Effects of Low Back Pain on Back Muscle Coordination: a Surface EMG Study

Abstract

Among different pathologic conditions that give rise to Low Back Pain (LBP), abnormal back muscle contraction strategy was suspected to be a major contributory factor. However, studies in this area are few. The purposes of this study were to establish a reliable and objective assessment method which provides information on back muscles coordination during dynamic motion, and to testify the possible application of this method in LBP rehabilitation assessment. Back muscle surface electromyography (SEMG) was measured by an array of SEMG electrodes (7x3) during forward bending. The root mean square (RMS) of the SEMG signal was calculated as a function of both position and time to produce the SEMG topography. The SEMG topography of 20 healthy subjects served as the normal database and produced a reproducible activation pattern. SEMG topography of the 15 LBP patients presented varied activation pattern and were different from that of normal pattern. Corrective changes of contraction strategies revealed in SEMG topography patterns were found in some of the LBP patients after rehabilitation. In this study, the effectiveness of LBP rehabilitation was uncovered by SEMG topography, with a visible monitoring of rehabilitation progress. With this method, a practical and objective assessment for LBP rehabilitation is achievable.