Comparing accelerometer cut-points in youth with physical disabilities


Background: Objective measures of physical activity (PA) and sedentary behaviour (SB) are common. However, the value of using objective measures and associated cut-points to accurately capture PA and SB in youth with mobility limitations is uncertain. Purpose: To compare PA and SB among youth with physical disabilities (YPD) based on existing accelerometry cut-points. Methods: 34 YPD aged 12 to 21 years who were either ambulatory or used assistive devices wore the Actigraph® GT3X accelerometer on the wrist over a 7-day period. Daily minutes of SB and PA (light, moderate, and vigorous) were collected and analyzed using the ActiLife software. All data were comparatively evaluated using cut-points for wrist-worn accelerometers in children and youth (Crouter et al. 2016), and hip-based cut-points developed for children and youth with chronic health conditions (Stephens et al. 2016). Results: Mean daily minutes of SB and light PA were higher when data were analyzed using the Crouter (Mean SB= 412 ± 129; Mean light PA= 200 ± 59) versus Stephens (Mean SB= 345 ± 125; Mean light PA= 91 ± 28) cut-points. Mean daily minutes of moderate and vigorous PA calculated using Stephens' cut-points were higher (Mean moderate PA= 162 ± 48; Mean vigorous PA= 167 ± 98) when compared to Crouter's cut-points (Mean moderate PA= 143 ± 72; Mean vigorous PA= 13 ± 13). Conclusion: These results demonstrate the uncertainty that exists when selecting appropriate cut-points to track SB and PA in YPD. Consideration must be given to the wear location of accelerometers as well as the practicality of applying cut-points that have not been calibrated in YPD.

Acknowledgments: Social Sciences and Humanities Research Council of Canada