AB1197 Changes in Lumbar Spinopelvic Pattern of Movement Influence the Flexion Relaxation of the Erector Spinae
Authors: M. Sarti, M.D. Ybáñez-García, R. Expositor-Rodríguez, C. Barrios
Journal: Annals of the Rheumatic Diseases (2015)

<h3>Background</h3> In healthy subjects, the erector spinae muscles (ES) exhibits a relaxation of its electrical activity when the trunk is nearby its full flexion. <h3>Objectives</h3> To find out the influence of exhibiting a lumbar spine or a pelvis dominant pattern of movement during trunk flexion from upright position on the appearance of the myoelectric relaxation of the erector spinae. In healthy subjects, the erector spinae muscles (ES) exhibits a relaxation of its electrical activity when the trunk is nearby its full flexion. <h3>Objectives</h3> To find out the influence of exhibiting a lumbar spine or a pelvis dominant pattern of movement during trunk flexion from upright position on the appearance of the myoelectric relaxation of the erector spinae. <h3>Methods</h3> EMG from the right ES muscles was recorded during standardized trunk flexion movement from the upright position. Disposable surface electrodes Ag-AgCl were applied bilaterally to the skin 3 cm lateral from the spinous process at the L3 level. The EMG signal was full-wave rectified and averaged (40ms) to produce a linear envelope. An electrogoniometer measured the differential lumbar spine - pelvis sagittal angular displacement during trunk flexion in asymptomatic females. Both signals (EMG and degrees) were synchronously captured and feed into the same PC. Ranges of the lumbar spine, pelvis and trunk motion (lumbar spine + pelvis) were calculated for the entire movement. According to exhibiting a pelvis or lumbar spine dominant pattern of movement the subjects were assigned respectively to group1 (n=9) and group2 (n=13) (mean ± SD age, 21.6±2.2 and 22.2±2.0 years, respectively). The myoelectric relaxation appearance. was defined as the electrical activity of the ES that was less than that in erect standing (basal EMG), then the degrees of trunk, pelvis, and spine flexion were determined at this point for both groups and were further normalized to the maximum range of trunk, pelvis and spine flexion. One-way MANOVA was calculated to determine differences in the referred to ranges of flexion at the appearance of the myoelectric relaxation between groups. <h3>Results</h3> The myoelectric relaxation of the ES appeared at significantly greater relative range of spine flexion in group 1 than 2 [group1: 90%±8% (43.9°±8.5°), group2: 83%±6 (59.3°±11.1°)]. There were not significant differences in the relative range of trunk flexion (group1: 58%±12% (73.2°±22.9°), group2: 58.5%±12.2% (69.6±17.2). ES relaxation appears at a greater relative degree lumbar flexion in group 1 than in 2. In group 2 females exhibited a greater range of movement with no electrical activity until the full flexion was reached. Therefore, structures of the spine support the flexion moment without the protection of the muscle activity. <h3>Conclusions</h3> The appearance of the myoelectric relaxation of the erector spinae is influenced by the variance in lumbar spinopelvic pattern of movement. <h3>References</h3> Response of the flexion-relaxation phenomenon relative to the lumbar motion to load and speed. Sarti MA, Lisόn JF, Monfort M, Fuster MA. Spine 26 2001; E421-E426. <h3>Acknowledgements</h3> This investigation has been supproted by the following grants: Ref. FIS2001-0070-01, Ref. TIC 2001-2786-C02-02, Ref. AP2001-376. <h3>Disclosure of Interest</h3> None declared