title: The intra- and inter-rater reliability of five clinical muscle performance tests in patients with and without neck pain.
abstract: BACKGROUND
  This study investigates the reliability of muscle performance tests using cost- and time-effective methods similar to those used in clinical practice. When conducting reliability studies, great effort goes into standardising test procedures to facilitate a stable outcome. Therefore, several test trials are often performed. However, when muscle performance tests are applied in the clinical setting, clinicians often only conduct a muscle performance test once as repeated testing may produce fatigue and pain, thus variation in test results. We aimed to investigate whether cervical muscle performance tests, which have shown promising psychometric properties, would remain reliable when examined under conditions similar to those of daily clinical practice.
  
  
  METHODS
  The intra-rater (between-day) and inter-rater (within-day) reliability was assessed for five cervical muscle performance tests in patients with (n = 33) and without neck pain (n = 30). The five tests were joint position error, the cranio-cervical flexion test, the neck flexor muscle endurance test performed in supine and in a 45°-upright position and a new neck extensor test.
  
  
  RESULTS
  Intra-rater reliability ranged from moderate to almost perfect agreement for joint position error (ICC ≥ 0.48-0.82), the cranio-cervical flexion test (ICC ≥ 0.69), the neck flexor muscle endurance test performed in supine (ICC ≥ 0.68) and in a 45°-upright position (ICC ≥ 0.41) with the exception of a new test (neck extensor test), which ranged from slight to moderate agreement (ICC = 0.14-0.41). Likewise, inter-rater reliability ranged from moderate to almost perfect agreement for joint position error (ICC ≥ 0.51-0.75), the cranio-cervical flexion test (ICC ≥ 0.85), the neck flexor muscle endurance test performed in supine (ICC ≥ 0.70) and in a 45°-upright position (ICC ≥ 0.56). However, only slight to fair agreement was found for the neck extensor test (ICC = 0.19-0.25).
  
  
  CONCLUSIONS
  Intra- and inter-rater reliability ranged from moderate to almost perfect agreement with the exception of a new test (neck extensor test), which ranged from slight to moderate agreement. The significant variability observed suggests that tests like the neck extensor test and the neck flexor muscle endurance test performed in a 45°-upright position are too unstable to be used when evaluating neck muscle performance.
authors.affiliation: Institute of Sports Science and Clinical Biomechanics, The University of Southern Denmark, Odense, Denmark. tjsorensen@health.sdu.dk.
authors.forename: Tina
authors.initials: T
authors.lastname: Juul
authors.forename: Henning
authors.initials: H
authors.lastname: Langberg
authors.forename: Flemming
authors.initials: F
authors.lastname: Enoch
authors.forename: Karen
authors.initials: K
authors.lastname: Søgaard
mesh_terms: D000328:Adult; D064131:Back Muscles / Q000502:physiology*; D001696:Biomechanical Phenomena; D003718:Denmark; D005240:Feasibility Studies; D005260:Female; D019416:Head Movements; D006801:Humans; D007596:Joints / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D009334:Neck Muscles / Q000503:physiopathology*; D019547:Neck Pain / Q000175:diagnosis* / Q000503:physiopathology; D015588:Observer Variation; D010147:Pain Measurement; D056888:Patient Positioning; D010807:Physical Endurance; D010808:Physical Examination / Q000379:methods*; D011237:Predictive Value of Tests; D011434:Proprioception; D011594:Psychometrics; D015203:Reproducibility of Results; D016683:Supine Position; D055815:Young Adult