Relationship between onset of trunk muscle activities and pelvic kinematics in individuals with and without chronic low back pain.

Background: Lumbopelvic movement patterns during prone hip extension has been proposed as a clinical screening method for trunk muscle dysfunction in patients with chronic low back pain (CLBP). However, correlations between trunk muscle onset and pelvic kinematics have not been investigated.

Objective: To examine the correlation between trunk muscle onset and pelvic kinematics during prone hip extension in participants with CLBP.

Methods: Fifteen patients with CLBP and 15 healthy individuals participated. We evaluated the muscle activities of the lumbar multifidus, the longissimus, and the semitendinosus via electromyogram and the displacement angles of the pelvic tilt, oblique and rotation.

Results: The onset of the multifidus at the ipsilateral side of hip extension was significantly delayed in the patients with CLBP compared to the control group (P< 0.001). The onset of the ipsilateral multifidus in the control group was significantly correlated with increased anterior pelvic tilt angle (P= 0.019, r= 0.597), whereas no significant correlation was observed in the CLBP group (P= 0.810, r=-0.068).

Conclusion: The results suggest that pelvic kinematics during prone hip extension does not predict the delayed trunk muscle onset in patients with CLBP.