Altered hip muscle activation in patients with chronic non-specific low back pain

The aim of this study was to examine postural control in patients with chronic non-specific low back pain (CNRS). Furthermore the influence of visual information (eyes open versus eyes closed) was analyzed. A total of 8 patients with CNRS and 12 healthy control subjects were examined. Surface electromyography (SEMG) recordings were made from 5 trunk and 5 lower limb muscles as well as one hip muscle during application of distal lateral perturbation. Healthy controls (mean ± standard deviation: 96.42±64.77 µV) showed a significantly higher maximum amplitude of the gluteus medius muscle in comparison to patients with CNRS (56.29±39.63 µV). Furthermore activation of several lower limb muscles was found to be dependent on visual information. Patients showed an altered reflex response of the gluteus medius muscle which could be associated with reduced hip stability.