Affiliations: [a] Department of Physical Therapy, Multidisciplinary
Rehabilitation Centre, Nicosia, Cyprus | [b] Cyprus Sport Research Centre, Cyprus | [c] Technological Educational Institute Thessaloniki,
Greece
Abstract: Introduction: There is minimal information in the literature
concerning the intramachine reliability of the new Isokinetic dynamometer
Con-Trex MJ, and the intermachine reproducibility of this instrument with the
Cybex Norm isokinetic dynamometer. Objective: The purpose of this study was to provide some insight
with regard to the reproducibility of Con-Trex MJ in measuring the knee muscle
performance in flexion and extension (concentric) and to compare the
variability of measurement between Con-Trex and Cybex Norm. Methods: 35 (70 legs) male subjects with no previous history of any
knee pathology volunteered for the study. Intramachine reproducibility was
evaluated by assessing 30 legs twice on the Con-Trex MJ, within 2 to 7 days, at
angular velocities of 60°, 180° and 300°/sec.
Intermachine reproducibility was evaluated by assessing 40 legs randomly on the
Con-Trex MJ and Cybex Norm within 2 to 7 days at 60° and
180°/sec. Coefficient of variation (CV) was used to determine the
reproducibility of repeated measurements at $p< 0.01$. Results: Intra: The
variability of measurements of Con-Trex for Peak Torque, was 5.19–5.68% for
extension and 4.84–7.33% for flexion depending on the angular velocity. This
is acceptable for clinical and research studies. Inter: Between the two
Isokinetic devices there was a greater CV for Peak Torque ranging 7.28–9.17%
for extension and 8.54–15.84% for flexion. Conclusion: Based on the results of the present study, comparisons
of results between the two devices may not be valid. The results for knee
flexion and extension measurements at 60° and 180°/sec
recorded with Con-Trex were consistently greater than the values recorded with
the Cybex Norm.
