Calibration and cross-validation of a wrist-worn Actigraph in young preschoolers
Journal article, Peer reviewed
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- Artikler / Articles 
OriginalversjonPediatric Obesity. 2015, 10, 1- 6. 10.1111/j.2047-6310.2013.00213.x
Objective: To calibrate the Actigraph GT3X+ accelerometer for wrist-worn placement in young preschoolers by developing intensity thresholds for sedentary, low- and high-intensity physical activity. Furthermore, to cross-validate the developed thresholds in young preschoolers. Methods: Actigraph GT3X+ was used to measure physical activity during structured activities and free play in 38 children (15–36 months). Activity was video recorded and scored into sedentary, low- and high-intensity physical activity based on Children's Activity Rating Scale (CARS) and combined with accelerometer data using a 5 s epoch. Receiver operating characteristic analysis was used to develop intensity thresholds in 26 randomly selected children. The remaining 12 children were used for cross-validation. Results: Intensity thresholds for sedentary were ≤89 vertical counts (Y) and ≤221 vector magnitude (VM) counts per 5 s and ≥440 Y counts and ≥730 VM counts per 5 s for high-intensity physical activity. Sensitivity and specificity were 60–100% for the developed intensity thresholds. Strong correlations (Spearman rank correlation 0.69–0.91) were found in the cross-validation sample between the developed thresholds for the accelerometer and CARS scoring time in all intensity categories. Conclusion: The developed intensity thresholds appear valid to categorize sedentary behaviour and physical activity intensity categories in children 2 years of age.
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