A Calibration Protocol for Population-Specific Accelerometer Cut-Points in Children

Mackintosh, K.A., Fairclough, Stuart J., Stratton, G. and Ridgers, N.D. (2012) A Calibration Protocol for Population-Specific Accelerometer Cut-Points in Children. PLOS ONE, 7 (5). pp. 1-6. ISSN 1932-6203 DOI https://doi.org/10.1371/journal.pone.0036919

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Purpose To test a field-based protocol using intermittent activities representative of children's physical activity behaviours, to generate behaviourally valid, population-specific accelerometer cut-points for sedentary behaviour, moderate, and vigorous physical activity. Methods Twenty-eight children (46% boys) aged 10–11 years wore a hip-mounted uniaxial GT1M ActiGraph and engaged in 6 activities representative of children's play. A validated direct observation protocol was used as the criterion measure of physical activity. Receiver Operating Characteristics (ROC) curve analyses were conducted with four semi-structured activities to determine the accelerometer cut-points. To examine classification differences, cut-points were cross-validated with free-play and DVD viewing activities. Results Cut-points of ≤372, >2160 and >4806 counts•min−1 representing sedentary, moderate and vigorous intensity thresholds, respectively, provided the optimal balance between the related needs for sensitivity (accurately detecting activity) and specificity (limiting misclassification of the activity). Cross-validation data demonstrated that these values yielded the best overall kappa scores (0.97; 0.71; 0.62), and a high classification agreement (98.6%; 89.0%; 87.2%), respectively. Specificity values of 96–97% showed that the developed cut-points accurately detected physical activity, and sensitivity values (89–99%) indicated that minutes of activity were seldom incorrectly classified as inactivity. Conclusion The development of an inexpensive and replicable field-based protocol to generate behaviourally valid and population-specific accelerometer cut-points may improve the classification of physical activity levels in children, which could enhance subsequent intervention and observational studies.

Item Type: Article
Subjects: Q Science > Q Science (General)
Divisions: Sports Science
Date Deposited: 09 Nov 2015 15:08
URI: http://repository.edgehill.ac.uk/id/eprint/6527

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