Decision trees for detection of activity intensity in youth with cerebral palsy

Trost, Stewart G., Fragala-Pinkham, Maria A., Lennon, Nancy, & O'Neil, Margaret E. (2016) Decision trees for detection of activity intensity in youth with cerebral palsy. Medicine and Science in Sports and Exercise, 48(5), pp. 958-966.

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  • To develop and test decision tree (DT) models to classify physical activity (PA) intensity from accelerometer output and Gross Motor Function Classification System (GMFCS) classification level in ambulatory youth with cerebral palsy (CP); and 2) compare the classification accuracy of the new DT models to that achieved by previously published cut-points for youth with CP.


  • Youth with CP (GMFCS Levels I - III) (N=51) completed seven activity trials with increasing PA intensity while wearing a portable metabolic system and ActiGraph GT3X accelerometers. DT models were used to identify vertical axis (VA) and vector magnitude (VM) count thresholds corresponding to sedentary (SED) (<1.5 METs), light PA (LPA) (>/=1.5 and <3 METs) and moderate-to-vigorous PA (MVPA) (>/=3 METs). Models were trained and cross-validated using the 'rpart' and 'caret' packages within R.


  • For the VA (VA_DT) and VM decision trees (VM_DT), a single threshold differentiated LPA from SED, while the threshold for differentiating MVPA from LPA decreased as the level of impairment increased. The average cross-validation accuracy for the VC_DT was 81.1%, 76.7%, and 82.9% for GMFCS levels I, II, and III, respectively. The corresponding cross-validation accuracy for the VM_DT was 80.5%, 75.6%, and 84.2%, respectively. Within each GMFCS level, the decision tree models achieved better PA intensity recognition than previously published cut-points. The accuracy differential was greatest among GMFCS level III participants, in whom the previously published cut-points misclassified 40% of the MVPA activity trials.


  • GMFCS-specific cut-points provide more accurate assessments of MVPA levels in youth with CP across the full spectrum of ambulatory ability.

Impact and interest:

2 citations in Scopus
3 citations in Web of Science®
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ID Code: 92459
Item Type: Journal Article
Refereed: Yes
DOI: 10.1249/MSS.0000000000000842
ISSN: 0195-9131
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2015 Lippincott, Williams & Wilkins
Deposited On: 31 Jan 2016 23:25
Last Modified: 26 Jun 2017 23:01

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