Flexion Relaxation and Its Relation to Pain and Function over the Duration of a Back Pain Episode

BACKGROUND: Relaxation 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 RESULTS: 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. 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. CONCLUSIONS: The 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

The impact of aerobic fitness on functioning in chronic back pain

Despite lack of convincing evidence that reduced aerobic fitness is associated with chronic back pain (CBP), exercise programs are regarded as being effective for persons with non-specific CBP. It is unsure whether gain in aerobic fitness following intervention is associated with functioning improvement in persons with CBP. The objective of this prospective cohort study was to study the impact of aerobic fitness on functioning in persons with CBP, at baseline and following 3-week intensive interdisciplinary intervention. This study included persons who had passed 8 weeks of sick-listing because of back pain (n = 94) and were referred to a 3-week intensive biopsychosocial rehabilitation program. Aerobic fitness was assessed with a sub-maximal bicycle test at baseline, at admission to and discharge from the rehabilitation program, and at 6 months follow-up. Contextual factors, body function, activity and participation were evaluated before and after intervention. In addition, working ability was recorded at 3-years follow-up. At baseline aerobic fitness was reduced in most subjects, but improved significantly following intervention. Baseline measurements and intervention effects did not differ among the diagnostic sub-groups. Neither contextual factors nor functioning at baseline were associated with aerobic fitness. Increase in aerobic fitness was not associated with improvements in functioning and contextual factors and work-return following intervention either. From this study we conclude that improvement of aerobic fitness seems of limited value as goal of treatment outcome for patients with CBP