Functional Electrical Stimulation (FES) plays a crucial role in the rehabilitation and mobility of patients, but it introduces muscle fatigue, which can impact the treatment process. This work presents a novel approach for monitoring FES-induced muscle fatigue and recovery by torque and surface electromyography (sEMG) signals. A predefined pattern of FES is applied on the rectus femoris muscle to induce isometric contraction, while torque and sEMG data are collected to assess muscle fatigue and subsequent recovery. The sEMG data are filtered using notch stop and high-pass filters, and subsequently assessed in both the time domain (Root Mean Square, RMS) and frequency domain (mean frequency). The results indicated that torque and RMS decrease during fatigue and increase during recovery, while the mean frequency of the sEMG signal exhibited an opposite trend. These findings provide valuable insights into the dynamics of muscle fatigue under FES and have implications for enhancing the understanding and management of muscle fatigue in rehabilitation therapy.
