Recovery of the Lumbar Multifidus Muscle Size in Chronic Low Back Pain Patients by Strengthening Hip Abductors: A Randomized Clinical Trial

Abstract Introduction Decrease in cross-sectional thickness of lumbar multifidus (MF) muscles during prolonged low back pain episodes commonly occurs. Restoration of the MF muscle size can be an effective way of treating chronic low back pain (CLBP) patients. Traditionally, clinicians apply muscle stabilization exercises for these patients. Recent studies support the need for active strengthening exercises for treatment of the CLBP patients. Objective The MF muscles provide lumbar stability, and therefore we hypothesized that strengthening of these muscles can be more effective than the MF muscle stabilization exercises in restoration of the muscle size. Design Study design was a randomized allocation control trial with two groups of adult female CLBP patients (n = 12 each; age range of 20-45). Patients in the control group underwent stabilization exercises and the patients in the intervention group underwent the hip abductor strengthening exercises. Setting For all subjects of each group, the trials continued in 24 sessions distributed over 8 weeks and the MF muscles were measured in the beginning of the first session and one week after completion of the last session. Main Outcome Measures Statistical significance (p-value) of the change in the average MF muscle thickness, pain, and disability scores along with for each group were estimated. Results Both regimens of exercises can significantly decrease the pain and disability: average pain and disability reductions of 46% (p-value of 0.001) and 33% (p-value of 0.02) via stabilization versus average pain and disability reductions of 65% (p-value of 0.001) and 59% (p-value of 0.001) via hip abductor strengthening. However, the hip abductor strengthening is the sole statistically significant exercise regimen (p-value of 0.014 vs 0.94) for increasing the MF muscle size. Conclusion Replacement of the traditional stabilization exercises with the hip abductor strengthening exercises for effective treatment of female adults with CLBP is recommended.