Critical hours and important environments : relationships between afterschool physical activity and the physical environment using GPS, GIS and accelerometers in 10-12-year-old children - Remmers, Teun, Docent; Thijs, Carel; Ettema, Dick; Vries,de, S.I. (Sanne), Lector; Slingerland, Menno, Docent; Kremers, Stef (International Journal of Environment Research and Public Health, 2019)