New Index for Muscle Fatigue Quantification in Sustained Static Contraction Using Surface Electromyogram Signal

Fatigue is a subjective concept and its definition is very complex, not unique and controversial. The detection and classification of muscle fatigue, provides useful information in many research areas. During a sustained voluntary contraction, even when there is no voluntary change of muscle state, the electromyogram signal can be considered to be non-stationary simply due to the inherent physiology of the organ. Spectral analysis of electromyogram signals has been widely used to estimate localized muscular fatigue. The most commonly used frequency variables in electromyogram studies are mean and median frequency, which are not compatible with non-stationary nature of electromyogram signals. This study, for the first time, employed empirical mode decomposition analysis as a new index for the quantification of muscle fatigue in sustained static contraction using surface electromyogram. The results of this study well- presented that slope of regression line on median frequency is not robust to the variations of frame lengths. In contrast, being based on the local characteristic time scale of the data, empirical mode decomposition is applicable to nonlinear and non-stationary processes. Additionally, being adaptive, this decomposition method is highly efficient.

کلیدواژه ها:

muscle fatigue ، electromyogram ، median frequency ، empirical mode decomposition