Audy P. Hodselmans, Pieter U. Dijkstra, Cees van der Schans and Jan H. B. Geertzen
DOI: 10.2340/16501977-0014

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.
Subjects: 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 ≥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 ≥0. 75). The limits of agreement are substantial, indicating a considerable natural varia­tion between test-sessions for all psychophysical tests.
Conclusion: 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.