Agreement between activPAL and ActiGraph for assessing children's sedentary time

Area of Science:

• Pediatrics
• Kinesiology
• Public Health

Background:

• Accelerometers are used to measure children's sedentary time.
• Concerns exist whether sedentary time accurately reflects sitting time, a behavior linked to adverse health outcomes.
• Objective measurement of sitting and standing time in children is crucial for health research.

Purpose of the Study:

• To assess agreement between ActiGraph (AG) sedentary time cut-points and objectively measured sitting/standing time using activPAL (aP).
• To identify optimal AG cut-points for determining children's sitting and sitting plus standing time during school hours.

Main Methods:

• Forty-eight children (8-12 years) wore both AG and aP devices during school days.
• AG data were analyzed using 17 cut-points (50-850 counts·min-1) for sedentary time.
• aP data provided objective measures of sitting and sitting plus standing time.
• Agreement was assessed using limits of agreement, and optimal cut-points were identified via Receiver Operator Characteristic (ROC) analyses.

Main Results:

• The smallest bias between aP sitting time and AG sedentary time was observed at AG100 for school hours (-5.2 minutes).
• An optimal AG cut-point of 96 counts·min-1 was identified for estimating sitting time (AUC=0.75, sensitivity=71.7%, specificity=67.8%).
• No optimal cut-point was found for distinguishing sitting plus standing time (AUC=0.51).

Conclusions:

• An ActiGraph cut-point of 100 counts·min-1 provides reliable estimates of children's free-living sitting time during school hours.
• Higher accelerometer cut-points may be necessary to capture combined sitting and standing behaviors.