Cauchy Wavelet-based Mechanomyographic Analysis for Muscle Contraction Evoked by FES in a Spinal Cord Injured Person

Eddy Krueger, Eduardo M. Scheeren, André E. Lazzaretti, Guilherme N. Nogueira-Neto, Vera L.S.N. Button, and Percy Nohama


Mechanomyography, Cauchy wavelet, functional electrical stimulation, spinal cord injury


The goal of this paper is to evaluate the mechanomyography (MMG) response of rectus femoris muscle based on Cauchy wavelet (CaW) during contraction evoked by functional eletrical stimulation (FES) in a spinal cord injured person. The participant was ranked in American Spinal Injury Association (ASIA) impairment scale as A, i.e. without contraction or sensibility below the lesion level (T3). A triaxial (Z, X and Y axes) MMG sensor was placed over the rectus femoris muscle belly. The CaW was processed in initial and final moments of FES application. The results showed that frequency in (a) initial moment tends to be near the adjusted FES burst frequency (50 Hz), however, in (b) final moment presents compression to frequencies below 18.63 Hz in Z and X axes and in Y axis below 51.12 Hz, therefore, indicating the fibers do not follow the physiological muscular activation mode, as suggested by De Luca and Erim during FES. CaW appears to be suitable to carry out the MMG response during FES application to a spinal cord injured subject making it an important analysis tool because it can show the specific frequency band during neuromuscular physiological changes.

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