Publication Details

Janssen, X., Cliff, D. P., Reilly, J. J., Hinkley, T., Jones, R. A., Batterham, M., Ekelund, U., Brage, S. & Okely, A. D. (2014). Validation of activPALTM defined sedentary time and breaks in sedentary time in 4- to 6-year olds.. Pediatric Exercise Science, 26 (1), 110-117.


This study examined the classification accuracy of the activPAL™, including total time spent sedentary and total number of breaks in sedentary behavior (SB) in 4-6 year old children. Forty children aged 4-6 years (5.3±1.0 years) completed a ~150-min laboratory protocol involving sedentary, light and moderate-to vigorous-intensity activities. Posture was coded as sit/lie, stand, walk or 'other' using direct observation. Posture was classified using the activPAL™ software. Classification accuracy was evaluated using sensitivity, specificity and area under the receiver operating characteristic curve (ROC-AUC). Time spent in each posture and total number of breaks in SB were compared using paired sample t-tests. The activPAL™ showed good classification accuracy for sitting (ROC-AUC=0.84) and fair classification accuracy for standing and walking (0.76 and 0.73, respectively). Time spent in sit/lie, and stand was overestimated by 5.9% (95% CI=0.6%-11.1%) and 14.8% (11.6%-17.9%), respectively; walking was underestimated by 10.0% (-12.9%--7.0%). Total number of breaks in SB were significantly overestimated (55±27over the course of the protocol; p