Validation of activPALTM defined sedentary time and breaks in sedentary time in 4- to 6-year-olds

This study examined the classification accuracy of the activPALTM, 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 activPALTM 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 activPALTM 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±27 over the course of the protocol; p<0.01). The activPALTM performed well when classifying postures in young children. However, the activPALTM has difficulty classifying ‘other’ postures, such as kneeling. In addition, when predicting time spent in different postures and total number of breaks in SB the activPALTM appeared not to be accurate.