Mann K D, Howe L D, Basterfield L, Parkinson K N, Pearce M S, Reilly J K, Adamson A J, Reilly J J, Janssen X
Newcastle University, Institute of Health and Society, Newcastle upon Tyne, UK.
University of Bristol, School of Social and Community Medicine, MRC integrative Epidemiology Unit at Bristol University, Bristol, UK.
Int J Obes (Lond). 2017 Jul;41(7):1042-1047. doi: 10.1038/ijo.2017.69. Epub 2017 Mar 15.
Sedentary time (ST) has been reported to have a range of negative health effects in adults, however, the evidence for such effects among children and adolescents is sparse. The primary aim of the study was to examine associations between changes in sedentary behavior (time and fragmentation) and changes in adiposity across childhood and adolescence.
Participants were recruited as part of the Gateshead Millennium Study. Measures were taken at age 7 (n=502), 9 (n=506), 12 (n=420) and 15 years (n=306). Participants wore an ActiGraph GT1M and accelerometer epochs were 'sedentary' when recorded counts were ⩽25 counts per 15 s. ST was calculated and fragmentation (SF) was assessed by calculating the number of sedentary bouts per sedentary hour. Associations of changes in ST and SF with changes in adiposity (body mass index (BMI), and fat mass index (FMI)) were examined using bivariate linear spline models.
Increasing ST by 1% per year was associated with an increase in BMI of 0.08 kg m per year (95% CI: 0.06-0.10; P<0.001) and FMI of 0.15 kg m per year (0.11-0.19; P<0.001). Change in SF was associated with BMI and FMI (P<0.001). An increase of 1 bout per sedentary hour per year (that is, sedentary time becoming more fragmented) was associated with an increase in BMI of 0.07 kg m per year (0.06-0.09; P<0.001) and an increase in FMI of 0.14 kg m per year (0.10-0.18; P<0.001) over the 8 years period. However, an increase in SF between 9-12 years was associated with a 0.09 kg m per year decrease in BMI (-0.18-0.00; P=0.046) and 0.11 kg m per year decrease in FMI (-0.22-0.00; P=0.049).
Increased ST and increased SF from 7-15 years were associated with increased adiposity. This is the first study to show age-specific associations between change in objectively measured sedentary behavior and adiposity after adjustment of moderate-to-vigorous-intensity physical activity in children and adolescents. The study suggests that, targeting sedentary behavior for obesity prevention may be most effective during periods in which we see large increases in ST.
据报道，久坐时间（ST）对成年人有一系列负面健康影响，然而，关于儿童和青少年此类影响的证据却很少。本研究的主要目的是探讨童年和青少年时期久坐行为（时间和碎片化程度）的变化与肥胖变化之间的关联。
参与者作为盖茨黑德千禧年研究的一部分被招募。在7岁（n = 502）、9岁（n = 506）、12岁（n = 420）和15岁（n = 306）时进行测量。参与者佩戴ActiGraph GT1M，当记录的每15秒计数⩽25次时，加速度计的时间段被定义为“久坐”。计算久坐时间，并通过计算每久坐小时的久坐时段数来评估碎片化程度（SF）。使用双变量线性样条模型研究久坐时间和碎片化程度的变化与肥胖变化（体重指数（BMI）和脂肪量指数（FMI））之间的关联。
每年久坐时间增加1%与每年BMI增加0.08 kg/m²（95%置信区间：0.06 - 0.10；P < 0.001）以及每年FMI增加0.15 kg/m²（0.11 - 0. ... 19；P < 0.001）相关。碎片化程度的变化与BMI和FMI相关（P < 0.001）。在8年期间，每年每久坐小时久坐时段增加1次（即久坐时间变得更加碎片化）与每年BMI增加0.07 kg/m²（0.06 - 0.09；P < 0.001）以及每年FMI增加0.14 kg/m²（0.10 - 0.18；P < 0.001）相关。然而，9至12岁之间碎片化程度的增加与每年BMI下降0.09 kg/m²（-0.18 - 0.00；P = 0.046）以及每年FMI下降0.11 kg/m²（-0.22 - 0.00；P = 0.049）相关。
7至15岁久坐时间增加和碎片化程度增加与肥胖增加相关。这是第一项在调整了儿童和青少年中度至剧烈强度身体活动后，显示客观测量的久坐行为变化与肥胖之间存在年龄特异性关联的研究。该研究表明，针对久坐行为进行肥胖预防可能在久坐时间大幅增加的时期最为有效。
