Flexion relaxation phenomenon of back muscles in discriminating between healthy and chronic low back pain women

Abstract

This paper describes the investigation of Surface Electromyography (sEMG) signals of back muscles during forward flexion and extension in healthy and low back pain (LBP) women. Flexion Relaxation Phenomenon (FRP) of EMG was observed and quantitatively analyzed. There were three groups of Malaysian women aged between 20 to 50 years old volunteers participated in this study. The groups were group 1, 2, and 3 which consist of 5 healthy women, 5 LBP patients with FRP and 5 LBP patients without FRP with respectively. Every participant was trained to perform two types of forward flexion; maximum forward flexion and 90° forward flexion with hands on the knees. The sEMG and the motion signals were recorded during forward flexion of the trunk at the back muscles. Four parameters were found to be statistically significant differences (p<0.001) amongst groups. These parameters are average RMS during full flexion, ratio between average RMS during full flexion and average RMS during standing, flexion relaxation ratio (FRR) and extension relaxation ratio (ERR). © 2008 Springer-Verlag.