title: The effects of accelerometer placement on mechanomyographic amplitude and mean power frequency during cycle ergometry.
abstract: The purposes of this study were threefold: (1) to compare the power output related patterns of absolute and normalized MMG amplitude and MPF responses for proximal and distal accelerometer placements on the vastus lateralis (VL) muscle during incremental cycle ergometry; (2) to examine the influence of accelerometer placements on mean absolute MMG amplitude and MPF values; and (3) to determine the effects of normalization on mean MMG amplitude and MPF values from proximal and distal accelerometer placements. Fifteen adults (10 men and 5 women; mean+/-SD age=23.9+/-3.1 years) performed incremental cycle ergometry tests to exhaustion. Two accelerometers were placed proximal and distal on the VL muscle. Paired t-tests indicated that absolute MMG amplitude values for the proximal accelerometer were greater (p<0.05) than the distal accelerometer at all power outputs. The normalized MMG amplitude also had greater values for the proximal accelerometer at all power outputs, except 50W. There were no differences, however, between proximal and distal accelerometers for absolute MMG MPF, except at 75W, and normalization eliminated this difference. Twenty-seven percent of the subjects exhibited different power output related patterns of responses between accelerometer placements for MMG amplitude and 47% exhibited different patterns for MPF. These findings indicated that normalization did not eliminate the influence of accelerometer placement on MMG amplitude and highlighted the importance of standardizing accelerometer placements to compare MMG values during cycle ergometry.
authors.affiliation: Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, NE 68583, United States. jzuniga2@unlserve.unl.edu
authors.forename: Jorge M
authors.initials: JM
authors.lastname: Zuniga
authors.forename: Terry J
authors.initials: TJ
authors.lastname: Housh
authors.forename: Clayton L
authors.initials: CL
authors.lastname: Camic
authors.forename: C Russell
authors.initials: CR
authors.lastname: Hendrix
authors.forename: Michelle
authors.initials: M
authors.lastname: Mielke
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Schmidt
authors.forename: Glen O
authors.initials: GO
authors.lastname: Johnson
mesh_terms: D001696:Biomechanical Phenomena; D004576:Electromyography; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D009213:Myography; D052097:Quadriceps Muscle / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult