Increasing knowledge concerning correlates of adolescent physical activity and sedentary time is important for health promotion efforts in schools. It is logical to examine cross-sectional and longitudinal associations between different factors and physical activity, as this will provide insights into potential strategies that may be effective in the longer-term if implemented. Moreover, this information has the potential to identify which sub-groups of the population may benefit from physical activity promotion strategies during school break time. Consistent with studies that have objectively 
and subjectively 
measured adolescent physical activity in this context, males engaged in more physical activity and less sedentary time than females. There is a need to establish why adolescent males are more active than females to inform future intervention efforts, and future research should be adequately powered in order to examine correlates of their break time physical activity separately. Interestingly, while both males' and females' engagement in%MVPA was low during break time, approximately 40% of their school break time was spent engaged in%LPA. This raises questions whether interventions during break time should focus on increasing%MVPA or increasing overall physical activity participation (i.e., LPA and MVPA), particularly as bringing sports equipment to school was associated with higher %LPA during school break time two years later.
Adolescents' have previously suggested that the provision of sports equipment and organised activities during lunchtime may benefit their physical activity levels 
. Indeed, the provision of organised activities to adolescents during school break time has been found to be positively associated with MVPA 
. The present study lends some support to these findings as engaging in sport/physical activity during break time was longitudinally associated with higher%LPA and%MVPA engagement. It is possible that adolescents who choose to engage in sport/physical activity during break time retain this pattern of activity over time. However, this finding also suggests that identifying strategies to enable and sustain participation in these behaviours warrants further attention, particularly as decreases in adolescent break time physical activity have been observed over time 
. Such strategies may be particularly important for adolescent girls, given their lower physical activity levels in school break time.
Previous research has found that social support from parents, peers and school are correlates of daily 
and break time 
physical activity. No cross-sectional or longitudinal associations were found for family and peer social support in this study. The first finding may be explained by their increasing independence from their parents 
. During this transition, friends become increasingly important as a source of social support and help to establish social norms concerning physical activity behaviours 
. Previous research has found that the number of active friends adolescents have was associated with daily physical activity 
and informal game play at school 
, whilst not having any friends to be active with was a barrier to lunchtime physical activity 
. The present study did not determine the number of friends adolescents had to be active with during break time (a limitation of this study), which may explain, in part, the lack of associations obtained. In addition, the measures used to examine family and peer support may also have impacted on the findings as these were related to support for physical activity overall rather focusing specifically on break time, which is one opportunity for regular engagement in physical activity. Further research is needed to establish the extent to which social support from peers, parents and the school are associated with break time physical activity and sedentary time, and whether strategies for developing social support for activity may be effective for increasing physically active behaviours during school break time.
This present study found a positive cross-sectional association between%MVPA and bringing in sports equipment. Moreover, being allowed to bring in sport equipment to school was also positively associated with%LPA during break time two years later. Adolescents have identified that providing access to school-owned equipment would be one approach that would facilitate their activity choices 
, yet this study suggests that encouraging students to bring in their own sports equipment from home may facilitate physical activity engagement. It is possible that adolescents who can bring in their own sports equipment are more motivated and interested in being physically active 
. Overall, these findings suggest that permitting adolescents to bring in their own equipment may reduce perceptions of there being nothing to do during school break time 
and may be simple but effective strategy for increasing physical activity engagement and decreasing sedentary time during break time. However, further research is needed to examine the effectiveness of school policies relating to bringing in equipment on adolescents' physical activity levels as no other studies have examined this association to date 
The strengths of this study include objective measurement of physical activity and sedentary time during break times, and the longitudinal data collection. There are, however, several limitations that warrant attention. First, no data were collected concerning the actual behaviours that the adolescents engaged in during break time. Directly observing behaviour, for example, would provide further information concerning how adolescent's use break time to engage in physical activity and sedentary behaviours. In particular, understanding which activities contribute to%LPA engagement during break time is likely to inform intervention strategies, particularly as it accounts for ~40% of the school day. Second, it is not known whether the adolescents had access to structured lunchtime activities, both sports and academic related, and if so how often they were attended and how long for. It is possible that such lunchtime activities may have impacted on the results obtained. Third, few school level variables were available for analysis in the present study. Correlates such as facility availability, playground size, number of children attending the school, and break time policies, which have been associated with physical activity levels in preschool and elementary school children 
warrant further attention in adolescents. Fourth, the small sample size for the analyses may affect the generalizability of the results and the ability to determine significant associations, particularly as the magnitude of change in physical activity and sedentary time between T2 and T3 was small.