LAUSR

An attempt at utilizing mechanomyography (MMG) to quantify muscle fatigue, which occurs on account of repeated functional electrical stimulations (FES), is presented. Twenty-one subjects participated in the experiment, wherein a constant electrical stimulation was repeatedly applied to the tibialis anterior muscle. MMG signals were measured simultaneously, as the stimulations were applied, and subsequently quantified using 8 different methods. Muscle fatigue was confirmed by observing linearly decreasing ankle-joint torque with the repetition of the electrical stimulation (r2 = 0.7823). The convex-hull area and volume along with peak-to-peak MMG signals were found to demonstrate significant linear relationships with muscle fatigue in spite of the weakness in motion artifacts. Use of the Lempel-Ziv algorithm, based on three symbols, provided the most accurate correlations for muscle fatigue. However, frequency-based characteristics as well as mean and median frequencies did not demonstrate any significant linearity with muscle fatigue.