BACKGROUND Increasing emphasis has been placed on improving physical activity levels through multilevel interventions. This study aims to examine moderating effects of neighborhood safety (crime and traffic) and social support (from parent and sibling/peer) for physical activity in the relationship between the built environment and moderate-to-vigorous physical activity (MVPA) outside school hours among adolescents in Melbourne. METHODS Data were from the NEighbourhood Activity in Youth study conducted among adolescents in Melbourne, Australia (n = 358, 15.3 (SD = 1.5) years). MVPA outside school hours was assessed by accelerometer. Built environment features within 1 km and 2 km residential buffers including recreation facilities, park area, and walkability and its components were assessed using Geographic Information Systems. Neighborhood safety, social support for physical activity and sociodemographic information were self-reported by adolescents. Multilevel linear regression models were used to estimate associations. RESULTS Support for physical activity from sibling/peer positively moderated the relationship between recreation facilities (1 km), residential density (2 km) and MVPA. Recreation facility (count within 2 km), walkability (1 km and 2 km) and residential density (1 km) had significant positive associations with MVPA outside school hours. CONCLUSION The built environment appeared to have stronger facilitating effects on MVPA among adolescents who had favourable support for physical activity from their sibling or peer. Multilevel interventions that target the built environment and social factors are needed to promote MVPA outside school hours among adolescents.

中文翻译：

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青少年的建筑环境和体育活动：社区安全和社会支持的调节作用。

背景技术越来越多的重点放在通过多层次干预来改善身体活动水平上。这项研究的目的是研究在课余时间建筑环境与中度至剧烈体育活动（MVPA）之间的关系中，邻里安全（犯罪和交通）和社会支持（父母和兄弟姐妹/同伴）对体育活动的调节作用在墨尔本的青少年中。方法数据来自澳大利亚墨尔本（n = 358，15.3（SD = 1.5）岁）青少年中进行的“青年邻里活动”研究。在课余时间通过加速度计评估MVPA。使用地理信息系统评估了1 km和2 km住宅缓冲区内的建筑环境特征，包括娱乐设施，公园区域和步行性及其组成部分。青少年自我报告了邻里安全，体育活动的社会支持和社会人口统计学信息。多级线性回归模型用于估计关联。结果兄弟姐妹/同伴对体育锻炼的支持积极地缓解了娱乐设施（1公里），住宅密度（2公里）和MVPA之间的关系。娱乐设施（计数在2公里以内），步行能力（分别在1公里和2公里之内）和居民密度（在1公里之内）与MVPA在课余时间之间具有显着的正相关关系。结论在兄弟姐妹或同伴对体育锻炼有良好支持的青少年中，建筑环境似乎对MVPA具有更强的促进作用。