Teun Remmers

Investigating PA patterns in the transition from primary to secondary school | 167 Third, we found that total after school LPA and MVPA declined in the transition period, which supports conclusions from three studies (14, 18, 19). Also, in line with these three studies that suggested increased self-reported time spent on homework, leisure time TV and computer use in transition to secondary school (15-17), the present study showed that changes in after school PA were predominantly due to a decrease of PA performed at other locations (e.g. at friend's homes or at parks), and replaced by an increase in sedentary time at the residence. In addition, in line with two studies with a longer follow- up period (18, 19), but in contrast to one study that also investigated the one-year transition period (14) we found that average LPA and MVPA declined in weekends. Fourth, an additional aim of this present study was to investigate potential moderation of gender on the context-specific PA patterns in transition to secondary school. Although we generally found that MVPA in various contexts was higher in boys, we found only two significantly different transition coefficients. Namely, girls showed stronger increases of MVPA at shopping centres during weekends than boys in the transition period, while boys showed stronger declines of MVPA spent at school grounds than girls. The latter may be influenced by boys' considerably higher baseline MVPA at school grounds. Comparable studies investigating the specific one-year transition to secondary school found no gender differences (14-16), while other studies investigating the broader transition to adolescence (using longer follow-up periods) generally did find significant gender differences (4, 7, 19). This may mean that, although the present study indicated that there may be some gender differences at the residence and at other locations during weekends, the relatively short one-year follow-up period may be too short to detect significant gender differences in the development of PA patterns in other physical or behavioural contexts. Although we demonstrated considerable increases of transport-related LPA before-, during-, and after school in the transition phase, we found declines of active transport in weekends. Moreover, moderation analyses revealed that children with larger home- school differences (and thus more active transport during weekdays) tended to better maintain activity-related transport in weekends. We cautiously suggest that children with increased transport-related activity during weekdays (as a result of increased home- school difference) may have compensated this with declines of LPA at sports grounds after school and during weekends. Previous studies suggested that such compensation does not occur within children and within one day (13, 17, 23), contributing to the so- called "active synergy" hypothesis (22). Another study indicated that compensation within children of LPA and MVPA at the following day might occur when accounting for children's person-level activity (50), contributing to the so-called "activitystat" hypothesis (51, 52). However, investigating compensatory mechanisms was not the primary purpose of this paper, future research using more sophisticated within-person experimental designs and larger samples are needed to unravel compensation mechanisms in context-specific PA patterns. In the present study, sensitivity-analyses suggested that children with higher PA- levels at baseline were more likely to show a subsequent decline towards secondary school (data not shown).