Effect of Core Stability Exercises on Feedforward Activation of Deep Abdominal Muscles in Chronic Low Back Pain: A Randomized Controlled Trial.

Author(s): Vasseljen O, Unsgaard-Tondel M, Westad C, Mork PJ

Affiliation(s): Department of Public Health and General Practice, Faculty of Medicine, Norwegian University of Science and Technology, P.b. 8905, MTFS, 7491 Trondheim, NORWAY. Department of Public Health and General Practice, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway Department of Human Movement Science, Faculty of Social Science and Technology Management, Norwegian University of Science and Technology Trondheim, Norway Department of Human Movement Science, Faculty of Social Science and Technology Management, Norwegian University of Science and Technology, Trondheim, Norway.

Publication date & source: 2011-12-03, Spine (Phila Pa 1976)., [Epub ahead of print]

ABSTRACT: Study Design. Randomized controlled trial.Objective. To investigate feedforward activation or timing of abdominal muscle activation in response to rapid shoulder flexion after 8 weeks with core stability exercises, sling exercises, or general exercises in patients with chronic nonspecific low back pain (LBP).Summary of Background Data. Delayed onset in abdominal muscles has been associated with LBP. Low load exercises to volitionally activate the transversus abdominis were introduced to restore trunk muscle activation deficits. More forceful co-contraction exercises have been advocated by others. This study explored if abdominal muscle onset changed after low load core stability exercises, high load sling exercises, or general exercises.Methods. Subjects (N = 109) with chronic nonspecific LBP of at least three months duration were randomly assigned to 8 weekly treatments with low load core stability exercises, high load stabilizing exercises in slings, or general exercises in groups. Primary outcome was onset recorded bilaterally by m-mode ultrasound imaging in the deep abdominal muscles in response to rapid shoulder flexion.Results. No or small changes were found in onset after treatment. Baseline-adjusted between group differences showed a 15 ms (95% CI, 1-28, P = 0.03) and a 19 ms (95% CI, 5-33, P<0.01) improvement with sling relative to core stability and general exercises, respectively, but on one side only. There was no association between changes in pain and onset over the intervention period (R</=0.02).Conclusion. Abdominal muscle onset was largely unaffected by 8 weeks of exercises in patients with chronic LBP. There was no association between change in onset and LBP. Large individual variations in activation pattern of the deep abdominal muscles may justify exploration of differential effects in subgroups of LBP.