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01-01-2010 | Original Article

Influence of motor unit synchronization on amplitude characteristics of surface and intramuscularly recorded EMG signals

Authors: Todor I. Arabadzhiev, Vladimir G. Dimitrov, Nonna A. Dimitrova, George V. Dimitrov

Published in: European Journal of Applied Physiology | Issue 2/2010

Abstract

The increase in muscle strength without noticeable hypertrophic adaptations is very important in some sports. Motor unit (MU) synchronisation and higher rate of MU activation are proposed as possible mechanisms for such a strength and electromyogram (EMG) increase in the early phase of a training regimen. Root mean square and/or integrated EMG are amplitude measures commonly used to estimate the adaptive changes in efferent neural drive. EMG amplitude characteristics could change also because of alteration in intracellular action potential (IAP) spatial profile. We simulated MUs synchronization under different length of the IAP profile. Different synchronization was simulated by variation of the percent of discharges in a referent MU, to which a variable percent of remaining MUs was synchronized. Population synchrony index estimated the degree of MU synchronization in EMG signals. We demonstrate that the increase in amplitude characteristics due to MU synchronization is stronger in surface than in intramuscularly detected EMG signals. However, the effect of IAP profile lengthening on surface detected EMG signals could be much stronger than that of MU synchronization. Thus, changes in amplitude characteristics of surface detected EMG signals with progressive strength training could hardly be used as an indicator of changes in neural drive without testing possible changes in IAPs.

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Title: Influence of motor unit synchronization on amplitude characteristics of surface and intramuscularly recorded EMG signals
Authors: Todor I. Arabadzhiev
Vladimir G. Dimitrov
Nonna A. Dimitrova
George V. Dimitrov
Publication date: 01-01-2010
Publisher: Springer-Verlag
Published in: European Journal of Applied Physiology / Issue 2/2010
Print ISSN: 1439-6319
Electronic ISSN: 1439-6327
DOI: https://doi.org/10.1007/s00421-009-1206-3

At a glance: The STEP trials

Springer Medicine

Influence of motor unit synchronization on amplitude characteristics of surface and intramuscularly recorded EMG signals

Abstract

At a glance: The STEP trials

Springer Medicine

Abstract

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