Huang Wendy Yajun, Wong Stephen Heung-Sang, He Gang, Salmon J O
1Department of Physical Education, Hong Kong Baptist University, Hong Kong, CHINA; 2Department of Sports Science and Physical Education, The Chinese University of Hong Kong, Hong Kong, CHINA; 3School of Kinesiology and Health, Capital University of Physical Education and Sports, Beijing, CHINA; and 4Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, AUSTRALIA.
Med Sci Sports Exerc. 2016 Nov;48(11):2135-2141. doi: 10.1249/MSS.0000000000001002.
This study examined the prospective associations of reallocating time spent in different types of sedentary behavior, physical activity, and sleep with body mass index (BMI) in children using isotemporal substitution analysis.
Chinese children in grades 1-3 were recruited to a cohort study in 2009 and were followed up over a 2-yr period. Reports were gathered from the parents on children's sedentary behavior, sleep duration, and sociodemographic variables. The reported sedentary behavior types were then grouped into three categories: screen time (e.g., watching TV), academic-related activities (e.g., doing homework), and other sedentary behaviors (e.g., sitting and talking). Moderate-to-vigorous physical activity (MVPA) and light-intensity physical activity were assessed by ActiGraph accelerometry (ActiGraph, Pensacola, FL). Isotemporal substitution models were performed to examine the effects of time allocation on BMI.
A total of 672 children (359 boys, mean age at recruitment = 7.6 yr) who had provided valid accelerometer data for at least one assessment time point were included in the analysis. Controlling for covariates and total behavior time, isotemporal substitution models indicated that the displacement of 30 min·d of other sedentary behaviors with equal amounts of screen time (B = 0.12; 95% confidence interval, 0.04-0.20) or academic-related activities (B = 0.13; 95% confidence interval, 0.04-0.21) was associated with higher BMI. Reallocating 30 min·d of MVPA with each of the sedentary behavior variables resulted in increased BMI.
The substitution of screen time or academic-related activities with other sedentary behaviors or MVPA was associated with lower BMI in Chinese children.
本研究采用等时替代分析方法，探讨重新分配儿童在不同类型久坐行为、体育活动和睡眠上所花费的时间与体重指数（BMI）之间的前瞻性关联。
2009年，1至3年级的中国儿童被纳入一项队列研究，并随访2年。收集家长关于孩子久坐行为、睡眠时间和社会人口统计学变量的报告。报告的久坐行为类型随后分为三类：屏幕时间（如看电视）、学业相关活动（如做作业）和其他久坐行为（如坐着交谈）。通过ActiGraph加速度计（ActiGraph，彭萨科拉，佛罗里达州）评估中度至剧烈体育活动（MVPA）和轻度体育活动。采用等时替代模型来研究时间分配对BMI的影响。
共有672名儿童（359名男孩，招募时平均年龄 = 7.6岁）至少在一个评估时间点提供了有效的加速度计数据，并纳入分析。在控制协变量和总行为时间后，等时替代模型表明，用等量的屏幕时间（B = 0.12；95%置信区间，0.04 - 0.20）或学业相关活动（B = 0.13；95%置信区间，0.04 - 0.21）替代每天30分钟的其他久坐行为与较高的BMI相关。将每天30分钟的MVPA与每种久坐行为变量进行重新分配会导致BMI升高。
在中国儿童中，用其他久坐行为或MVPA替代屏幕时间或学业相关活动与较低的BMI相关。
