title: Muscle activity detection in electromyograms recorded during periodic movements.
abstract: Muscle coordination during periodic movements is often studied using the average envelope of the electromyographic (EMG) signal. We show that this method causes a loss of important information, and potentially gives rise to errors in analysis of muscle activity coordination. We created four simulated two-channel surface EMG signals, in order to compare the results of muscle onset/cessation detection, performed on the average EMG envelope and the EMG envelopes in every single movement cycle. Our results show that the common method using the average EMG envelope is unable to reveal certain important characteristics of the EMG signals, while the analysis performed on individual cycles accentuates this information. This ability was verified on 16-channel surface EMGs obtained during walking and cycling. By detecting muscle activity in individual movement cycles, we could observe fine changes in muscle coordination. Moreover, muscles with questionable reliability of activity detection were distinguished and highlighted in the presented summary figures. In the second part of the paper, our publicly available set of MATLAB files for surface EMG signal processing is described.
authors.affiliation: Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Technická 2, 166 27 Praha 6, Czech Republic. Electronic address: daniel.spulak@gmail.com.
authors.forename: Daniel
authors.initials: D
authors.lastname: Spulák
authors.affiliation: Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Technická 2, 166 27 Praha 6, Czech Republic.
authors.forename: Roman
authors.initials: R
authors.lastname: Cmejla
authors.affiliation: Department of Outdoor Sports, Faculty of Physical Education and Sport, Charles University in Prague, José Martího 31, 162 52 Praha 6, Czech Republic.
authors.forename: Radka
authors.initials: R
authors.lastname: Bačáková
authors.affiliation: Department of Outdoor Sports, Faculty of Physical Education and Sport, Charles University in Prague, José Martího 31, 162 52 Praha 6, Czech Republic.
authors.forename: Bronislav
authors.initials: B
authors.lastname: Kračmar
authors.affiliation: Department of Outdoor Sports, Faculty of Physical Education and Sport, Charles University in Prague, José Martího 31, 162 52 Praha 6, Czech Republic.
authors.forename: Lenka
authors.initials: L
authors.lastname: Satrapová
authors.affiliation: Department of Outdoor Sports, Faculty of Physical Education and Sport, Charles University in Prague, José Martího 31, 162 52 Praha 6, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Novotný
mesh_terms: D001642:Bicycling / Q000502:physiology; D003198:Computer Simulation; D004576:Electromyography / Q000379:methods*; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D014584:User-Computer Interface
keywords: Averaging; Electromyography; Kinesiology; Muscle activation pattern; Muscle activity detection; Periodic movements; Signal processing