Evaluation of muscle fatigue based on surface electromyography and subjective assessment

In this paper, an assessment model for muscle fatigue was constructed with mean fatigue energy and subjective feeling of fatigue degree for the entire process of the experiment. The model which combined objective and subject data will be valuable for improving work efficiency and for monitoring muscle fatigue. To investigate the relationship between surface electromyography and subjective assessment of muscle fatigue, twenty young male volunteers participated in the experiment of pistol holding and aiming. sEMG of the anterior deltoid was recorded during the entire process, while fatigue assessments (Borg scale) were collected every 30s. We divided the signal into several parts and then octave band method was used to calculate mean energy of each part. An equation was derived based on the relationship between the mean energy of sEMG and Borg scale. The results demonstrated that a quadratic curve reflected the relationship between fatigue energy and fatigue sensation, which suggests that fatigue energy can be calculated to use to collect sEMG activity recordings, and that fatigue sensation can be determined using this evaluation model. This model therefore provides a suitable basis for developing fatigue-monitoring equipment based on sEMG activity, as well as providing a theoretical and design basis for monitoring the fatigue levels of operators, and designing and planning jobs to make them more ergonomic and intuitive.