Effects of low back pain stabilization or movement system impairment treatments on voluntary postural adjustments: a randomized controlled trial

Abstract

BackgroundPeople with low back pain (LBP) exhibit impaired anticipatory postural adjustments (APAs). ObjectiveTo evaluate whether current motor retraining treatments address LBP-associated changes in movement coordination during tasks that do and do not require APAs. DesignProspectively registered randomized controlled trial with a blinded assessor. SettingOutcome evaluations occurred in a university laboratory; treatments were carried out in outpatient physical therapy clinics. PatientsFifteen subjects without LBP and 33 subjects with chronic, recurrent, and nonspecific LBP. InterventionTwelve subjects with LBP received stabilization treatment, 21 received movement system impairment–based treatment, for more than 6 weekly 1-hour sessions plus home exercises. MeasurementsPre- and post-treatment, surface electromyography (EMG) was recorded bilaterally from trunk and leg muscles during unsupported and supported leg-lifting tasks, which did and did not require an APA, respectively. Vertical reaction forces under the contralateral leg were recorded to characterize the APA. Oswestry disability scores and numeric pain ratings were also recorded. ResultsPersons with LBP demonstrated an impaired APA compared with persons without LBP, characterized by increased premovement contralateral force application and increased postmovement trunk EMG amplitude, regardless of the task. After treatments, both groups similarly improved in disability and function; however, APA characteristics did not change (ie, force application or EMG amplitude) in either task. LimitationsTreating clinicians were not blinded to treatment allocation, only short-term outcomes were assessed, and main effects of treatment do not rule out nonspecific effects of time or repeated exposure. ConclusionsMovement impairments in persons with LBP are not limited to tasks requiring an APA. Stabilization and movement system impairment–based treatments for LBP do not ameliorate and may exacerbate APA impairments (ie, excessive force application and increased post-movement trunk muscle activation).