Department of Public and Occupational Health, Amsterdam Public Health research institute, VU University Medical Center, van der Boechorststraat 7, 1081BT, Amsterdam, the Netherlands.
MRC Epidemiology Unit, University of Cambridge, Cambridge, UK.
Int J Behav Nutr Phys Act. 2020 May 18;17(1):65. doi: 10.1186/s12966-020-00960-5.
To gain more understanding of the potential health effects of sedentary time, knowledge is required about the accumulation and longitudinal development of young people's sedentary time. This study examined tracking of young peoples' total and prolonged sedentary time as well as their day-to-day variation using the International Children's Accelerometry Database.
Longitudinal accelerometer data of 5991 children (aged 4-17y) was used from eight studies in five countries. Children were included if they provided valid (≥8 h/day) accelerometer data on ≥4 days, including ≥1 weekend day, at both baseline and follow-up (average follow-up: 2.7y; range 0.7-8.2). Tracking of total and prolonged (i.e. ≥10-min bouts) sedentary time was examined using multilevel modelling to adjust for clustering of observations, with baseline levels of sedentary time as predictor and follow-up levels as outcome. Standardized regression coefficients were interpreted as tracking coefficients (low: < 0.3; moderate: 0.3-0.6; high: > 0.6).
Average total sedentary time at study level ranged from 246 to 387 min/day at baseline and increased annually by 21.4 min/day (95% confidence interval [19.6-23.0]) on average. This increase consisted almost entirely of prolonged sedentary time (20.9 min/day [19.2-22.7]). Total (standardized regression coefficient (B) = 0.48 [0.45-0.50]) and prolonged sedentary time (B = 0.43 [0.41-0.45]) tracked moderately. Tracking of day-to-day variation in total (B = 0.04 [0.02-0.07]) and prolonged (B = 0.07 [0.04-0.09]) sedentary time was low.
Young people with high levels of sedentary time are likely to remain among the people with highest sedentary time as they grow older. Day-to-day variation in total and prolonged sedentary time, however, was rather variable over time.
为了更深入地了解久坐时间对健康的潜在影响，我们需要了解年轻人久坐时间的积累和纵向发展情况。本研究利用国际儿童加速计数据库，探讨了年轻人久坐总时间和长时间久坐以及日常变化的追踪情况。
本研究共纳入了来自五个国家八个研究的 5991 名儿童（年龄 4-17 岁）的纵向加速度计数据。如果儿童在基线和随访时提供了有效（≥8 小时/天）的加速度计数据（≥4 天，包括至少 1 个周末），则将其纳入研究。平均随访时间为 2.7 年（范围为 0.7-8.2 年）。使用多层次模型来调整观察的聚类，以久坐时间的基线水平作为预测值，以随访水平作为结果值，从而评估久坐总时间和长时间（即≥10 分钟的时间段）久坐时间的追踪情况。标准回归系数被解释为追踪系数（低：<0.3；中：0.3-0.6；高：>0.6）。
在研究水平上，平均总久坐时间在基线时为 246-387 分钟/天，平均每年增加 21.4 分钟/天（95%置信区间[19.6-23.0]）。这种增加几乎完全由长时间久坐时间（20.9 分钟/天[19.2-22.7]）构成。总（标准化回归系数（B）=0.48[0.45-0.50]）和长时间久坐时间（B=0.43[0.41-0.45]）的追踪效果中等。总（B=0.04[0.02-0.07]）和长时间（B=0.07[0.04-0.09]）久坐时间的日间变化的追踪效果较低。
久坐时间较高的年轻人随着年龄的增长，他们很可能仍然是久坐时间最高的人群之一。然而，总久坐时间和长时间久坐时间的日间变化在较长时间内变化较为复杂。
