RAND Corporation, Boston, Massachusetts.
Center for Economic and Social Research, University of Southern California, Los Angeles, California.
Am J Prev Med. 2018 May;54(5):671-678. doi: 10.1016/j.amepre.2018.01.030. Epub 2018 Mar 15.
Experimental and quasi-experimental evidence on the relationship between adolescents' physical activity and their physical activity environments is scarce. This study provides natural experimental evidence using within-person longitudinal variation in physical activity environments resulting from the compulsory re-assignment of military families to new installations, termed permanent changes of station.
Adolescents in Army families (N=749) reported usual weekly minutes of moderate and vigorous physical activity in 2013-2015. Objective measures of the physical activity environment, including the number of fitness and recreation facilities within 2 miles, were constructed for adolescents' neighborhoods using GIS methods. In 2017, individual-level fixed-effects models with and without a comparison group estimated the relationship between usual weekly minutes of physical activity and physical activity environments among permanent changes of station movers using within-person variation.
Increases in opportunities for physical activity were significantly and positively associated with increases in total (p<0.05) and vigorous physical activity (p<0.05) among adolescents who experienced permanent changes of station moves. The relationships were statistically significant for permanent changes of station movers living off-installation (p<0.05) and hence subject to greater variation in physical activity environments and those with more time to adjust to their new environments (p<0.05). Significant findings persisted when broader measures of physical activity environments were utilized.
The decline in physical activity and alarming obesity levels during adolescence suggest that this age may represent an important opportunity to address the obesity epidemic. This study provides evidence that increasing opportunities for physical activity may be an important pathway to improving their levels of physical activity and, consequently, obesity.
关于青少年的身体活动与身体活动环境之间的关系，实验和准实验证据很少。本研究利用由于军事家庭被强制重新分配到新设施（称为永久驻地变更）而导致身体活动环境的个体内纵向变化提供了自然实验证据。
军队家庭中的青少年（N=749）在 2013-2015 年报告了通常每周的中等强度和剧烈身体活动分钟数。使用 GIS 方法为青少年的社区构建了身体活动环境的客观指标，包括 2 英里内的健身和娱乐设施数量。在 2017 年，使用个体水平固定效应模型（有和没有对照组），根据个体内变化，估计了永久驻地变更移动者的通常每周身体活动分钟数与身体活动环境之间的关系。
在经历了永久驻地变更的青少年中，身体活动机会的增加与总身体活动（p<0.05）和剧烈身体活动（p<0.05）的增加呈显著正相关。对于住在驻地外（p<0.05）且身体活动环境变化更大的永久驻地变更移动者以及有更多时间适应新环境的移动者（p<0.05），这些关系具有统计学意义。当使用更广泛的身体活动环境指标时，显著的发现仍然存在。
青少年时期身体活动的减少和令人震惊的肥胖水平表明，这个年龄段可能是解决肥胖症流行的重要机会。本研究提供的证据表明，增加身体活动机会可能是提高他们身体活动水平、从而改善肥胖状况的重要途径。
