Functional Electrical Stimulation (FES) is the application of electrical current towards functional movements. FES is widely utilised in fields such as post-stroke rehabilitation. However, the application of FES is hindered by patient fatigue which limits rehabilitation time. The study of FES elicited fatigue is essential for optimising the modality’s therapeutic impact. Electromyography (EMG) is a useful tool for assessing stimulation induced contractions. Current studies typically assess EMG under restricted conditions such as isometric contractions and constant stimulation. Practical FES is not often delivered this way. In this study, the reliability of evoked EMG&nbsp;median frequency (MDF) and peak-to-peak (PTP) fatigue indices were investigated during dynamic stimulation of the forearm. During isometric constant stimulation the MDF-time and PTP-time waveforms exhibited negative gradients in the ranges (-1.3 to -3.6) Hz.s-1&nbsp;and (-0.013 to -0.016) V.s-1&nbsp;respectively, most with coefficients of determination (R2) greater than 0.83. During vEMG-controlled stimulation the MDF-contraction waveforms exhibited negative gradients in the range (-2.4 to -9.0) Hz.Cont-1 while the PTP gradients ranged from (0.0070 to -0.019) V.Cont-1. For these datasets the MDF waveforms’ R2 &gt; 0.62 and most PTP waveforms’ R2 &lt; 0.35. These findings suggest that the MDF and PTP amplitude are suitable fatigue indices during isometric constant stimulation but the PTP-based index becomes unreliable during vEMG-controlled stimulation.

Evoked Electromyographic Fatigue Indices During Intermittent Stimulation Towards Dynamic Wrist Contractions

Paper Proceedings: https://asmedigitalcollection.asme.org/IDETC-CIE/IDETC-CIE2021/volume/85369

ASME 2021 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference (IDETC/CIE2021)

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