Wavelet analysis of electromyography for back muscle fatigue detection during dynamic constant-torque exertions.

The fatigue of the back muscles appears to be strongly implicated as a risk factor for acquisition of low back pain, which is one of the leading ills of our industrial society. Previously, researchers have successfully measured the level of muscular fatigue by using the Fourier transform to analyze the frequency content of the electromyogram (EMG). However, due to the requirement that the EMG signal be stationary, the Fourier transform is suitable only for the analysis of static muscle exertions in which the muscle is held at constant length and tension. Because the majority of industrial work tasks are not static in nature, new methods for quantifying fatigue during dynamic work are needed. The wavelet transform is a novel, although mathematically well developed, technique for analyzing non-stationary signals that has only recently been applied to the study of EMG. Consequently, the main objective of this project is to develop techniques, using the wavelet transform, for the quantification of back muscle fatigue during dynamic repetitive working conditions.