RMA DelaysOur Admin Portal website is currently experiencing technical difficulties, and it could result in delays with RMAs being processed. We are currently working to resolve these issues. We apologize for the inconvenience.
Join us on August 11th for an ActiGraph webinar hosted by Xtalks:
Oncology Research and Care: Reimagining Digital InnovationRegister Now
Calibration and validation of the ActiGraph GT3X+ in 2-3 year olds
- Published on Nov. 27, 2013
Objective To calibrate and validate the ActiGraph GT3X+ to measure sedentary behaviour (SB) and physical activity (PA) in 2-3 year olds, using 5-second epochs; and to compare the predictive validity of the resulting cut-points with that of NHANES’, Trost’s, and Pate’s 15-second cut-points.
Design Cross-sectional study
Method Eighteen children (2.86 ± 0.60years) wore an ActiGraph GT3X+ during video-recorded semi-structured calibration activity sessions. Activity was coded following Children’s Activity Rating Scale (CARS). Receiver-Operating Characteristic analysis was used to derive Axis1 and Vector Magnitude (VM) cut-points for SB and MVPA at 5-second epochs. Agreement with CARS was assessed with Cohen’s kappa, Lin’s concordance, and Bland-Altman plots. Predictive validity of all cut-points was assessed in an independent sample of 20 children (2.99 ± 0.48years) video-recorded during free-play, using the same procedures as the calibration phase.
Results During calibration, VM cut-points (SB≤96.12 counts; MVPA≥361.94 counts) showed slightly better classification agreement with CARS than Axis1 cut-points (SB≤5 counts; MVPA≥165 counts), but the latter showed the lowest bias in estimated SB and MVPA time. In the validation sample, 5-second Axis1 cut-points showed the best predictive validity and lowest mean differences of all cut-points between predicted and observed SB (-2.31%), light PA (-24.40%), and total PA time (-0.95%). MVPA time was significantly overestimated by all cut-points (128.33-184.17%).
Conclusions Because MVPA was highly overestimated, using only the 5-second Axis1 SB cut-point to distinguish SB from total PA is advised. The high accuracy indicates that these cut-points are useful for epidemiological studies involving the SB and PA of 2-3 year olds.