24h活动时间分布及替代与儿童身体质量指数的关系研究：基于成分分析模型
The Association of the Body Mass Index of Children with 24-Hour Activity Composition and Isotemporal Substitution:A Compositional Data Analysis
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摘要: 目的:使用成分分析方法综合探究上海市儿童24 h活动时间分布与身体质量指数(body mass index,BMI)之间的关系。方法:对上海市321名6~13岁学龄儿童(男生158名,女生163名)展开横断面调查,采用加速度计测量其24 h活动行为,采用标准测量仪器测量儿童身高、体质量;使用成分线性回归分析儿童24 h活动行为与身体质量指数z分数(body mass index z-score,zBMI)的关系,以及探讨24 h活动行为等时替代对zBMI的影响。结果:1)成分回归结果显示,控制性别和年龄后,中高强度身体活动(moderate-to-vigorous physical activity,MVPA)(β=-0.75,P<0.001)、低强度身体活动(light physical activity,LPA)(β=-0.13,P<0.05)的时间占比与儿童zBMI呈显著性负相关,久坐行为(β=0.61,P<0.001)和睡眠(β=0.53,P<0.01)的时间占比与儿童zBMI呈显著性正相关。2)在15 min等时替代模型中,用MVPA替代LPA、久坐行为和睡眠,以及用LPA替代久坐行为,会使zBMI显著性减少;用LPA、久坐行为和睡眠替代MVPA,以及用久坐行为替代LPA,则会使zBMI显著性增加。3)剂量-效应分析发现,MVPA与其他活动行为的相互替代对zBMI的影响具有不对称性,LPA与久坐行为的替代对zBMI的影响呈对称性;MVPA在替代久坐行为时对zBMI的降低效果最好;随着MVPA替代其他活动行为时间的增加,zBMI降低速度不断减慢,反之,zBMI增长速度不断变快。结论:家长和教师应着眼于儿童24 h活动整体,高度重视MVPA和LPA带来的积极效应,促进久坐行为向MVPA和LPA转换,以获得对儿童更好的健康效益。Abstract: Objective: To examine the relationships between 24-hour activity behaviors and body mass index(BMI) in Shanghai children by using compositional analyses. Methods: A cross sectional study was conducted on 321 primary school students(158 boys and 163 girls) aged 6-13 years in Shanghai. Time spent in 24-hour activity behaviors was determined by accelerometry,children's height and weight were measured by standard instruments. Compositional linear regression models were used to synthetically analyze the associations between the distribution of time spent 24-hour activity behaviors and zBMI, and the effect of compositional isotemporal substitution of 24-hour activity behaviors with zBMI was investigated as well. Results: 1) By controlling for gender and age, time spent in moderate-to-vigorous physical activity(MVPA)(β =-0.75, P<0.001) and light physical activity(LPA)(β=-0.13, P<0.05) was negatively associated with zBMI in children, while the time spent in sedentary behavior(β=0.61, P<0.001) and sleep(β =0.53, P<0.01) was positively correlated with zBMI; 2) The compositional isotemporal substitution models revealed reductions in zBMI when a 15-min reallocation from LPA, sedentary behavior and sleep to MVPA, and from sedentary behavior to LPA; however, a 15-min reallocation from MVPA to LPA, sedentary behavior and sleep, and from LPA to sedentary behavior was associated with higher zBMI; 3) According to the “dose-response” curves, firstly, the mutual substitution of MVPA and other activities has an asymmetric effect on zBMI and the substitution of LPA and sedentary behavior has a symmetrical effect on zBMI; secondly, the best reduction effect on zBMI is to replace sedentary behavior with MVPA; thirdly, with the increase time of MVPA isotemporal substitute other behaviors, the decrease in zBMI was slowed down, otherwise it increased rapidly. Conclusions:Parents and teachers should take 24-hour activities as a whole and attach great importance to the positive effects of MVPA and LPA,try to reallocate time from ST to MVPA and LPA of children so as to obtain better health benefits.
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