title: Reproducibility in measuring physical activity in children and adolescents with an acquired brain injury.
abstract: OBJECTIVE
  To examine the reproducibility in measurement of physical activity performance using the ActiGraph®GT3X+ accelerometer in children aged 8-16 years with Acquired Brain Injury (ABI).
  
  
  METHODS
  Reproducibility of standardized tasks: Thirty-two children with ABI (12 years 1 month, SD = 2 years 4 months; 20 males; Gross Motor Function Classification System I = 17, II = 15) performed the following activities on 2 consecutive days while wearing an accelerometer and a heart rate monitor: quiet sitting, slow walking (SW), moderate walking (MW), fast walking (FW) and rapid stepping on/off a block (STEP). Intra-class correlation coefficients (ICC) were calculated. Performance variability: Fifty-one participants (12 years 1 month, SD = 2 years 5 months; 27 males; GMFCS I = 26, II = 25) wore an accelerometer for 4 days in the community and reliability coefficients were calculated using standardized 12-hour time spent in moderate-to-vigorous physical activity (MVPA).
  
  
  RESULTS
  Test-re-test reproducibility was excellent for all activities (SW, ICC = 0.90; MW, ICC = 0.83; FW, ICC = 0.91; STEP, ICC = 0.89). Three days of monitoring produced excellent variability estimates of MVPA (R = 0.78).
  
  
  CONCLUSIONS
  Therapists can confidently use accelerometry as a reproducible measure of physical activity under standardized walking and stepping conditions, as well as in the community for children with ABI.
authors.affiliation: a Queensland Cerebral Palsy and Rehabilitation Research Centre, UQ Child Health Research Centre, Faculty of Medicine and Biomedical Sciences , The University of Queensland , Brisbane , Australia.
authors.forename: Emmah
authors.initials: E
authors.lastname: Baque
authors.affiliation: a Queensland Cerebral Palsy and Rehabilitation Research Centre, UQ Child Health Research Centre, Faculty of Medicine and Biomedical Sciences , The University of Queensland , Brisbane , Australia.
authors.forename: Lee
authors.initials: L
authors.lastname: Barber
authors.affiliation: a Queensland Cerebral Palsy and Rehabilitation Research Centre, UQ Child Health Research Centre, Faculty of Medicine and Biomedical Sciences , The University of Queensland , Brisbane , Australia.
authors.forename: Leanne
authors.initials: L
authors.lastname: Sakzewski
authors.affiliation: a Queensland Cerebral Palsy and Rehabilitation Research Centre, UQ Child Health Research Centre, Faculty of Medicine and Biomedical Sciences , The University of Queensland , Brisbane , Australia.
authors.forename: Roslyn N
authors.initials: RN
authors.lastname: Boyd
mesh_terms: D061725:Accelerometry; D000293:Adolescent; D000704:Analysis of Variance; D001930:Brain Injuries / Q000150:complications*; D002648:Child; D015444:Exercise / Q000502:physiology*; D005260:Female; D020233:Gait Disorders, Neurologic / Q000209:etiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology; D015203:Reproducibility of Results; D013223:Statistics as Topic; D016138:Walking / Q000502:physiology
keywords: Physical activity; accelerometer; acquired brain injury; adolescents; children