Comparison of the effects of stability exercise and balance exercise on muscle activity in female patients with chronic low back pain.

Stability exercise (SE) and balance exercise (BE) are generally-applied clinical interventions for back pain. For a proper clinical application, it is necessary to characterize and compare the effects of SE and BE on low back pain (LBP). The purpose of this study was to compare the effects of SE and BE on the activity of trunk muscles in women with chronic LBP. Women with chronic LBP (n=30) who volunteered for this study were randomly divided into two exercise groups of 15 participants. We obtained pre- and postintervention data through application of the visual analogue scale (VAS), Oswestry Disability Index (ODI), and electromyography (EMG). While post-intervention EMG showed decreased activity of the external oblique (EO) in the SE group, the EMG results in the BE group showed increased EO activity (<0.05). Both groups had increased muscle activity of the erector spinae (<0.05). Both groups showed significant reductions on the VAS and ODI (<0.05). Both SE and BE were effective in reducing pain in the study participants. The decrease in EO muscle activity in the SE group seems to be due to the SE inducing cocontraction and distributing the role of the EO to other muscles. In contrast, EO muscle activity was increased in the BE group. It appears that the EO is important in maintaining the center of gravity and base of support during BE. The role of EO seems to maintain trunk stability as it increases muscle activity of EO.