Peak torque substantially varies between patients with non-specific low back pain; belong to directional preference classification, and healthy individuals—clinical biokinesiologic perspectives

[Purpose] To compare flexion and extension peak torque of patients with nonspecific-chronic low back pain who were classified as directional preference subgroups, and their matched healthy controls. [Participants and Methods] Fifty male volunteers (25 with non-specific chronic low back pain and 25 healthy-matched controls) consented to participate. The investigator collected all demographic data, hips, knees and spinal mobility in addition to the peak torque using the Biodex isokinetic dynamometer. The measurement protocol consisted of 2 sets of 10 consecutive flexion-extension efforts performed at 120°/sec and 60°/sec angular velocity. A two minutes rest period was given between sets. The preset 50° range of motion included 20°(+20°) of trunk extension and 30°(-30°) of trunk flexion. [Results] A 2 × 2 mixed-design ANOVA showed a significant group X isokinetic velocity interaction. The main effect of isokinetic velocity was also significant. In reference to the peak torque of the flexors of the trunk, the main effect of group was significant. [Conclusion] The extension peak torque significantly depends on the velocity of the isokinetic dynamometer; however the flexion peak torque significantly depends on the participants' group attribution.