Research article summary:

Analysis and simulation of changes in EMG amplitude during high-level fatiguing contractions.

Abstract Extract:
Changes in surface electromyographic (EMG) amplitude during sustained, fatiguing contractions are commonly attributed to variations in muscle fiber conduction velocity (MFCV), motor unit firing rates, transmembrane action potentials and the ... (Full abstract text below)

Published 2003Sep in Journal: IEEE Trans Biomed Eng (Language : eng)

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1. IEEE Trans Biomed Eng. 2003 Sep;50(9):1052-62

Analysis and simulation of changes in EMG amplitude during high-level fatiguing contractions.

Lowery MM, O'Malley MJ

Rehabilitation Institute of Chicago, 345 E. Superior St, Chicago, Illinois 60611, USA. m-lowery@northwestern.edu

Changes in surface electromyographic (EMG) amplitude during sustained, fatiguing contractions are commonly attributed to variations in muscle fiber conduction velocity (MFCV), motor unit firing rates, transmembrane action potentials and the synchronization or recruitment of motor units. However, the relative contribution of each factor remains unclear. Analytical relationships relating changes in MFCV and mean motor unit firing rates to the root mean square (RMS) and average rectified (AR) value of the surface EMG signal are derived. The relationships are then confirmed using model simulation. The simulations and analysis illustrate the different behaviors of the surface EMG RMS and AR value with changing MFCV and firing rate, as the level of motor unit superposition varies. Levels of firing rate modulation and short-term synchronization that, combined with variations in MFCV, could cause changes in EMG amplitude similar to those observed during sustained isometric contraction of the brachioradialis at 80% of maximum voluntary contraction were estimated. While it is not possible to draw conclusions about changes in neural control without further information about the underlying motor unit activation patterns, the examples presented illustrate how a combined analytical and simulation approach may provide insight into the manner in which different factors affect EMG amplitude during sustained isometric contractions.

PMID : 12943273 [PubMed - Indexed for MEDLINE]

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Full Author Information

First Name	LastName	Initials
Madeleine M	Lowery	MM
Mark J	O'Malley	MJ

Affiliation: Rehabilitation Institute of Chicago, 345 E. Superior St, Chicago, Illinois 60611, USA. m-lowery@northwestern.edu

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