title: Accuracy of three different techniques for automatically estimating innervation zone location.
abstract: The purpose of this study was to compare the accuracy of the estimated innervation zone (IZ) locations obtained from cross-correlation, the minimum amplitude, and maximum center frequency criteria. Eight healthy men (mean±SD age=23.0±4.3 yrs) performed isometric muscle actions of the leg extensors, and 15 separate bipolar surface electromyographic (EMG) signals were detected from the vastus lateralis. A custom software program was used to estimate the location of the IZ based on: (1) the EMG channel that demonstrated the lowest amplitude, (2) the EMG channel that showed the highest mean frequency, and (3) the EMG channel that demonstrated the lowest peak cross-correlation between the signals from adjacent channels. The IZ location estimates from the lowest amplitude and highest mean frequency criteria were accurate in only 43.75% and 7.5% of the cases, respectively. The accuracy of the cross-correlation-based method was 90%. The cross-correlation-based method was much more accurate for estimating IZ location than were the lowest amplitude and highest mean frequency criteria. Cross-correlation could potentially be used for estimating the location of the IZ without the need for visual inspection of EMG signals.
authors.affiliation: Department of Health and Exercise Science, University of Oklahoma, 110 Huston Huffman Center, Norman, OK, USA. tbeck@ou.edu
authors.forename: Travis W
authors.initials: TW
authors.lastname: Beck
authors.forename: Jason M
authors.initials: JM
authors.lastname: DeFreitas
authors.forename: Matt S
authors.initials: MS
authors.lastname: Stock
mesh_terms: D000328:Adult; D004576:Electromyography / Q000379:methods*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D007866:Leg / Q000294:innervation / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000294:innervation* / Q000502:physiology; D052097:Quadriceps Muscle / Q000502:physiology