Identification And Validity Of Accelerometer Cut-points In 1-3-year-old Toddlers

Physical activity (PA) at an early age has been linked to PA later in life. However, there are few validated methods to assess PA in toddlers (1 – 3 y). Due to the increased focus on simultaneously capturing all 24-h movement behaviors, measuring PA using a device already determined to be a valid measure of sleep in this age group would be beneficial, but the validity of these devices for measuring PA is unknown. PURPOSE: To determine the validity of cut-points for sedentary time (SED), light PA (LPA), and moderate-to-vigorous PA (MVPA) in toddlers using a sleep monitor. METHODS: Toddlers, 1 - 3 years, wore an accelerometer on the non-dominant ankle during a video-taped play period of at least 60-min (at least 30-min indoor and 30-min outdoor) at childcare or at home. Videos were later coded for PA intensity using the Observational System for Recording Physical Activity in Children – Preschool (OSRAC-P). Pearson’s correlation (r) was used to assess the relationship between the device’s proportional integrating measure (PIM) and directly observed (DO) PA intensity at a 15-s epoch. Receiver operating characteristic (ROC) curve analyses were performed to determine cut-points using a training sample (80% of overall sample). Predictive validity was assessed in a testing sample (20%). RESULTS: Thirty-two toddlers (mean age = 24 ± 7 months) were included in the study. Play was predominantly LPA (74%, 22% SED, 4% MVPA). Overall, PIM was moderately correlated with DO (r = 0.57). From the ROC curve analyses, the 15-s count ranges corresponding to SED, LPA, and MVPA were ≤ 1,468, 1,469 – 6,916, and ≥ 6,917 counts/15-s, respectively. In the training data, area under the curve was 0.77, percent accuracy was 61%, and sensitivity and specificity were 38-82% and 64-93%, respectively. When applied to the testing sample, percent agreement was 60%, and sensitivity and specificity were 48-79% and 64-94%, respectively. Validity was lowest for MVPA. CONCLUSION: The device used in the present study may be a valid method for capturing SED and LPA, but not MVPA, in toddlers. This device could be utilized to measure total PA. Other studies assessing PA in toddlers reported higher validity for ankle-worn (r = 0.75), or hip- and wrist-worn (r = 0.66 – 0.69) devices. Future research should assess 24-hour movement patterns in toddlers utilizing this device.