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European Journal of Applied Physiology

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01-08-2014 | Original Article

The increase in surface EMG could be a misleading measure of neural adaptation during the early gains in strength

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

Published in: European Journal of Applied Physiology | Issue 8/2014

Abstract

Purpose

To test the validity of using the increase in surface EMG as a measure of neural adaptation during the early gains in strength.

Methods

Simulation of EMG signals detected by surface bipolar electrode with 20-mm inter-pole distance at different radial distances from the muscle and longitudinal distances from the end-plate area. The increases in the root mean square (RMS) of the EMG signal due to possible alteration in the neural drive or elevation of the intracellular negative after-potentials, detected in fast fatigable muscle fibres during post-tetanic potentiation and assumed to accompany post-activation potentiation, were compared.

Results

Lengthening of the intracellular action potential (IAP) profile due to elevation of the negative after-potentials could affect amplitude characteristics of surface EMG detected at any axial distance stronger than alteration in the neural drive. This was irrespective of the fact that the elevation of IAP negative after-potential was applied to fast fatigable motor units (MUs) only, while changes in frequency of activation (simulating neural drive changes) were applied to all MUs. In deeper muscles, where the fibre-electrode distance was larger, the peripheral effect was more pronounced. The normalization of EMG amplitude characteristics to an M-wave one could result only in partial elimination of peripheral factor influence

Conclusions

The increase in RMS of surface EMG during the early gains in strength should not be directly related to the changes in the neural drive. The relatively small but long-lasting elevated free resting calcium after high-resistance strength training could result in force potentiation and EMG increase.

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Title: The increase in surface EMG could be a misleading measure of neural adaptation during the early gains in strength
Authors: Todor I. Arabadzhiev
Vladimir G. Dimitrov
George V. Dimitrov
Publication date: 01-08-2014
Publisher: Springer Berlin Heidelberg
Published in: European Journal of Applied Physiology / Issue 8/2014
Print ISSN: 1439-6319
Electronic ISSN: 1439-6327
DOI: https://doi.org/10.1007/s00421-014-2893-y

At a glance: The STEP trials

Springer Medicine

The increase in surface EMG could be a misleading measure of neural adaptation during the early gains in strength

Abstract

Purpose

Methods

Results

Conclusions

At a glance: The STEP trials

Springer Medicine

Abstract

Purpose

Methods

Results

Conclusions

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