Interventions focusing on trunk muscle impairments in people with LBP have been promoted; however, the treatment effects on muscle activation impairments during postural tasks remain unclear. Therefor the objective of this study was to evaluate the effects trunk stabilization vs. general strength and conditioning exercises on the automatic postural response in persons with chronic low back pain (LBP). Fifty-eight subjects with chronic, recurrent LBP (n=58) (i.e., longer than six months) were recruited and place at random in to one of two, 10-week physical therapy programs: stabilization (n=29) or strength and conditioning (n=29). Pain and function were measured at 11 weeks and 6 months after treatment initiation. To quantify postural following support surface perturbations, surface electrodes recorded electromyography (EMG) of trunk and leg muscles and force plates recorded forces under the feet, to calculate the center of pressure. Both groups exhibited significant improvements in pain and function out to 6 months. There were also changes in muscle activation patterns immediately after treatment, but not at 6 months. However, changes in center of pressure (COP) responses were treatment specific. After treatment, the stabilization group demonstrated later onset of COP displacement, while the onset of COP displacement in the strengthening group was significantly earlier following treatment.
Despite two different treatments, clinical improvements and muscle activation patterns were similar for both groups, suggesting that the stabilization treatment protocol does not preferentially improve treatment outcomes or inter-muscle postural coordination patterns for individuals with LBP.