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

Area of Science:

• Biomedical Engineering
• Kinesiology
• Pediatric Health

Background:

• Accurate measurement of physical activity and sedentary behavior is crucial for understanding child health.
• Wearable sensors like activPAL are commonly used to assess physical activity in children, but their accuracy needs validation in this population.

Purpose of the Study:

• To evaluate the classification accuracy of the activPAL device for sedentary behavior (SB) and posture in 4- to 6-year-old children.
• To assess the device's accuracy in measuring total time spent sedentary and the total number of breaks in SB.

Main Methods:

• Forty children aged 4-6 years participated in a laboratory protocol with direct observation of posture (sit/lie, stand, walk, other).
• Posture classification was performed using activPAL software, with accuracy evaluated using sensitivity, specificity, and ROC-AUC.
• Paired sample t-tests compared activPAL data with direct observation for time spent in postures and SB breaks.

Main Results:

• The activPAL demonstrated good classification accuracy for sitting (ROC-AUC = 0.84) and fair accuracy for standing (0.76) and walking (0.73).
• Time spent sitting/lying and standing was overestimated by 5.9% and 14.8%, respectively; walking was underestimated by 10.0%.
• The total number of sedentary behavior breaks was significantly overestimated by the activPAL (55 ± 27 breaks; p < .01).

Conclusions:

• The activPAL shows good performance in classifying basic postures like sitting in young children.
• The device struggles with classifying less common postures (e.g., kneeling) and exhibits inaccuracies in quantifying time spent in different postures and sedentary breaks.
• While useful, the activPAL's limitations in accuracy for specific postures and sedentary behavior metrics should be considered when used with young children.