Resumen de Validation and Calibration of the Actical Accelerometer in Preschool Children

Maria J.C.A. Almeida, Kerry L. McIver, Karin A. Pfeiffer, Marsha Dowda, Russell R. Pate

• Purpose: Decreased physical activity (PA) is likely a contributor to the rising prevalence of obesity in children. Lack of valid and acceptable measures of PA has been an issue in studies involving young children. The Actical accelerometer is a promising tool for measurement of PA in young children. The purpose of this study was to calibrate and validate the Actical accelerometer for use with 3- to 5-yr-old children.

  Methods: Eighteen preschool children wore an Actical accelerometer and a Cosmed portable metabolic system during a period of rest, while performing three structured activities in a laboratory setting (used for calibration), and during 20 min each of unstructured indoor and outdoor activities at their preschool (used for cross-validation). Expired respiratory gases were collected, and oxygen consumption was measured on a breath-by-breath basis. Accelerometer data were collected in 15-s intervals.

  Results: For the accelerometer calibration, the correlation between [latin capital V with dot above]O2 and counts was r = 0.89 across all activities. The calibration equation established was [latin capital V with dot above]O2 = counts[middle dot]15 s-1 (0.01437) + 9.73 (R2 = 0.96, SEE = 3.02). The cut-point for moderate activity (20 mL[middle dot]kg-1[middle dot]min-1) was 715 counts[middle dot]15 s-1 (sensitivity 97.2%, specificity 91.7%), and the cut-point for vigorous activity (30 mL[middle dot]kg-1[middle dot]min-1) was 1411 counts[middle dot]15 s-1 (sensitivity 98.2%, specificity 61.1%). For the cross-validation, the intraclass correlation coefficient was R = 0.59 and the Spearman correlation coefficient was R = 0.80 (P < 0.001) between measured and predicted [latin capital V with dot above]O2. Percentage of agreement, kappa, and modified kappa for moderate activity were 0.73, 0.40, and 0.46, respectively. For vigorous activity, the same measures were 0.85, 0.26, and 0.71, respectively.

  Conclusion: The Actical accelerometer is a valid tool for measuring PA in young children