Correlation of chronic low-back pain behavior and muscle function examination of the flexion-relaxation response.

The relationship between videotape ratings of pain behavior and the flexion-relaxation phenomenon was evaluated in a sample of 39 chronic low-back pain patients. The results showed that guarded movement explained approximately 27% of the variability in the flexion-relaxation phenomenon, adjusting for pain intensity rating. There were no significant differences in sex observed. It is recommended that clinicians pay close attention to qualitative aspects of patient behavior to improve the sensitivity of the physical examination in detecting bona fide impairment.