Article

Trunk motor behavior has been reported to be altered in low-back pain. This may
be associated with impaired lumbar proprioception, which could be compensated by
trunk stiffening. We assessed trunk control by measuring center-of-pressure,
lumbar kinematics and trunk muscle electromyography in 20 low-back pain patients
and 11 healthy individuals during a seated balancing task, in conditions with and
without disturbance of lumbar proprioception and occlusion of vision. We
hypothesized that low-back pain patients show larger postural sway, but smaller
thoraco-lumbar movements than healthy individuals. Repeated measures analyses of
variance indicated that the effects of proprioception disturbance and vision
occlusion were similar between groups. Interestingly, low-back pain patients
grabbed the safety rail more often, while differences between groups in sway
measures were rather subtle. This suggests that low-back pain patients were more
cautious. Furthermore, low-back pain patients had an about 20 degrees less flexed
lumbar posture than healthy individuals, and, in contrast to our hypothesis, made
larger thoraco-lumbar movements in the sagittal plane, as indicated by higher SDs
of thoraco-lumbar flexion and lower (more negative) correlations between pelvis
and thorax movements. Activation of the intersegmental longissimus relative to
the iliocostalis muscle, which spans all lumbar segments, was lower in low-back
pain patients compared to healthy individuals. This difference in muscle
activation may be causal for larger thoraco-lumbar movements, and may be
causative of reduced control over segmental lumbar movement, but may also reflect
the need for larger corrective movements to compensate balance impairments.
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Langue : ANGLAIS