Physical Activity in Preschool Children

描述（由申请人提供）：学龄前儿童的肥胖率正在上升，而体育活动的减少可能是造成这一令人不安趋势的原因。数以百万计的美国儿童每天在正规的学前班环境中度过几个小时，但人们对学前班儿童的身体活动水平知之甚少。该调查旨在描述学龄前儿童的身体活动行为，并确定影响学龄前儿童身体活动的物质和社会环境因素以及制度资源、政策和实践。研究将在24所有执照的幼儿园进行，研究对象为3-5岁的720名儿童（每所学校30名儿童）。将使用两种客观方法测量每个儿童的身体活动：加速度计（运动传感器）和直接观察。每个孩子将在5天的学前班上学时间（至少4小时）佩戴单轴加速度计，原始加速度计数据将用于计算不活动的分钟数以及轻度、中度和剧烈体育活动的分钟数。此外，一个观察系统将用于测量儿童的身体活动和假设的社会和环境对身体活动的影响。每个孩子将被观察6小时（12个30分钟的时间段）。机构资源、政策和实践将通过与学校人员的结构化访谈、学校资源的直接测量（例如，操场尺寸）和幼儿教育评定量表（ECERS-R）的管理来衡量。将采用横断面观察性研究设计。为了描述中度至剧烈身体活动（MVPA）与假设影响MVPA的因素之间的关联，将进行一系列混合模型分析。这些分析将把学前教育作为一种随机效应，以解释学前教育中儿童完整的社会群体。此外，还将进行多变量分析，包括个人和学校水平的自变量。拟议的研究将通过为今后的干预研究和制定有效的公共政策奠定基础，解决一个关键的公共卫生问题，即儿童肥胖日益普遍。

DESCRIPTION (provided by applicant): Obesity rates are increasing in children of preschool age, and decreased physical activity is a likely contributor to this troubling trend. Millions of American children spend several hours per day in formal preschool settings, but little is known about the physical activity levels of children in preschools. The proposed investigation is designed to describe the physical activity behaviors of children in preschools and to identify the physical and social environmental factors as well as the institutional resources, policies and practices that influence physical activity in children attending preschools. The research will be conducted in 24 licensed preschools, and subjects will be 720 children in the 3-5 year age range (30 children per school). Physical activity will be measured in each child using two objective methods: accelerometry (motion sensors) and direct observation. Each child will wear a uniaxial accelerometer during his/her hours of preschool attendance (at least 4 hours) on five days, and raw accelerometer data will be used to calculate minutes of inactivity and minutes of light, moderate, and vigorous physical activity. Also, an observational system will be used to measure the child's physical activity and hypothesized social and environmental influences on physical activity. Each child will be observed for a total of 6 hours (twelve 30-minute periods). Institutional resources, policies, and practices will be measured by structured interviews with school personnel, by direct measures of school resources (e.g., playground dimensions), and by administration of the Early Childhood Education Rating Scale (ECERS-R). A cross-sectional, observational study design will be used. To describe associations between moderate to vigorous physical activity (MVPA) and the factors that are hypothesized to influence MVPA a series of mixed model analyses will be performed. These analyses will include preschool as a random effect to account for the intact social grouping of children within preschools. Also, multivariate analyses including both individual and school level independent variables will be performed. The proposed study will address a critical public health problem, the increasing prevalence of obesity in children, by laying the groundwork for future intervention studies and for development of effective public policies.