Affiliations: Department of Physical Therapy and Rehabilitation
Sciences, College of Nursing and Health Professions, Drexel University,
Philadelphia, PA, USA | Franciscan Hospital for Children, Research Center for
Children with Special Health Care Needs, Brighton, MA, USA | Department of Pediatric Rehabilitation Medicine,
Franciscan Hospital for Children, Brighton, MA, USA | Queensland Institute of Technology, Institute of
Health and Biomedical Innovation, St Lucia, QLD, Australia
Note: [] Corresponding author: Margaret E. O'Neil, Drexel University,
Mail Stop 7502, 1601 Cherry Street, Phila, PA 19102, USA. Tel.: +1 267 359
5546; Fax: +1 267 359 5576; E-mail: moneil@drexel.edu
Abstract: PURPOSE: The purposes of this study were to: 1) establish
inter-instrument reliability between left and right hip accelerometer
placement; 2) examine procedural reliability of a walking protocol used to
measure physical activity (PA); and 3) confirm concurrent validity of
accelerometers in measuring PA intensity as compared to the gold standard of
oxygen consumption measured by indirect calorimetry. METHODS: Eight children (mean age: 11.9; SD: 3.2, 75% male) with CP
(GMFCS levels I–III) wore ActiGraph GT3X accelerometers on each hip and
the Cosmed K4b^{2} portable indirect calorimeter during two measurement
sessions in which they performed the six minute walk test (6MWT) at three
self-selected speeds (comfortable/slow, brisk, fast). Oxygen consumption (VO2)
and accelerometer step and activity count data were recorded. RESULTS: Inter-instrument reliability of ActiGraph GT3X
accelerometers placed on left and right hips was excellent
(ICC=0.96–0.99, CI_{95}: 0.81–0.99).
Reproducibility of the protocol was good/excellent (ICC=0.75–0.95,
CI_{95}: 0.75–0.98). Concurrent validity of
accelerometer count data and VO2 was fair/good (rho=0.67, p< 0.001). The
correlation between step count and VO2 was not significant (rho=0.29, p=0.2).
CONCLUSION: This preliminary research suggests that ActiGraph GT3X
accelerometers are reliable and valid devices to monitor PA during walking in
children with CP and may be appropriate in rehabilitation research and clinical
practice. ActiGraph GTX3 step counts were not valid for this sample and further
research is warranted.
