Calibration and comparison of accelerometer cut points in preschool children.
OBJECTIVE
The present study aimed to develop accelerometer cut points to classify physical activities (PA) by intensity in preschoolers and to investigate discrepancies in PA levels when applying various accelerometer cut points.


METHODS
To calibrate the accelerometer, 18 preschoolers (5.8 ± 0.4 years) performed eleven structured activities and one free play session while wearing a GT1M ActiGraph accelerometer using 15 s epochs. The structured activities were chosen based on the direct observation system Children's Activity Rating Scale (CARS) while the criterion measure of PA intensity during free play was provided using a second-by-second observation protocol (modified CARS). Receiver Operating Characteristic (ROC) curve analyses were used to determine the accelerometer cut points. To examine the classification differences, accelerometer data of four consecutive days from 114 preschoolers (5.5 ± 0.3 years) were classified by intensity according to previously published and the newly developed accelerometer cut points. Differences in predicted PA levels were evaluated using repeated measures ANOVA and Chi Square test.


RESULTS
Cut points were identified at 373 counts/15 s for light (sensitivity: 86%; specificity: 91%; Area under ROC curve: 0.95), 585 counts/15 s for moderate (87%; 82%; 0.91) and 881 counts/15 s for vigorous PA (88%; 91%; 0.94). Further, applying various accelerometer cut points to the same data resulted in statistically and biologically significant differences in PA.


CONCLUSIONS
Accelerometer cut points were developed with good discriminatory power for differentiating between PA levels in preschoolers and the choice of accelerometer cut points can result in large discrepancies.
Department of Movement and Sport Sciences, University of Ghent, Ghent, Belgium. eveline.vancauwenberghe@ugent.be
Eveline
E
van Cauwenberghe
Valery
V
Labarque
Stewart G
SG
Trost
Ilse
I
de Bourdeaudhuij
Greet
G
Cardon
D056044:Actigraphy / Q000295:instrumentation* / Q000592:standards; D000367:Age Factors; D000704:Analysis of Variance; D001530:Belgium; D002138:Calibration; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity; D010988:Play and Playthings; D012372:ROC Curve; D015203:Reproducibility of Results; D012420:Running; D057185:Sedentary Behavior; D013997:Time Factors; D016138:Walking