Realization of lumbar muscle activities using quantitative surface electromyographic topography

Lumbar muscle activity assessment was useful in evaluating the muscle conditions of low back pain (LBP) patients. Among many assessment methods, surface electromyography (surface EMG) offered a non-invasive and objective alternative for muscle function studies. However there is no benchmark method for interpreting pathological significance of surface EMG. Surface EMG topography is a novel technique in visualizing and presenting myoelectric activities in lumbar muscle upon static and dynamic motions. Previous studies attempted to uncover the usefulness of topographic features, though quantitative analyses were few. The objective of this study was to realize the significance of topographic features with use of quantitative methods. Ten healthy male subjects were recruited for a control database for surface EMG topographic features. Surface EMG was recorded from the subjects in lumbar region during forward bending by an electrode array. Root mean square (RMS) values of myoelectric signals were calculated to construct topography representing lumbar myoelectric activities. Relative area (RA), relative width (RW), relative height (RH) and Width-to-Height Ratio (W/H) were chosen as the four quantitative parameters in measuring topographic features. The control data was compared against a LBP patient group of eight subjects to investigate the deviation in the four topographic parameters. RW and W/H in patient group were found significantly larger than normal group. The result of this study suggested a quantitative and objective approach in investigating lumbar myoelectric activities to realize LBP disorder and implied evaluation assessment for LBP rehabilitation.