Electromyographic Responses from the Vastus Medialis during Isometric Muscle Actions

Authors

C. M. Smith, University of Nebraska-Lincoln
Terry J. Housh, University of Nebraska-LincolnFollow
Trent J. Herda, University of KansasFollow
Jorge M Zuniga, Creighton UniversityFollow
Clayton L. Camic, University of Wisconsin-La CrosseFollow
Haley Bergstrom, University of Nebraska-LincolnFollow
D.B. Smith, Oklahoma State University
John R. Weir, Oklahoma State UniversityFollow
Joel T. Cramer, University of Nebraska-LincolnFollow
E.C. Hill, Nutrition and Health Sciences
Kristen C. Cochrane, University of Nebraska - LincolnFollow
N. D. M. Jenkins, University of Nebraska-Lincoln
R. Schmidt, University of Nebraska-LincolnFollow
G. Johnson, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

8-25-2015

Citation

Georg Thieme Verlag KG Stuttgart · New York ISSN 0172-4622

Comments

Smith CM et al. Electromyographic Responses from the … Int J Sports Med 2016; 37: 647–652

Abstract

This study examined the electromyographic (EMG) responses from the vastus medialis (VM) for electrodes placed over and away from the innervation zone (IZ) during a maximal voluntary isometric contraction (MVIC) and sustained, submaximal isometric muscle action. A linear electrode array was placed on the VM to identify the IZ and muscle fiber pennation angle during an MVIC and sustained isometric muscle action at 50 % MVIC. EMG amplitude and frequency parameters were determined from 7 bipolar channels of the electrode array, including over the IZ, as well as 10 mm, 20 mm and 30 mm proximal and distal to the IZ. There were no differences between the channels for the patterns of responses for EMG amplitude or mean power frequency during the sustained, submaximal isometric muscle action; however, there were differences between channels during the MVIC. The results of the present study supported the need to standardize the placement of electrodes on the VM for the assessment of EMG amplitude and mean power frequency. Based on the current findings, it is recommended that electrode placements be distal to the IZ and aligned with the muscle fiber pennation angle during MVICs, as well as sustained, submaximal isometric muscle actions.