Teun Remmers

106 | Chapter 7 environment (and their specific features such as lightning and trees) and ASPA in children (22, 24). However in the audits of the studies above, no information was recorded about the quality of these PA-facilities (e.g. attractiveness, maintenance status or age- appropriateness). This may be important, as other factors than actual distance to public open spaces may determine the use of public open spaces or playgrounds (24, 29). An advantage of investigating ASPA is that when using exact school bell-times, relationships between ASPA and attributes of the school-environment can be investigated with an equal starting-point; both regarding time-opportunities and geographical location for all children attending the same school. To even further improve our understanding of this association, the ASPA time-period may be separated into even more precise time- segments after school bell-times. For example, by theory, children are all optimally exposed to the school-environment directly after school ends (i.e. bell times) but to a lesser extent later in the afternoon. Greater distances of a child’s residence to the school- environment may attenuate relationships between playability and ASPA, because children living further away may be more likely to engage in ASPA at places outside the school- environment under study. Consequently, the present study used an ecological approach to investigate the association between environmental playability and objectively measured ASPA of 8-11 year-old children, using audits of school-environments. In addition, we aimed to demonstrate that with increasing specificity in time and distance, relationships between school-environments and ASPA can be revealed and made plausible. Methods This investigation was embedded in a prospective study in the Southeast part of the Netherlands, focusing on environmental attributes and PA in Dutch primary school children. The design and protocol are described in detail elsewhere (30). After obtaining parental informed consent, 815 sixth and seventh grade primary-school pupils from 21 schools participated in PA measurements and questionnaires for both one of the parents and child. Data collection took place between the 26 th of September and the 1 st of December 2012 and analyses were performed in 2015. The Medical Ethics Committee of the Maastricht University Medical Center approved this study (reference number METC 12-4-077). Measurements After-School Physical Activity ASPA was measured using ActiGraph GT3X+ accelerometers (30Hz) for five consecutive days (ActiGraph, Pensacola, FL), defining non-wear periods according to 60 minutes of consecutive zero’s according to Troiano’s criteria (31). Activity intensity classification was based on Evenson’s cutpoints (32). Participants were instructed to only remove the