Using EMG to evaluate muscular fatigue induced during video display terminal keyboard use task

Work-related muscular fatigue is a common problem among office computer users. The purpose of this study was to examine shoulder and arm muscular fatigue induced during visual display terminal (VDT) keyboard use tasks. Electromyography signals were recorded from the right side upper trapezius, deltoid and extensors of the wrist/fingers during VDT task and during isometric contractions task respectively. Mean Power Frequency (MPF) and Root Mean Square value (RMS) were computed and used to evaluate the changes of EMG signal of all measured muscles. The results showed that MPF decrease and RMS increase with time during every isometric contraction experimental blocks for all measured muscles. However, RMS and MPF did not showed obvious trend with time throughout VDT experimental task and throughout isometric contraction experimental task, it is means that MPF and RMS obtained during isometric contraction are not sensitive parameters of muscle fatigue. These results are helpful for finding effective objective assessment method that can identify office VDT workers who are at risk to develop chronic neck, shoulder and arm complaints.