Altered Multifidus Recruitment During Walking in Young Asymptomatic Individuals With a History of Low Back Pain

Study Design Controlled laboratory study, with a case-control, cross-sectional design. Background Individuals with low back pain have impaired activation of the multifidus during postural adjustments and increased activity of the erector spinae musculature during walking. However, it is unclear whether these alterations in muscle activity are evident during locomotion in individuals with a history of low back pain when they are between symptomatic episodes. Objectives To compare paraspinal muscle activity in young, healthy individuals and young individuals with a history of low back pain during walking turns. Methods Fourteen asymptomatic individuals with a history of low back pain and 14 controls performed 90° walking turns at both a self-selected speed and a fast speed. The duration and amplitude of activity in the deep fibers of the multifidus and the lumbar and thoracic longissimus were quantified using intramuscular electromyography. Results There was a significant speed-by-group interaction for the duration of multifidus activity (P = .013). Duration of activity increased from the self-selected speed to the fast locomotor speed in the controls, but decreased in the individuals with a history of low back pain (P = .003). Self-selected speed was the same in both groups (P = .719). There was a trend toward a significant association between group and the direction of change in the duration of deep multifidus activity (χ(2) = 0.058). Duration of thoracic longissimus activity and amplitude of multifidus and thoracic longissimus activity increased similarly in both groups from the self-selected to the faster speed. Conclusion Even between symptomatic episodes, young individuals with a history of low back pain demonstrated altered recruitment of the deep fibers of the lumbar multifidus in response to changing locomotor speed during walking turns. J Orthop Sports Phys Ther 2016;46(5):365-374. Epub 21 Mar 2016. doi:10.2519/jospt.2016.6230.