Aim: To determine the significant difference in lumbar multifidus activity within the patient with unilateral chronic low back pain and its association with lumbar range of motion.

Study design: Analytical cross-sectional study

Study setting and duration: Former institute of Dow University of Health Sciences, Karachi, Pakistan (Institute of Physical Medicine and Rehabilitation) which has become Sindh Institute of Physical Medicine and Rehabilitation and study duration was March 2020 to December 2020.

Methodology: About 128 patients with unilateral chronic low back pain were assessed for the lumbar multifidus activity based on the percentage of maximum voluntary contraction through surface electromyography. Lumbar flexion and extension range of motion was measured through Modified-Modified Schober’s test. All the data were analyzed through the Statistical Package of Social Sciences 21. Nonparametric tests were employed. The level of significance was 0.05.

Results: The lumbar multifidus activity was significantly increased (p<0.001) on the painful side than the non-painful side. However, there was a significant negative correlation (rh=- 0.551, -0.703; p<0.001) of only painful side lumbar multifidus activity with flexion and extension range of motion.

Conclusion: Activity of painful side lumbar multifidus increases in unilateral chronic low back pain. Furthermore, it increases with a decrease in lumbar flexion and extension range of motion. 

Keywords: Correlation Study, disability, Low Backaches, non-specific low back pain, Surface Electromyography