TY - JOUR
T1 - EMG as an Indicator of Fatigue in Isometrically Fes-Activated Paralyzed Muscles
AU - Mizrahi, J.
AU - Levy, M.
AU - Ring, H.
AU - Isakov, E.
AU - Liberson, A.
N1 - Funding Information:
Manuscript received March 17, 1993; revised June 22, 1994. This work was supported by the Segal Foundation and by the Walter and Sandra Kaye Research Fund. J. Mizrahi and M. Levy are with the Julius Silver Institute of Biomedical Engineering Sciences and Department of Biomedical Engineering, Technion-IIT, Haifa 32000, Israel. H. Ring and E. Isakov are with the Bnai Zion Medical Center, Haifa, Israel. A. Lieberson is with the Loewenstein Rehabilitaion Center, Raanana, Israel. IEEE Log Number 94041 15.
PY - 1994/6
Y1 - 1994/6
N2 - The lower limb of a paraplegic patient can be analyzed as a dynamically determinate system, since the muscles there are isolated from voluntary control. Hence, when activated by functional electrical stimulation (FES), the only nonzero active muscle forces are those of the actually stimulated muscles. This unique situation allows the calculation of the muscle force from the externally measured torques and the correlation of this direct muscle output to parameters of another nature, such as metabolic or myoelectric. In the present work we have studied the relation between force and myoelectric activity of the FES-activated quadriceps muscles of paraplegics during the course of fatigue. Stimulation was provided by means of surface electrodes. The electromyographic (surface EMG) activity was represented by the peak-to-peak (PTP) amplitude of the M-wave signal obtained. It was important to suppress the stimulus artifact preceding the EMG signal and we, therefore, designed an amplifier capable of monitoring the artifact-free signal. The surface EMG and the force were sampled on line for analysis. The PTP amplitudes were correlated with the corresponding force values, simultaneously measured and a parallel decay in these two parameters was noticed. An exponential curve was found adequate to express the relationship between force and EMG PTP. The results obtained indicate the conditions under which surface EMG can be used to noninvasively monitor the quadriceps muscle fatigue during stimulation.
AB - The lower limb of a paraplegic patient can be analyzed as a dynamically determinate system, since the muscles there are isolated from voluntary control. Hence, when activated by functional electrical stimulation (FES), the only nonzero active muscle forces are those of the actually stimulated muscles. This unique situation allows the calculation of the muscle force from the externally measured torques and the correlation of this direct muscle output to parameters of another nature, such as metabolic or myoelectric. In the present work we have studied the relation between force and myoelectric activity of the FES-activated quadriceps muscles of paraplegics during the course of fatigue. Stimulation was provided by means of surface electrodes. The electromyographic (surface EMG) activity was represented by the peak-to-peak (PTP) amplitude of the M-wave signal obtained. It was important to suppress the stimulus artifact preceding the EMG signal and we, therefore, designed an amplifier capable of monitoring the artifact-free signal. The surface EMG and the force were sampled on line for analysis. The PTP amplitudes were correlated with the corresponding force values, simultaneously measured and a parallel decay in these two parameters was noticed. An exponential curve was found adequate to express the relationship between force and EMG PTP. The results obtained indicate the conditions under which surface EMG can be used to noninvasively monitor the quadriceps muscle fatigue during stimulation.
UR - http://www.scopus.com/inward/record.url?scp=0028443311&partnerID=8YFLogxK
U2 - 10.1109/86.313147
DO - 10.1109/86.313147
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AN - SCOPUS:0028443311
SN - 1063-6528
VL - 2
SP - 57
EP - 65
JO - IEEE Transactions on Rehabilitation Engineering
JF - IEEE Transactions on Rehabilitation Engineering
IS - 2
ER -