Affiliations: [a] Department of Physical Medicine and Rehabilitation,
University of Liege, 4000 Liege, Belgium
Note: [] Address for correspondence: C. Demoulin, University of Liege,
ISEPK (B21), Allée des Sports 4, B-4000 Liege, Belgium. Tel.: +32 4 366
39 47; Fax: +32 4 366 29 01; E-mail: adepaifve@ulg.ac.be
Abstract: The purpose of this study was to investigate the inter-session,
inter-tester and inter-site reproducibility of trunk muscle strength scores in
flexion, extension, lateral flexion and rotation. Ten healthy students were
tested on four apparatus with a 7–10 day break between sessions. The first two
sessions were identical while the other two differed either by the tester or by
the site. Furthermore, 10 patients with chronic low back dysfunction (CLBD)
were assessed with the four apparatus, once only. For all tests, CV ranged from
3.4% to 7.6% and from 3.9% to 8.1% in the inter-session and
inter-tester studies, respectively (p>0.05 except for
inter-session reproducibility of trunk flexor strength). Peak torque (PT) was
more variable from site to site with a CV ranging from 4.2% to 12.7%,
particularly in extension and left lateral flexion (p< 0.05). No
statistically significant difference in the strength ratios (flexion/extension,
right/left lateral-flexion and right/left rotation) were found between sessions
or testers (4.9% < CV < 9.7%. The inter-site
reproducibility of ratios was lower. Comparison between the CLBD patients and
the healthy subjects with regard to PT normalized to body weight indicated
significantly decreased performance for the former except for flexion and
rotation scores in males. We conclude that in the case of healthy subjects,
inter-session and inter-tester trunk strength measurements derived from these
devices are reproducible. The low inter-site reproducibility suggests that
caution should be exercised when interpreting findings originating from
different sites. The lower extension strength scores in CLBD patients test
lends some validity to the system. However, further studies focusing on
reproducibility and validity of this system in CLBD patients are critical
before any conclusion regarding their clinical viability may be drawn.
