Social and Economic Well Being, RAND Corporation, Santa Monica, CA, United States of America.
Statistics, RAND Corporation, Santa Monica, CA, United States of America.
PLoS One. 2019 Nov 6;14(11):e0223737. doi: 10.1371/journal.pone.0223737. eCollection 2019.
Light physical activity (LPA) and patterns of sedentary behavior influence cardio-metabolic health independently of moderate-to-vigorous physical activity. Understanding the trajectory and determinants of these activity levels over time may provide insights relevant to public health practice.
We measured a cohort of young women recruited in middle school (age 14) using accelerometry for 1 week and remeasured them in high school (age 17) and again at age 23 (n = 385). We assessed changes in LPA and patterns of sedentary behavior by hours in a day. We examined the association of social and contextual factors, including employment status, screen time, and neighborhood context with LPA and sedentary behavior patterns.
The amount of LPA decreased over time, while the length of LPA bouts tended to increase. Sedentary bout durations increased over time and sedentary breaks decreased. Sedentary time and bout length were correlated with internet use, rather than with TV or videogaming. Employment was associated with less sedentary time; being a student was associated with longer sedentary time and bouts.
Because LPA and sedentary breaks can be protective for cardio-metabolic health, and the duration of sedentary bouts increase as women age from adolescence to young adulthood, worksites and college campuses should remind employees and students to take frequent activity breaks when they use computers and the internet for long stretches.
轻度身体活动（LPA）和久坐行为模式独立于中等至剧烈身体活动影响心血管代谢健康。了解这些活动水平随时间的变化轨迹和决定因素可能为公共卫生实践提供相关见解。
我们使用加速度计对一群在中学（14 岁）招募的年轻女性进行了 1 周的测量，并在高中（17 岁）和 23 岁（n=385）再次对她们进行了测量。我们通过每天的小时数评估 LPA 和久坐行为模式的变化。我们研究了社会和环境因素，包括就业状况、屏幕时间和邻里环境与 LPA 和久坐行为模式的关联。
LPA 的量随时间减少，而 LPA 回合的长度往往增加。久坐回合的持续时间随时间增加，而久坐休息时间减少。久坐时间和回合长度与互联网使用相关，而与电视或电子游戏无关。就业与较少的久坐时间有关；学生身份与较长的久坐时间和回合有关。
由于 LPA 和久坐休息时间对心血管代谢健康有保护作用，并且随着女性从青少年到成年早期的年龄增长，久坐回合的持续时间增加，因此工作场所和大学校园应提醒员工和学生在长时间使用计算机和互联网时经常进行活动休息。
