title: Reliability and validity of daily physical activity measures during inpatient spinal cord injury rehabilitation.
abstract: OBJECTIVE
  To assess the test-retest reliability and convergent validity of daily physical activity measures during inpatient spinal cord injury rehabilitation.
  
  
  METHODS
  Observational study.
  
  
  METHODS
  Two inpatient spinal cord injury rehabilitation centres.
  
  
  METHODS
  Participants (n = 106) were recruited from consecutive admissions to rehabilitation.
  
  
  METHODS
  Physical activity during inpatient spinal cord injury rehabilitation stay was recorded on two days via (1) wrist accelerometer, (2) hip accelerometer if ambulatory, and (3) self-report (Physical Activity Recall Assessment for People with Spinal Cord Injury questionnaire). Spearman's correlations and Bland-Altman plots were utilized for test-retest reliability. Correlations between physical activity measures and clinical measures (functional independence, hand function, and ambulation) were performed.
  
  
  RESULTS
  Correlations for physical activity measures between Day 1 and Day 2 were moderate to high (ρ = 0.53-0.89). Bland-Altman plots showed minimal bias and more within-subject differences in more active individuals and wide limits of agreement. None of these three physical activity measures correlated with one another. A moderate correlation was found between wrist accelerometry counts and grip strength (ρ = 0.58) and between step counts and measures of ambulation (ρ = 0.62). Functional independence was related to wrist accelerometry (ρ = 0.70) and step counts (ρ = 0.56), but not with self-report.
  
  
  CONCLUSIONS
  The test-retest reliability and convergent validity of the instrumented measures suggest that wrist and hip accelerometers are appropriate tools for use in research studies of daily physical activity in the spinal cord injury rehabilitation setting but are too variable for individual use.
authors.affiliation: Rehabilitation Research Lab, GF Strong Rehabilitation Centre, The University of British Columbia, Vancouver, BC, Canada.
authors.forename: Dominik
authors.initials: D
authors.lastname: Zbogar
authors.affiliation: Rehabilitation Research Lab, GF Strong Rehabilitation Centre, The University of British Columbia, Vancouver, BC, Canada.
authors.forename: Janice J
authors.initials: JJ
authors.lastname: Eng
authors.affiliation: The University of British Columbia, Vancouver, BC, Canada.
authors.forename: William C
authors.initials: WC
authors.lastname: Miller
authors.affiliation: International Collaboration on Repair Discoveries, The University of British Columbia, Vancouver, BC, Canada.
authors.forename: Andrei V
authors.initials: AV
authors.lastname: Krassioukov
authors.affiliation: Department of Physical Therapy, University of Toronto, Toronto, ON, Canada.
authors.forename: Mary C
authors.initials: MC
authors.lastname: Verrier
keywords: Spinal cord injury; accelerometry; rehabilitation; reliability; self-reported physical activity; step counts; validity