The primary aim of this study was to test the validity of two accelerometers, CSA/MTI WAM-7164 and Actiwatch®, against direct observation of physical activity using the Children’s Physical Activity Form (CPAF). CSA/MTI WAM-7164 and Actiwatch accelerometers simultaneously measured activity during structured-play classes in 3- to 4-year olds. Accelerometry output was synchronized to CPAF assessments of physical activity in 78 children. Rank order correlations between accelerometry and direct observation evaluated the ability of the accelerometers to assess total physical activity. Within-child minute-to-minute correlations were calculated between accelerometry output and direct observation. For total physical activity, CSA/MTI output was significantly correlated with CPAF (r = .72, p < .001), but output from the Actiwatch was not (r = .16, p > .05).
Kelly, Reilly, and Paton are with the University of Glasgow Division of Developmental Medicine, Yorkhill Hospitals, Glasgow G38SJ, Scotland. Fairweather, now deceased, was also with the University Division of Developmental Medicine, Glasgow. Barrie is at Park House Farm, Nantwich, Cheshire, Cw5 7QX, England. Grant is with the University of Glasgow, NABS Division, Faculty of Biomedical and Life Sciences, Glasgow G128QQ, Scotland.