Janz Kathleen F, Boros Piroska, Letuchy Elena M, Kwon Soyang, Burns Trudy L, Levy Steven M
1Department of Health and Human Physiology, University of Iowa, Iowa City, IA; 2Department of Epidemiology, University of Iowa, Iowa City, IA; 3Stanley Manne Children's Research Institute, Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, IL; 4Department of Pediatrics, University of Iowa, Iowa City, IA; and 5Department of Preventive and Community Dentistry, Iowa City, IA.
Med Sci Sports Exerc. 2017 Oct;49(10):2071-2077. doi: 10.1249/MSS.0000000000001336. Epub 2017 Jun 2.
To examine the associations among physical activity (PA), sedentary time (SED), and TV viewing (TV) with fat mass (FAT) and visceral adipose tissue mass (VAT) from childhood through adolescence (5-19 yr).
Participants in the Iowa Bone Development Study (n = 230 males and 233 females) were examined at ages 5, 8, 11, 13, 15, 17, and 19 yr. Accelerometers measured moderate- or vigorous-intensity PA (MVPA; min·d), light-intensity PA (LPA; min·d), and SED (h·d). Parent-proxy report (5 and 8 yr) and child-report (11, 13, 15, 17, and 19 yr) measured TV (h·d). X-ray absorptiometry scans measured FAT (kg) and VAT (g). Sex-specific growth models were used to create FAT and VAT growth curves for individual participants (level 1), and to test the effect of MVPA, LPA, SED, and TV (level 2) after adjusting for weight, height, linear age, nonlinear age, and maturity.
Growth models indicated that low levels of MVPA were associated with high levels of FAT and VAT for males and high levels of FAT for females. TV viewing was positively associated with FAT and VAT for males and females. LPA was positively associated with FAT in males. Sedentary time was not associated with FAT or VAT for males or females (P > 0.05).
This study supports current PA guidelines focusing on MVPA rather than SED. The contribution of high TV, but not high SED, to high levels of adiposity suggests that TV's contribution to obesity is not just a function of low energy expenditure.
研究从儿童期到青春期（5 - 19岁）身体活动（PA）、久坐时间（SED）和看电视时间（TV）与脂肪量（FAT）和内脏脂肪组织量（VAT）之间的关联。
爱荷华骨骼发育研究的参与者（230名男性和233名女性）在5、8、11、13、15、17和19岁时接受检查。加速度计测量中等强度或剧烈强度的身体活动（MVPA；分钟·天）、轻度强度的身体活动（LPA；分钟·天）和久坐时间（小时·天）。家长代理报告（5岁和8岁）以及儿童报告（11、13、15、17和19岁）测量看电视时间（小时·天）。双能X线吸收法扫描测量脂肪量（千克）和内脏脂肪组织量（克）。使用性别特异性生长模型为个体参与者创建脂肪量和内脏脂肪组织量的生长曲线（第1层），并在调整体重、身高、线性年龄、非线性年龄和成熟度后测试中等强度或剧烈强度的身体活动、轻度强度的身体活动、久坐时间和看电视时间的影响（第2层）。
生长模型表明，低水平的中等强度或剧烈强度的身体活动与男性的高脂肪量和内脏脂肪组织量以及女性的高脂肪量相关。看电视时间与男性和女性的脂肪量和内脏脂肪组织量呈正相关。轻度强度的身体活动与男性的脂肪量呈正相关。久坐时间与男性或女性的脂肪量或内脏脂肪组织量无关（P>0.05）。
本研究支持当前侧重于中等强度或剧烈强度的身体活动而非久坐时间的身体活动指南。长时间看电视而非久坐对高水平肥胖的影响表明，看电视对肥胖的影响不仅仅是低能量消耗的作用。
