Teun Remmers

166 | Chapter 9 Discussion This was the first study to use combined accelerometer, GPS and GIS data to investigate the longitudinal associations between PA patterns and its context in the transitional phase from primary to secondary school. Building upon the evidence from earlier studies showing a decline of PA in the transition from childhood to adolescence (4-7, 17-19), this study adds in-depth insight of where and during which time-segment during the day these declines occur. Several results were in line with findings of previous studies. First, in line with self- reported increases in overall transport-related PA in transition to secondary school (11, 13, 15, 16), we also found significant increases in active transport before-, during-, and after school in the transition phase from primary to secondary school. Also, in line with three studies (13, 22, 23), we found that this increase was a result of the increased distance between home and school. Namely, transport-related activity during weekdays increased significantly more in children with larger home-school differences. Among a relatively younger but otherwise comparable Dutch sample Dessing et al. (2014) found that when the distance between home and primary school exceeded 900 meters, probability of using passive transport was >50% (average distance from home to school in this study was 364 meters, compared to the present study average of 620 meters) (23). These findings are not in line with the present study, as we showed that when transitioning to secondary school, children that were facing bigger distances to their school did not spend significantly more time in passive transport (average distance from home to secondary school was 3127 meters). This may be due to the increased responsibility parents provide these children at older ages. Future studies are encouraged to replicate these designs in other geographical and cultural contexts. Secondly, we found that total LPA and MVPA during school time was relatively stable over time, which supports conclusions of a 4-year follow-up study of Brooke et al. (2014) (19), but contrasts results from the 3-year follow-up study of Harding et al. (2015) (18) who reported parallel decreases of LPA during school, after school, and in weekends in the transition phase between primary and secondary school. Also, the number of minutes spent in MVPA during school hours was comparable with two previous studies (16, 46). More specifically, we found that after the transition less sedentary and LPA time was spent at the school-parcel. This was replaced by sedentary time at home and other locations. Emerging evidence links daily PA and active breaks to academic performance (47-49), and this may provide schools with opportunities for increasing PA (and thus also improving academic performance) during school hours, for example by high quality physical education lessons. Moreover, parents and health promotors are also encouraged to provide infrastructure to prevent prolonged sedentary time at home, for example by active videogames or social activities.