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Updated: Aug 13, 2026

Ex Vivo Assessment of Contractility, Fatigability and Alternans in Isolated Skeletal Muscles
Published on: November 1, 2012
Mechanomyographic and electromyographic responses to eccentric muscle contractions
Jared W Coburn1, Terry J Housh, Moh H Malek
1Department of Kinesiology, California State University, Fullerton, 800 N. State College Blvd., KHS-235, Fullerton, California 92834-6870, USA. jcoburn@fullerton.edu
Abstract:
Little is known regarding the modulation of torque during eccentric muscle actions. Mechanomyographic (MMG) and electromyographic (EMG) signals have been used to examine motor control strategies. The purpose of this study was to examine the MMG and EMG amplitude and frequency in relation to torque during eccentric muscle contractions. Eight women performed eccentric leg extension muscle contractions at 10-100% of peak torque (PT). A piezoelectric crystal contact sensor and bipolar surface electrodes were placed on the vastus medialis to detect the MMG and EMG signals. Polynomial regression analyses indicated that EMG amplitude (r(2)=0.994) and MMG wavelet center frequency (CF) (r(2)=0.846) increased linearly to 100% eccentric PT, whereas there were no significant relationships for EMG wavelet CF or MMG amplitude and eccentric torque. These results suggested that eccentric torque is primarily modulated through changes in motor unit firing rate.
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