title: Measurement of cervical flexor endurance following whiplash.
abstract: OBJECTIVE
  To investigate measurement properties of a practical test of cervical flexor endurance (CFE) in whiplash patients including inter-rater reliability, sensitivity to clinical change, criterion related validity against the Neck Disability Index (NDI), and discriminant validity for injured versus uninjured populations.
  
  
  METHODS
  Two samples were recruited, 81 whiplash patients, and a convenience sample of 160 subjects who were not seeking treatment and met criteria for normal pain and range of motion. CFE was measured using a stopwatch while the subject, in crook lying, held their head against gravity to fatigue.
  
  
  RESULTS
  Inter-rater reliability in whiplash patients was in a range considered 'almost perfect' (Intraclass Correlation=0.96). CFE had greater inter-subject variability than the NDI or range of motion in any of three planes. However, the effect size for improvement in CFE over treatment was as large as the effect sizes for all of those measures. In multivariate regression, CFE changes accounted for changes on the NDI better than the three ranges of motion. CFE discriminated whiplash patients who were within six months of injury (n=71) from age and gender matched normals with high effect size (ES=1.5).
  
  
  CONCLUSIONS
  These findings provide evidence of reliability and validity for CFE measurement, and demonstrate that CFE detects clinical improvements. Variance on CFE emphasizes the need to consider inter-, and intra-subject standard deviations to interpret scores.
authors.affiliation: Department of Medicine, McMaster University and Center for Acute Injury Rehabilitation, St. Joseph's Hospital, Hamilton, Ontario, Canada. acinjury@stjosham.on.ca
authors.forename: Dinesh A
authors.initials: DA
authors.lastname: Kumbhare
authors.forename: Brad
authors.initials: B
authors.lastname: Balsor
authors.forename: William L
authors.initials: WL
authors.lastname: Parkinson
authors.forename: Peter
authors.initials: P
authors.lastname: Harding Bsckin
authors.forename: Michel
authors.initials: M
authors.lastname: Bedard
authors.forename: Alexandra
authors.initials: A
authors.lastname: Papaioannou
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Adachi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002170:Canada; D002574:Cervical Vertebrae; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D009334:Neck Muscles / Q000503:physiopathology*; D019547:Neck Pain / Q000503:physiopathology; D015588:Observer Variation; D010807:Physical Endurance / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D015203:Reproducibility of Results; D013997:Time Factors; D014911:Whiplash Injuries / Q000503:physiopathology* / Q000628:therapy