Teun Remmers

Playability of school environments and afterschool PA | 107 accelerometer in water-related activities, so we explicitly instructed them to keep wearing them during sports-activities. We excluded measurements containing less than 250 minutes per day of registration time, for at least two weekdays. Although studies investigating whole-day PA patterns usually apply more stringent criteria for these registration times (33), we were only interested in a smaller part of the daily PA pattern and therefore required less registration time. Weekend days and Wednesdays (because of a shortened school-schedule) were excluded. Accelerometry was aggregated to hourly averages, for each day of measurement. Using weartime-filters, ASPA was filtered from total PA registration time, based on exact school’s bell times. ASPA was then separated in four two-hour time periods: 1) directly after-school–16:00, 2) 16:00-18:00, 3) 18:00-20:00, and 4) 20:00–22:00. All schools ended between 14:45 and 15:30. To ensure that these time-periods represented hourly patterns, and are thus not influenced by spurious PA- spikes in children with limited period-specific weartimes, we only included accelerometer data that consisted of at least 50% of the period-specific registration time (i.e. at least one hour in a two-hour registration period) (26, 27, 34). For the first time period, we tailored the percentage of period-specific weartime based on individual school bell-times. Based on data from the Royal Dutch Meteorological Institute (KNMI), we also identified meteorological circumstances (i.e. average temperature, average duration of rainfall, and average duration of sunshine per day) during measurement-days. Playability Playability of the school-environments was assessed by two trained researchers using the SPACE observation instrument (35, 36), within an 800 meters radius from each school, while acknowledging natural barriers such as highways or canals. This 54-item instrument audits PA friendliness of neighborhoods and assesses characteristics such as residential density, playground characteristics, and traffic intensity, based on the Neighborhood Environment Walkability Scale but modified to reflect the Dutch environmental context (37, 38). Inter-rater agreement between the two researchers who audited school- environments was acceptable (Kappa = 0.73). Playability was operationalized by first extracting items representing characteristics of playgrounds (excluding schoolyards) within the 800 meters crow-fly surface areas. Extracted were the playground’s size in squared meters, accessibility (safely accessible versus not-safely accessible), opening hours (unlimited versus limited), maintenance-status (poor versus good), number of facilities (e.g. climbing-facilities and soccer goals), and age-appropriateness of these facilities for 8-11 year-old children (none, partly, and fully age-appropriate). Each individual playground-characteristic was summed and standardized based on equal weights, to reflect one standardized score for each individual playground. Subsequently, these scores were aggregated to a playability index-score for each school-environment. Distance from children’s residence to their school Since in the Netherlands a limited number of primary schools generally cover a small residential area, parent’s decisions regarding the school of their children is often based on the (close) distance from their residence (39, 40). Because of this vicinity to their school,