Use of accelerometers in a large field-based study of children: protocols, design issues, and effects on precision.
Journal of Physical Activity and Health 2008 ; 5 Suppl 1: S98-111.
PubMed ID : 18364528
PMCID : 0
Objective methods can improve accuracy of physical activity measurement in field studies but uncertainties remain about their use.
Children age 11 years from the Avon Longitudinal Study of Parents and Children (ALSPAC), were asked to wear a uni-axial accelerometer (MTI Actigraph) for 7 days.
Of 7159 children who attended for assessment, 5595 (78%) provided valid measures. The reliability coefficient for 3 days of recording was .7 and the power to detect a difference of 0.07 SDs (P
Objective measures of physical activity can be incorporated into large longitudinal studies of children.