HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 92/5/2878    most recent 00367.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (12) Citing Articles via Google Scholar Google Scholar Articles by Zhou, P. Articles by Rymer, W. Z. Search for Related Content PubMed PubMed Citation Articles by Zhou, P. Articles by Rymer, W. Z.

Factors Governing the Form of the Relation Between Muscle Force and the EMG: A Simulation Study

¹Sensory Motor Performance Program, Rehabilitation Institute of Chicago; and ²Biomedical Engineering Department, ³Department of Physiology, and ⁴Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois 60611

Submitted 9 April 2004; accepted in final form 9 June 2004

The dependence of the form of the EMG-force relation on key motoneuron and muscle properties was explored using a simulation approach. Surface EMG signals and isometric forces were simulated using existing motoneuron pool, muscle force, and surface EMG models, based primarily on reported properties of the first dorsal interosseous (FDI) muscle in humans. Our simulation results indicate that the relation between electrical and mechanical properties of the individual motor unit level plays the dominant role in determining the overall EMG amplitude-force relation of the muscle, while the underlying motor unit firing rate strategy appears to be a less important factor. However, different motor unit firing rate strategies result in substantially different relations between counts of the numbers of motoneuron discharges and the isometric force. Our simulation results also show that EMG amplitude (estimated as the average rectified value) increases as a result of synchronous discharges of different motor units within the pool, but the magnitude of this increase is determined primarily by the action potential duration of the synchronized motor units. Furthermore, when the EMG effects are normalized to their maximum levels, motor unit synchrony does not exert significant effects on the form of the EMG-force relation, provided that the synchrony level is held similar at different excitation levels.

This article has been cited by other articles:

				D. Farina, C. Cescon, F. Negro, and R. M. Enoka Amplitude Cancellation of Motor-Unit Action Potentials in the Surface Electromyogram Can Be Estimated With Spike-Triggered Averaging J Neurophysiol, July 1, 2008; 100(1): 431 - 440. [Abstract] [Full Text] [PDF]

				T. J. Dartnall, M. A. Nordstrom, and J. G. Semmler Motor Unit Synchronization Is Increased in Biceps Brachii After Exercise-Induced Damage to Elbow Flexor Muscles J Neurophysiol, February 1, 2008; 99(2): 1008 - 1019. [Abstract] [Full Text] [PDF]

				T. D. Sanger Bayesian Filtering of Myoelectric Signals J Neurophysiol, February 1, 2007; 97(2): 1839 - 1845. [Abstract] [Full Text] [PDF]

				K. G. Keenan, D. Farina, R. Merletti, and R. M. Enoka Amplitude cancellation reduces the size of motor unit potentials averaged from the surface EMG J Appl Physiol, June 1, 2006; 100(6): 1928 - 1937. [Abstract] [Full Text] [PDF]

				D. Nozaki, K. Nakazawa, and M. Akai Uncertainty of knee joint muscle activity during knee joint torque exertion: the significance of controlling adjacent joint torque J Appl Physiol, September 1, 2005; 99(3): 1093 - 1103. [Abstract] [Full Text] [PDF]

				K. G. Keenan, D. Farina, K. S. Maluf, R. Merletti, and R. M. Enoka Influence of amplitude cancellation on the simulated surface electromyogram J Appl Physiol, January 1, 2005; 98(1): 120 - 131. [Abstract] [Full Text] [PDF]