title: Test-retest reliability of psychophysical lift capacity in patients with non-specific chronic low back pain and healthy subjects.
abstract: OBJECTIVE
  Psychophysical lift capacity tests are lifting tests in which the performance, expressed in Newtons, is divided by the perceived exertion, expressed on a Borg scale. The aim of this study was to analyse test-retest reliability of psychophysical lift capacity tests.
  
  
  METHODS
  Patients with non-specific chronic low back pain (n=20) and healthy subjects (n=20).
  
  
  METHODS
  Psychophysical lift capacity tests were assessed during a back school intake at the Centre for Rehabilitation of the University Medical Centre Groningen. Patients on the waiting list and healthy subjects were assessed twice, with a 2-week interval between assessments. Intra-class correlation (ICC) was calculated as a measure of reliability. An ICC > or = 0.75 was considered as an acceptable reliability. Limits of agreement as a measure for natural variation were calculated.
  
  
  RESULTS
  The psychophysical static and dynamic lift capacity tests showed good reliability (ICC > or = 0.75). The limits of agreement are substantial, indicating a considerable natural variation between test-sessions for all psychophysical tests.
  
  
  CONCLUSIONS
  The psychophysical static lift capacity and dynamic lifting capacity are reliable instruments for patients with non-specific chronic low back pain and healthy subjects. However, a substantial amount of natural variation should be taken into account between 2 test sessions when interpreting the test results clinically.
authors.affiliation: Hanze University Groningen School of Health Care Studies, Department of Physiotherapy, Eyssoniusplein 18, Groningen, The Netherlands. a.p.hodselmans@pl.hanze.nl
authors.forename: Audy P
authors.initials: AP
authors.lastname: Hodselmans
authors.forename: Pieter U
authors.initials: PU
authors.lastname: Dijkstra
authors.forename: Cees
authors.initials: C
authors.lastname: van der Schans
authors.forename: Jan H B
authors.initials: JH
authors.lastname: Geertzen
mesh_terms: D000328:Adult; D002908:Chronic Disease; D005260:Female; D006801:Humans; D017770:Lifting; D017116:Low Back Pain / Q000503:physiopathology / Q000523:psychology / Q000534:rehabilitation*; D008297:Male; D005082:Physical Exertion / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology; D011601:Psychophysics / Q000295:instrumentation; D015203:Reproducibility of Results