A power spectral study of surface EMG of muscles subjected to non-repetitive task

For a proper understanding and interpretation of the changes in the power spectral characteristics of surface EMG from any fatigued muscle of a worker employed on repetitive assembly line tasks, it is important to study first the changes in the spectral characteristic of the surface EMG of the same muscle of the worker assigned with non-repetitive tasks. The information obtained from the EMG study with non-repetitive tasks would serve as a control to identify and evaluate the changes in the power spectral features of the surface EMG of the muscle due to, in particular, the repetitive nature of the task under similar work environment. In this study the EMG signals from thenar fascia and biceps of two healthy workers engaged in non-repetitive tasks in an electronic industry have been recorded in the morning (before the start of the work) and again the evening (after the completion of day's work). The frequency wise distribution of the number of peaks (NP) and the power content (PC) of the signal have been evaluated within the range of 60-200 Hz. It is found that there is no significant difference in the frequency wise distribution of NP and PC in the power spectrum of the EMG signals recorded in the morning and evening.