Individuals with non-specific low back pain use a trunk stiffening strategy to maintain upright posture

Department of Rehabilitation and Movement Science, University of Vermont, Burlington, VT, USA.
Journal of electromyography and kinesiology: official journal of the International Society of Electrophysiological Kinesiology (Impact Factor: 1.65). 11/2011; 22(1):13-20. DOI: 10.1016/j.jelekin.2011.10.006
Source: PubMed


There is increasing evidence that individuals with non-specific low back pain (LBP) have altered movement coordination. However, the relationship of this neuromotor impairment to recurrent pain episodes is unknown. To assess coordination while minimizing the confounding influences of pain we characterized automatic postural responses to multi-directional support surface translations in individuals with a history of LBP who were not in an active episode of their pain. Twenty subjects with and 21 subjects without non-specific LBP stood on a platform that was translated unexpectedly in 12 directions. Net joint torques of the ankles, knees, hips, and trunk in the frontal and sagittal planes as well as surface electromyographs of 12 lower leg and trunk muscles were compared across perturbation directions to determine if individuals with LBP responded using a trunk stiffening strategy. Individuals with LBP demonstrated reduced peak trunk torques, and enhanced activation of the trunk and ankle muscle responses following perturbations. These results suggest that individuals with LBP use a strategy of trunk stiffening achieved through co-activation of trunk musculature, aided by enhanced distal responses, to respond to unexpected support surface perturbations. Notably, these neuromotor alterations persisted between active pain periods and could represent either movement patterns that have developed in response to pain or could reflect underlying impairments that may contribute to recurrent episodes of LBP.

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Available from: Sharon Henry, Oct 28, 2015
    • "Integrated EMG amplitudes of each epoch were analyzed separately due to their unique functional implications. Responses to lateral (combined left and right), forward, and backward perturbations were also analyzed separately because LBP, and treatment for LBP, may differentially affect responses across these conditions based on different mechanical constraints (Jacobs et al., 2011; Jones et al., 2012a,b). Neural mechanisms controlling individual abdominal and oblique muscles are also task-specific to different directions of surface translations (Carpenter et al., 2008). "
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