title: Effects of the innervation zone on the time and frequency domain parameters of the surface electromyographic signal.
abstract: The purposes of the present study were to examine the effects of electrode placements over, proximal, and distal to the innervation zone (IZ) on electromyographic (EMG) amplitude (RMS) and frequency (MPF) responses during: (1) a maximal voluntary isometric contraction (MVIC), and; (2) a sustained, submaximal isometric muscle action. A linear array was used to record EMG signals from the vastus lateralis over the IZ, 30mm proximal, and 30mm distal to the IZ during an MVIC and a sustained isometric muscle action of the leg extensors at 50% MVIC. During the MVIC, lower EMG RMS (p>0.05) and greater EMG MPF (p<0.05) values were recorded over the IZ compared to away from the IZ, however, no differences in slope coefficients for the EMG RMS and MPF versus time relationships over, proximal, and distal to the IZ occurred. Thus, the results of the present study indicated that during an MVIC, EMG RMS and MPF values recorded over the IZ are not comparable to those away from the IZ. However, the rates of fatigue-induced changes in EMG RMS and MPF during sustained, submaximal isometric muscle actions of the leg extensors were the same regardless of the electrode placement locations relative to the IZ.
authors.affiliation: University of Nebraska - Lincoln, Lincoln, NE, United States. Electronic address: CSmith@unl.edu.
authors.forename: Cory M
authors.initials: CM
authors.lastname: Smith
authors.affiliation: University of Nebraska - Lincoln, Lincoln, NE, United States.
authors.forename: Terry J
authors.initials: TJ
authors.lastname: Housh
authors.affiliation: University of Kansas, Lawrence, KS, United States.
authors.forename: Trent J
authors.initials: TJ
authors.lastname: Herda
authors.affiliation: Creighton University, Omaha, NE, United States.
authors.forename: Jorge M
authors.initials: JM
authors.lastname: Zuniga
authors.affiliation: University of North Carolina - Chapel Hill, Chapel Hill, NC, United States.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Ryan
authors.affiliation: University of Wisconsin - La Crosse, La Crosse, WI, United States.
authors.forename: Clayton L
authors.initials: CL
authors.lastname: Camic
authors.affiliation: University of Kentucky, Lexington, KY, United States.
authors.forename: Haley C
authors.initials: HC
authors.lastname: Bergstrom
authors.affiliation: Oklahoma State University - Stillwater, Stillwater, OK, United States.
authors.forename: Doug B
authors.initials: DB
authors.lastname: Smith
authors.affiliation: University of Kansas, Lawrence, KS, United States.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Weir
authors.affiliation: University of Nebraska - Lincoln, Lincoln, NE, United States.
authors.forename: Joel T
authors.initials: JT
authors.lastname: Cramer
authors.affiliation: University of Nebraska - Lincoln, Lincoln, NE, United States.
authors.forename: Ethan C
authors.initials: EC
authors.lastname: Hill
authors.affiliation: University of Nebraska - Lincoln, Lincoln, NE, United States.
authors.forename: Kristen C
authors.initials: KC
authors.lastname: Cochrane
authors.affiliation: University of Nebraska - Lincoln, Lincoln, NE, United States.
authors.forename: Nathaniel D M
authors.initials: ND
authors.lastname: Jenkins
authors.affiliation: University of Nebraska - Lincoln, Lincoln, NE, United States.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Schmidt
authors.affiliation: University of Nebraska - Lincoln, Lincoln, NE, United States.
authors.forename: Glen O
authors.initials: GO
authors.lastname: Johnson
mesh_terms: D004566:Electrodes; D004576:Electromyography / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D052097:Quadriceps Muscle / Q000294:innervation* / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult
keywords: Amplitude; Electromyography; IZ; Linear array; MPF; Patterns of responses; RMS; Vastus lateralis