Surface EMG as a fatigue indicator during FES-induced isometric muscle contractions

Naomi C. Chester; William K. Durfee

doi:10.1016/S1050-6411(96)00016-8

Surface EMG as a fatigue indicator during FES-induced isometric muscle contractions

Naomi C. Chester, William K. Durfee

Mechanical Engineering

Research output: Contribution to journal › Article › peer-review

60 Scopus citations

Abstract

The electromyogram (EMG) signal has potential as an indicator of stimulated muscle fatigue in applications of functional electrical stimulation (FES). In particular, it could be used to detect near lower limb collapse due to the associated muscle fatigue in FES-aided standing systems and thereby prevent falling. Surface EMG measurement, however, is hampered by stimulation artifact during FES. Modified surface stimulation and EMG detection equipment were designed and built to minimize this artifact and to permit detection of the electrical signal generated by the muscle during contraction. Artifact reduction techniques included shorting stimulator output leads between stimulus pulses and limiting and blanking slew rate in the EMG processing stage. Isometric fatigue experiments were performed by stimulating the quadriceps muscle of 20 able-bodied (a total of 125 trials) and three spinal cord injured (18 trials) subjects. Fatigue-tracking performance indicators were derived from the root-mean-square (RMS) of the EMG amplitude and from the median frequency (MF) of the EMG power spectral content. The results demonstrate that reliable fatigue tracking indicators for practical FES applications will be difficult to obtain, but that amplitude-based measures in spinal cord injured subjects show promise.

Original language	English (US)
Pages (from-to)	27-37
Number of pages	11
Journal	Journal of Electromyography and Kinesiology
Volume	7
Issue number	1
DOIs	https://doi.org/10.1016/S1050-6411(96)00016-8
State	Published - Mar 1997

Bibliographical note

Funding Information:
AcknowledgementsT: his work was supportedb y grants from the General Electric Foundation, the Johnson and Johnson Foundationa nd the National ScienceF oundation. Experimentsw ere performedi n the Newman Laboratory for Biomechanicsa nd Human Rehabilitationa t M.I.T. and at the VA Medical Center, West Roxbury, MA. The authorsw ish to thankC arrie Perlman,a n M.I.T. undergrad-

Copyright:
Copyright 2004 Elsevier Science B.V., Amsterdam. All rights reserved.

Keywords

EMG
FES
Fatigue

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abstract = "The electromyogram (EMG) signal has potential as an indicator of stimulated muscle fatigue in applications of functional electrical stimulation (FES). In particular, it could be used to detect near lower limb collapse due to the associated muscle fatigue in FES-aided standing systems and thereby prevent falling. Surface EMG measurement, however, is hampered by stimulation artifact during FES. Modified surface stimulation and EMG detection equipment were designed and built to minimize this artifact and to permit detection of the electrical signal generated by the muscle during contraction. Artifact reduction techniques included shorting stimulator output leads between stimulus pulses and limiting and blanking slew rate in the EMG processing stage. Isometric fatigue experiments were performed by stimulating the quadriceps muscle of 20 able-bodied (a total of 125 trials) and three spinal cord injured (18 trials) subjects. Fatigue-tracking performance indicators were derived from the root-mean-square (RMS) of the EMG amplitude and from the median frequency (MF) of the EMG power spectral content. The results demonstrate that reliable fatigue tracking indicators for practical FES applications will be difficult to obtain, but that amplitude-based measures in spinal cord injured subjects show promise.",

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N2 - The electromyogram (EMG) signal has potential as an indicator of stimulated muscle fatigue in applications of functional electrical stimulation (FES). In particular, it could be used to detect near lower limb collapse due to the associated muscle fatigue in FES-aided standing systems and thereby prevent falling. Surface EMG measurement, however, is hampered by stimulation artifact during FES. Modified surface stimulation and EMG detection equipment were designed and built to minimize this artifact and to permit detection of the electrical signal generated by the muscle during contraction. Artifact reduction techniques included shorting stimulator output leads between stimulus pulses and limiting and blanking slew rate in the EMG processing stage. Isometric fatigue experiments were performed by stimulating the quadriceps muscle of 20 able-bodied (a total of 125 trials) and three spinal cord injured (18 trials) subjects. Fatigue-tracking performance indicators were derived from the root-mean-square (RMS) of the EMG amplitude and from the median frequency (MF) of the EMG power spectral content. The results demonstrate that reliable fatigue tracking indicators for practical FES applications will be difficult to obtain, but that amplitude-based measures in spinal cord injured subjects show promise.

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Surface EMG as a fatigue indicator during FES-induced isometric muscle contractions

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