the development of PA patterns in the transition between primary and secondary school. Here we used data from the PHASE- kids study and selected children with accelerometer and GPS measurements collected both in the last year of primary school and first year of secondary school. Based on information from GPS and GIS data, this study was able to specify multiple contexts: participant's residence, school, sports grounds, and other places. In addition, analyses were separated for the time-segments before school, during school, after school and weekend days. We found that light PA and moderate-to-vigorous PA declined, especially after school and during weekends. The major components that decreased from primary to secondary school were 1) increased sedentary time at the residence, 2) decreased light PA at sports grounds, and 3) decreased light PA and moderate-to-vigorous PA at other locations. In addition, transport-related activity significantly increased during weekdays, and stronger increases were found for children with greater increases in distance from the residence to their school. This study provided in-depth insights of where, and at which time periods changes in children's PA patterns occur.