Abstract: Objective To explore the health benefits of high intensity physical activity (MVPA), light intensity physical activity (LPA), and sedentary behavior (SB) substitution for each other in equal time on body mass index (BMI), waist height ratio (WHtR) and body fat percentage (BFP). Methods From November to December 2021, 193 students in a middle school in Tianjin were selected as study subjects. Height, weight, waist circumference, BFP of the participants were measured, BMI and WHtR were calculated. Students were asked to wear Actigraph GT3X acceleration sensor for 7 days, MVPA, LPA and SB were recorded. Multiple linear regression was used to analyze the effects of isochronous substitution of different types of activities on BMI, WHtR and BFP. Results The prevalence of overweight, obesity and abdominal obesity in children was 14.0% (27/193), 17.1% (33/193), and 25.4% (49/193), respectively. Overweight obese children and abdominally obese children showed lower levels of MVPA and LPA, and MVPA and LPA were negatively correlated with BMI, WHtR and BFP (r=-0.416, -0.352, -0.430, -0.358, -0.337, -0.324, P<0.01), while SB was positively correlated with BMI, WHtR and BFP (r=0.456, 0.360, 0.414, P<0.01). Replacing LPA with 15min/d MVPA significantly reduced BMI, WHtR and BFP (P<0.01). BMI, WHtR and BFP were further decreased when SB was replaced by MVPA at 15min/d (P<0.01). Using 15min/d of LPA to replace the equivalent time ofSB also resulted in decrease in BMI, WHtR, and BFP (P< 0.01). Conclusions MVPA isochronous replacement of LPA and SB time can produce good health benefits on BMI, WHtR and BFP, and the same amount of LPA isochronous replacement of SB time can also produce good health benefits.Allocating more SB time to MVPA and LPA can effectively reduce the body fat level of children. In particular, increasing the MVPA time has a better effect on the prevention and treatment of obesity risk in children.

Key words: children, obesity, physical activity, sedentary behavior

摘要： 目的 探讨等量时间中高强度身体活动(MVPA)、低强度身体活动(LPA)、久坐行为(SB)相互替代对于体质量指数(BMI)、腰高比(WHtR)、体脂率(BFP)产生的健康效益。方法 于2021年11—12月选取天津市一所初中193名学生为研究对象,受试者测定身高、体重、腰围、BFP,并计算BMI和WHtR,佩戴Actigraph GT3X加速度传感器7d,记录MVPA、LPA和SB,采用多元线性回归的方法分析不同类型活动的等时替换对BMI、WHtR和BFP产生的效应。结果 儿童超重、肥胖率分别为14.0%(27人)、17.1%(33人),腹型肥胖率25.4%(49人)。超重肥胖儿童和腹型肥胖儿童MVPA和LPA表现出更低的水平,MVPA、LPA与BMI、WHtR、BFP均呈负相关(r=-0.416、-0.352、-0.430、-0.358、-0.337、-0.324,P＜0.01),SB与BMI、WHtR、BFP均呈正相关(r=0.456、0.360、0.414,P＜0.01)。使用15min/d的MVPA替换同等时间的LPA,BMI、WHtR、BFP均明显降低(P＜0.01);而用15min/d的MVPA替代同等时间的SB,BMI、WHtR、BFP均进一步降低(P＜0.01);使用15min/d的LPA替代同等时间的SB,也会使BMI、WHtR、BFP降低(P＜0.01)。结论 MVPA等时替代LPA和SB时间均能对BMI、WHtR、BFP产生良好的健康效益,同样用等量LPA等时替代SB时间也能产生较好的健康效益,将更多的SB时间分配给MVPA和LPA能有效降低儿童体重和体脂水平,尤其增加MVPA时间对防治儿童肥胖风险效果更佳。

关键词: 儿童, 肥胖, 身体活动, 久坐