Spatial EMG potential distribution pattern of vastus lateralis muscle during isometric knee extension in young and elderly men |
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Authors: | Kohei WatanabeAuthor Vitae Motoki KouzakiAuthor VitaeRoberto MerlettiAuthor Vitae Mami FujibayashiAuthor Vitae Toshio MoritaniAuthor Vitae |
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Institution: | a Laboratory of Applied Physiology, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan b Japan Society for the Promotion of Science (JSPS), Kyoto, Japan c Laboratory of Neurophysiology, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan d Laboratorio di Ingegneria del Sistema Neuromuscolare, Dipartimento di Elettronica, Politecnico di Torino, Torino, Italy e Division of Physical and Health Education, Setsunan University, Osaka, Japan |
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Abstract: | The aim of the present study was to compare spatial electromyographic (EMG) potential distribution during force production between elderly and young individuals using multi-channel surface EMG (SEMG). Thirteen elderly (72-79 years) and 13 young (21-27 years) healthy male volunteers performed ramp submaximal contraction during isometric knee extension from 0% to 65% of maximal voluntary contraction. During contraction, multi-channel EMG was recorded from the vastus lateralis muscle. To evaluate alteration in heterogeneity and pattern in spatial EMG potential distribution, coefficient of variation (CoV), modified entropy and correlation coefficients with initial torque level were calculated from multi-channel SEMG at 5% force increment. Increase in CoV and decrease in modified entropy of RMS with increase of exerted torque were significantly smaller in elderly group (p < 0.05) and correlation coefficients with initial torque level were significantly higher in elderly group than in young group at moderate torque levels (p < 0.05). These data suggest that the increase of heterogeneity and the change in the activation pattern are smaller in elderly individuals than in young individuals. We speculated that multi-channel SEMG pattern in elderly individual reflects neuromuscular activation strategy regulated predominantly by clustering of similar type of muscle fibers in aged muscle. |
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Keywords: | Aging Multi-channel surface electromyography Knee extensor |
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