Abstract
BackgroundRelaxation of the erector spinae often occurs in healthy individuals as full trunk flexion is achieved when bending forward from standing. This phenomenon, referred to as flexion relaxation is often absent or disrupted (EMG activity persists) in individuals reporting low back pain (LBP).Methods and ResultsSelf-reported pain and disability scores were compared to EMG measures related to the flexion relaxation (FR) phenomenon by 33 participants with LBP at up to eight sessions over a study period of up to eight weeks. Fourteen participants served as a control group. In the protocol, starting from standing participants bent forward to a fully flexed posture, and then extended the trunk to return to standing position. A thoracic inclinometer was used to measure trunk posture. Surface electrodes located at the L2 and L5 levels recorded EMG amplitudes of the erector spinae. Ratios of EMG amplitudes recorded during forward bending to amplitudes at full flexion, and ratios of extension to full flexion were calculated. EMG amplitudes and their ratios were compared between control and LBP groups at the initial visit. No significant differences between groups were found except at the L5 location at full flexion. Correlations of the ratios to pain and function scores recorded in repeated sessions over the LBP episode also were compared between LBP group participants classified as having transient, recurrent or chronic symptoms. In another analysis participants were grouped by whether their symptoms resolved over the study period.ConclusionsThe transient LBP group had significantly stronger correlations between pain and function to both ratios, than did those with more chronic LBP symptoms. Participants who experienced symptom resolution generally had stronger correlations of ratios to both pain and function than those with partial or no resolution. Improved understanding of these relationships may provide insight in clinical management of LBP.
Highlights
The observation of electrical silence of the erector spinae (ES) at full trunk flexion was first referred to as flexion relaxation (FR) by Floyd and Silver [1]
Adams et al suggested that when the ES is electrically silent at full trunk flexion, passive tension of the muscle tissue could provide some resistance to trunk moment [4]
The literature suggests that FR of the lumbar ES at full trunk flexion is observed in the majority of healthy individuals without back pain, though substantial variability in the behavior exists, likely due to individual differences such as anthropometric variation as well as differences in protocols [1,5,6,7,8,9,10]
Summary
Self-reported pain and disability scores were compared to EMG measures related to the flexion relaxation (FR) phenomenon by 33 participants with LBP at up to eight sessions over a study period of up to eight weeks. EMG amplitudes and their ratios were compared between control and LBP groups at the initial visit. Correlations of the ratios to pain and function scores recorded in repeated sessions over the LBP episode were compared between LBP group participants classified as having transient, recurrent or chronic symptoms. In another analysis participants were grouped by whether their symptoms resolved over the study period
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
