Imperial College London
Portrait Picture

ProfessorDarioFarina

Faculty of Engineering, Department of Bioengineering

Chair in Neurorehabilitation Engineering
 
 
 
//

Contact

 

+44 (0)20 7594 1387d.farina Website

 
 
//

Location

 

RSM 4.15Royal School of MinesSouth Kensington Campus

//

Summary

 

Publications

Citation

BibTex format

@article{Martinez-Valdes:2018:10.1152/japplphysiol.01115.2017,
author = {Martinez-Valdes, E and Negro, F and Falla, D and De, Nunzio AM and Farina, D},
doi = {10.1152/japplphysiol.01115.2017},
journal = {J Appl Physiol (1985)},
pages = {1071--1079},
title = {Surface electromyographic amplitude does not identify differences in neural drive to synergistic muscles.},
url = {http://dx.doi.org/10.1152/japplphysiol.01115.2017},
volume = {124},
year = {2018}
}
Download

RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Surface electromyographic (EMG) signal amplitude is typically used to compare the neural drive to muscles. We experimentally investigated this association by studying the motor unit (MU) behavior and action potentials in the vastus medialis (VM) and vastus lateralis (VL) muscles. Eighteen participants performed isometric knee extensions at four target torques [10, 30, 50, and 70% of the maximum torque (MVC)] while high-density EMG signals were recorded from the VM and VL. The absolute EMG amplitude was greater for VM than VL ( P < 0.001), whereas the EMG amplitude normalized with respect to MVC was greater for VL than VM ( P < 0.04). Because differences in EMG amplitude can be due to both differences in the neural drive and in the size of the MU action potentials, we indirectly inferred the neural drives received by the two muscles by estimating the synaptic inputs received by the corresponding motor neuron pools. For this purpose, we analyzed the increase in discharge rate from recruitment to target torque for motor units matched by recruitment threshold in the two muscles. This analysis indicated that the two muscles received similar levels of neural drive. Nonetheless, the size of the MU action potentials was greater for VM than VL ( P < 0.001), and this difference explained most of the differences in EMG amplitude between the two muscles (~63% of explained variance). These results indicate that EMG amplitude, even following normalization, does not reflect the neural drive to synergistic muscles. Moreover, absolute EMG amplitude is mainly explained by the size of MU action potentials. NEW & NOTEWORTHY Electromyographic (EMG) amplitude is widely used to compare indirectly the strength of neural drive received by synergistic muscles. However, there are no studies validating this approach with motor unit data. Here, we compared between-muscles differences in surface EMG amplitude and motor unit behavior. The results clarify the limitations of surface EM
AU  - Martinez-Valdes,E
AU  - Negro,F
AU  - Falla,D
AU  - De,Nunzio AM
AU  - Farina,D
DO  - 10.1152/japplphysiol.01115.2017
EP  - 1079
PY  - 2018///
SP  - 1071
TI  - Surface electromyographic amplitude does not identify differences in neural drive to synergistic muscles.
T2  - J Appl Physiol (1985)
UR  - http://dx.doi.org/10.1152/japplphysiol.01115.2017
UR  - https://www.ncbi.nlm.nih.gov/pubmed/29420155
VL  - 124
ER  -
Download