title: Electromyographic Responses from the Vastus Medialis during Isometric Muscle Actions.
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.
authors.affiliation: Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, United States.
authors.forename: C M
authors.initials: CM
authors.lastname: Smith
authors.affiliation: Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, United States.
authors.forename: T J
authors.initials: TJ
authors.lastname: Housh
authors.affiliation: Health, Sport and Exercise Science, University of Kansas, Lawrence, United States.
authors.forename: T
authors.initials: T
authors.lastname: Herda
authors.affiliation: Exercise Science, Creighton University, Omaha, United States.
authors.forename: J M
authors.initials: JM
authors.lastname: Zuniga
authors.affiliation: Exercise & Sport Science, University of Wisconsin - La Crosse, La Crosse, United States.
authors.forename: C L
authors.initials: CL
authors.lastname: Camic
authors.affiliation: Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, United States.
authors.forename: H C
authors.initials: HC
authors.lastname: Bergstrom
authors.affiliation: Health and Human Performance, Oklahoma State University, Stillwater, United States.
authors.forename: D B
authors.initials: DB
authors.lastname: Smith
authors.affiliation: Health, Sport and Exercise Science, University of Kansas, Lawrence, United States.
authors.forename: J P
authors.initials: JP
authors.lastname: Weir
authors.affiliation: Department of Nutrition & Health Sciences, University of Nebraska-Lincoln, Lincoln, United States.
authors.forename: J T
authors.initials: JT
authors.lastname: Cramer
authors.affiliation: Nutrition and Health Sciences, Ethan Hill, Lincoln, United States.
authors.forename: E C
authors.initials: EC
authors.lastname: Hill
authors.affiliation: Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, United States.
authors.forename: K C
authors.initials: KC
authors.lastname: Cochrane
authors.affiliation: Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, United States.
authors.forename: N D M
authors.initials: ND
authors.lastname: Jenkins
authors.affiliation: Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, United States.
authors.forename: R J
authors.initials: RJ
authors.lastname: Schmidt
authors.affiliation: Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, United States.
authors.forename: G
authors.initials: G
authors.lastname: Johnson
mesh_terms: D004566:Electrodes; D004576:Electromyography / Q000379:methods*; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D052097:Quadriceps Muscle / Q000294:innervation / Q000502:physiology*; D055815:Young Adult