Measurement of physical activity in preschool children.

PURPOSE: To provide an overview of the methods that have been developed for measurement of physical activity in children of preschool age. Emphasis will be given to direct observation and accelerometry, but pedometry, HR monitoring, and proxy reports will be reviewed as well.
METHOD: Research articles detailing the measurement properties of direct observational systems, accelerometry, pedometry, HR monitoring, and proxy reporting specifically in children of preschool age were selected and reviewed.
RESULTS: Systems for direct observation of physical activity and accelerometry are valid and reliable measures of physical activity in young children. Direct observation, which can provide information on type and context of physical activity, is an excellent complement to accelerometry, which provides detailed information on the intensity and duration of physical activity but no contextual information.
CONCLUSIONS: Direct observation systems and accelerometry have become well-established measurements of physical activity in young children as well as older groups. Pedometry and HR monitoring have been shown to be applicable, but these methods have been studied less extensively than direct observation and accelerometry. Proxy reports of physical activity are attractive because of low burden, but they have limited validity.