Sera Francesco, Griffiths Lucy J, Dezateux Carol, Geraci Marco, Cortina-Borja Mario
Department of Social and Environmental Health Research, London School of Hygiene and Tropical Medicine, London, United Kingdom.
Population, Policy and Practice Programme, UCL Great Ormond Street Institute of Child Health, London, United Kingdom.
PLoS One. 2017 Nov 8;12(11):e0187677. doi: 10.1371/journal.pone.0187677. eCollection 2017.
Temporal characterisation of physical activity in children is required for effective strategies to increase physical activity (PA). Evidence regarding determinants of physical activity in childhood and their time-dependent patterns remain inconclusive. We used functional data analysis (FDA) to model temporal profiles of daily activity, measured objectively using accelerometers, to identify diurnal and seasonal PA patterns in a nationally representative sample of primary school-aged UK children. We hypothesised that PA levels would be lower in girls than boys at play times and after school, higher in children participating in social forms of exercise (such as sport or play), and lower among those not walking to school.
Children participating in the UK-wide Millennium Cohort Study wore an Actigraph GT1M accelerometer for seven consecutive days during waking hours. We modelled 6,497 daily PA profiles from singleton children (3,176 boys; mean age: 7.5 years) by means of splines, and used functional analysis of variance to examine the cross-sectional relation of time and place of measurement, demographic and behavioural characteristics to smoothed PA profiles.
Diurnal and time-specific patterns of activity showed significant variation by sex, ethnicity, UK country and season of measurement; girls were markedly less active than boys during school break times than boys, and children of Indian ethnicity were significantly less active during school hours (9:30-12:00). Social activities such as sport clubs, playing with friends were associated with higher level of PA in afternoon (15:00-17:30) and early evenings (17:30-19:30). Lower PA levels between 8:30-9:30 and 17:30-19:30 were associated with mode of travel to and from school, and number of cars in regular use in the household.
Diminished PA in primary school aged children is temporally patterned and related to modifiable behavioural factors. FDA can be used to inform and evaluate public health policies to promote childhood PA.
制定有效的增加体力活动（PA）策略需要了解儿童体力活动的时间特征。关于儿童期体力活动的决定因素及其时间依赖模式的证据尚无定论。我们使用功能数据分析（FDA）对通过加速度计客观测量的日常活动时间概况进行建模，以确定英国具有全国代表性的小学年龄儿童样本中的昼夜和季节性PA模式。我们假设，在玩耍时间和放学后，女孩的PA水平低于男孩；参与社交形式锻炼（如运动或玩耍）的儿童PA水平较高；而那些不步行上学的儿童PA水平较低。
参与全英国千禧队列研究的儿童在清醒时间连续七天佩戴Actigraph GT1M加速度计。我们通过样条对来自独生子女（3176名男孩；平均年龄：7.5岁）的6497份每日PA概况进行建模，并使用方差功能分析来检验测量时间和地点、人口统计学和行为特征与平滑后的PA概况之间的横断面关系。
活动的昼夜和特定时间模式在性别、种族、英国地区和测量季节方面存在显著差异；在课间休息时，女孩的活动明显少于男孩，印度裔儿童在上课时间（9:30 - 12:00）的活动明显较少。体育俱乐部、与朋友玩耍等社交活动与下午（15:00 - 17:30）和傍晚（17:30 - 19:30）较高的PA水平相关。8:30 - 9:30和17:30 - 19:30之间较低的PA水平与往返学校的出行方式以及家庭中经常使用的汽车数量有关。
小学年龄儿童PA减少具有时间模式，且与可改变的行为因素有关。FDA可用于为促进儿童PA的公共卫生政策提供信息并进行评估。
