Muscle Activation Changes After Exercise Rehabilitation for Chronic Low Back Pain

Marshall PW, Murphy BA. Muscle activation changes after exercise rehabilitation for chronic low back pain.

Objective

To investigate the changes in 2 electromyographic measures, flexion relaxation (FR) response and feed-forward activation of the deep abdominals, associated with low back pain (LBP) after different rehabilitation interventions.

Design

A 2×2 factorial design with subjects' self-selecting treatment with randomization after 4 weeks to either the specific exercise group or exercise advice group for a further 12-week period.

Setting

General community practitioners and university training center.

Participants

Subjects with chronic nonspecific LBP were recruited for this study. A total of 112 people were initially screened, and 60 were recruited for the study, with 50 being available for long-term follow-up.

Intervention

Four weeks of treatment (manipulative or nonmanipulation) and 12 weeks of subsequent exercise (supervised Swiss ball training or exercise advice).

Main Outcome Measures

The Oswestry Disability Index, FR response measured at T12-L1 and L4-5, and feed-forward activation of the deep abdominal muscles.

Results

More rapid improvements in disability were identified for subjects who received the supervised exercise program. The FR response at L4-5 also increased more for those who received directly supervised exercise. Long-term follow-up showed that there was still a between-group difference in the FR response, despite no difference in self-rated disability. Long-term changes were observed for the feed-forward activation of the deep abdominals; however, no exercise or treatment effects were identified.

Conclusions

Supervised exercise rehabilitation leads to more rapid improvements in self-rated disability, which were associated with greater improvement in the low back FR response.