Comparison of Actiwatch® activity monitor and Children's Activity Rating Scale in children

The Children's Activity Rating Scale (CARS) is a rating scale that is used in direct observation of physical activity in children. Direct observation is costly and tedious, and accuracy may decrease as the observation period lengthens. Recently, motion sensors have gained acceptance for assessment of physical activity. The purpose of this study was to compare 6 h of activity levels using simultaneous monitoring of preschool aged children with CARS and the Actiwatch (Mini-mitter Company Inc.) activity monitor. A total of 40 children had 5-6 h (mean of 5.9 h) of direct observation while wearing a monitor on the waist. Simultaneous 3-min mean CARS scores and 3-min activity counts were matched for each subject. The range for the mean 3-min CARS scores ranged from 1.00 to 4.50. The 3-min activity counts ranged from 0 to 9,695 with a mean of 670 (median 243). The within child correlations between the 3-min CARS score and the 3-min sensor readings ranged from 0.03 to 0.92 (median of 0.74). We found the correlation coefficients were higher in those children who were more active, probably due to the larger ranges in the CARS scores. When using mixed model repeated measures, sensor readings were significantly associated with CARS (P < 0.001). Our results indicate that the 3-min CARS score correlates with 3-min activity counts, favoring the use of the activity monitors in assessing physical activity in preschool-aged children.