Lumbar Multifidus Muscle Thickness Does Not Predict Patients With Low Back Pain Who Improve With Trunk Stabilization Exercises

ObjectiveTo understand lumbar multifidus (LM) muscle activation as a clinical feature to predict patients with low back pain (LBP) who are likely to benefit from stabilization (STB) exercises.DesignProspective, cohort study.SettingOutpatient physical therapy clinics.ParticipantsPersons with LBP were recruited for this study. Subjects (N=25) were classified as either eligible to receive STB exercises or ineligible on the basis of current clinical prediction rules.InterventionsSix weeks of STB treatment.Main Outcome MeasuresBefore and after treatment, subjects underwent rehabilitative ultrasound imaging to quantify LM-muscle activation and completed disability and pain questionnaires. Analyses were performed to examine the (1) relation between LM-muscle activation and current clinical features used to predict patients with LBP likely to benefit from STB exercises, (2) LM-muscle activation between the STB-eligible and STB-ineligible groups before and after STB treatment, and (3) relation between LM-muscle activation before STB treatment and (a) disability and (b) pain outcomes after treatment for both groups.ResultsNo relation was found between LM-muscle activation and the number of clinical features. Before STB treatment, LM-muscle activation between the STB-eligible and STB-ineligible groups did not differ. After STB treatment, LM-muscle activation differed between the groups; however, this interaction was because the LM-muscle activation for the STB-eligible group decreased after treatment while that for the STB-ineligible group increased after treatment. Finally, only the STB-eligible group had a significant reduction in disability following treatment; however, no relation was found between LM-muscle activation before treatment and (a) disability or (b) pain outcomes after treatment in the STB-eligible group.ConclusionsLM-muscle activation does not appear to be a clinical feature that predicts patients with LBP likely to benefit from STB exercises.