Behaviour-based movement cut-off points in 3-year old children comparing wrist- with hip-worn actigraphs MW8 and GT3X

Behaviour-based physical intensity evaluation requires rigorous calibration before application in long-term recordings of children’s sleep/activity patterns. This study aimed at:

(i) calibrating activity counts of motor behaviour measured simultaneously with MotionWatch 8 (MW8) and ActiGraph (GT3X) in 3-year-old children

(ii) documenting movement intensities in 30s-epochs at wrist/hip positions, and

(iii) evaluating the accuracy of cut-off agreements between different behavioural activities.

Thirty 3-year-old children of the NorthPop cohort performed six directed behavioural activities individually, each for 8–10 minutes while wearing two pairs of devices at hip and wrist positions. These naturally-occurring behaviours were aligned to movement intensities from ‘motionless’ (watching cartoons) and ‘sedentary’ (recumbent story listening, sit and handcraft) to ‘light activity’ (floor play with toys), ‘moderate activity’ (engaging in a brisk walk) and ‘vigorous activity (a sprinting game). Sprinting, floorball/walk and play on the floor with toys assigned as ‘physically mobile’ classes achieved outstanding accuracy, and two sedentary and motionless activities assigned to ‘physically stationary’ classes achieved excellent accuracy.

This calibration provides useful cut-offs for physical activity levels of preschool children. Contextual information of behaviour is advantageous because interventions will likely focus on behaviour-allocated time to reduce a sedentary lifestyle.