Morton Katie L, Corder Kirsten, Suhrcke Marc, Harrison Flo, Jones Andy P, van Sluijs Esther M F, Atkin Andrew J
UKCRC Centre for Diet and Activity Research (CEDAR), MRC Epidemiology Unit, University of Cambridge School of Clinical Medicine, Box 285 Institute of Metabolic Science, Cambridge Biomedical Campus, Cambridge, CB20QQ, UK.
Centre for Health Economics, University of York, York, UK.
Int J Behav Nutr Phys Act. 2016 Apr 26;13:54. doi: 10.1186/s12966-016-0378-6.
There is increasing policy interest in ensuring that the school environment supports healthy behaviours. We examined the cross-sectional and longitudinal associations between schools' policies, programmes and facilities for physical activity (PA) and adolescents' objectively-measured activity intensity during the school day and lunchtime.
Accelerometer-derived PA (proportion of time spent in sedentary (SED), light PA (LPA) and moderate-to-vigorous PA (MVPA)) during school hours and lunchtime from 325 participants in the SPEEDY study were obtained from baseline measurements (primary school, age 9/10 years) and +4y follow-up (secondary school). School environment characteristics were assessed by teacher questionnaire. Multivariable multi-level linear regression analyses accounting for school and adjusted for sex, age, BMI and family socio-economic status assessed cross-sectional associations with lunchtime and school-day SED, LPA and MVPA; effect modification by sex was investigated. The association of changes in school environment with changes in outcomes was examined using multivariable cross-classified linear regression models.
There were significant differences between primary and secondary schools for 6/10 school environment characteristics investigated (including secondary schools reporting shorter breaks, more lunchtime PA opportunities, and higher number of sports facilities). Cross-sectional analyses showed that boys attending secondary schools with longer breaks spent significantly less time in SED and more time in MVPA during the school day. Longitudinally, an increase in break-time duration between primary and secondary school was associated with smaller reductions in MVPA during the school day. Moreover, participants who moved from a primary school that did not provide opportunities for PA at lunchtime to a secondary school that did provide such opportunities exhibited smaller increases in SED and smaller reductions in MVPA at lunchtime.
Schools should consider the potential negative impact of reducing break time duration on students' MVPA and SED during the school day. School-based interventions that combine longer breaks and more PA opportunities during lunchtime may be a fruitful direction for future research. Further research should also explore other factors in the school environment to explain the school-level clustering observed, and study sex differences in the way that the school environment influences activity intensity for adolescent populations.
确保学校环境支持健康行为的政策关注度日益提高。我们研究了学校体育活动（PA）的政策、项目和设施与青少年在校期间及午餐时间客观测量的活动强度之间的横断面和纵向关联。
从SPEEDY研究的325名参与者的基线测量（小学，9/10岁）和随访4年（中学）中获取在校时间和午餐时间通过加速度计得出的PA（久坐（SED）、轻度PA（LPA）和中度至剧烈PA（MVPA）所花费时间的比例）。学校环境特征通过教师问卷进行评估。多变量多层次线性回归分析考虑了学校因素，并对性别、年龄、BMI和家庭社会经济地位进行了调整，评估了与午餐时间和在校日SED、LPA和MVPA的横断面关联；研究了性别对效应的修饰作用。使用多变量交叉分类线性回归模型检验学校环境变化与结果变化之间的关联。
在所调查的10项学校环境特征中，小学和中学之间在6项特征上存在显著差异（包括中学报告课间休息时间较短、午餐时间PA机会更多以及体育设施数量更多）。横断面分析表明，在课间休息时间较长的中学上学的男孩在在校日久坐的时间显著减少，中度至剧烈PA的时间显著增加。纵向来看，小学和中学课间休息时间的增加与在校日MVPA减少幅度较小有关。此外，从午餐时间不提供PA机会的小学转到提供此类机会的中学的参与者，午餐时间SED的增加幅度较小，MVPA的减少幅度也较小。
学校应考虑缩短课间休息时间对学生在校日MVPA和SED的潜在负面影响。结合更长课间休息时间和午餐时间更多PA机会的校本干预措施可能是未来研究的一个富有成果的方向。进一步的研究还应探索学校环境中的其他因素，以解释观察到的学校层面的聚集现象，并研究学校环境影响青少年活动强度的方式中的性别差异。
