caa a22 4500 467941386 CHVBK 20180406153013.0 cr unu---uuuuu 170328e20060101xx s 000 0 eng 10.1007/s00421-004-1261-8 doi (NATIONALLICENCE)springer-10.1007/s00421-004-1261-8 Single motor unit and spectral surface EMG analysis during low-force, sustained contractions of the upper trapezius muscle [Elektronische Daten] [Dario Farina, Daniel Zennaro, Marco Pozzo, Roberto Merletti, Thomas Läubli] Intramuscular and surface electromyographic (EMG) activities were recorded from the left and right upper trapezius muscle of eight healthy male subjects during 5-min long static contractions at 2% and 5% of the maximal voluntary contraction (MVC) force. Intramuscular signals were detected by wire electrodes while surface EMG signals were recorded with linear adhesive electrode arrays. The surface EMG signals were averaged using the potentials extracted from the intramuscular EMG decomposition as triggers. The conduction velocity of single motor units (MUs) was estimated over time from the averaged surface potentials while average rectified value and mean power spectral frequency were computed over time from 0.5s epochs of surface EMG signal. It was found that (1) MUs were progressively recruited after the beginning of sustained contractions of the upper trapezius muscle at 2% and 5% MVC, (2) the conduction velocity of the MUs active since the beginning of the contraction significantly decreased over time, and (3) although the CV of single MUs significantly decreased, the mean power spectral frequency of the surface EMG did not show a consistent trend over time. It was concluded that spectral surface EMG analysis, being affected by many physiological mechanisms, may show limitations for the objective assessment of localized muscle fatigue during low force, sustained contractions. On the contrary, single motor unit conduction velocity may provide an early indication of changes in muscle fiber membrane properties with sustained activity. Springer-Verlag, 2004 Electromyography nationallicence Muscle fatigue nationallicence Motor unit nationallicence Upper trapezius nationallicence Farina Dario Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7 D-3, 9220, Aalborg, Denmark aut Zennaro Daniel Institute of Hygiene and Applied Physiology, Swiss Federal Institute of Technology Zurich, Zurich, Switzerland aut Pozzo Marco Laboratorio di Ingegneria del Sistema Neuromuscolare, Dip. Elettronica, Politecnico di Torino, Turin, Italy aut Merletti Roberto Laboratorio di Ingegneria del Sistema Neuromuscolare, Dip. Elettronica, Politecnico di Torino, Turin, Italy aut Läubli Thomas Institute of Hygiene and Applied Physiology, Swiss Federal Institute of Technology Zurich, Zurich, Switzerland aut European Journal of Applied Physiology Springer-Verlag 96/2(2006-01-01), 157-164 1439-6319 96:2<157 2006 96 421 https://doi.org/10.1007/s00421-004-1261-8 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00421-004-1261-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Farina Dario Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7 D-3, 9220, Aalborg, Denmark aut NATIONALLICENCE 700 1- Zennaro Daniel Institute of Hygiene and Applied Physiology, Swiss Federal Institute of Technology Zurich, Zurich, Switzerland aut NATIONALLICENCE 700 1- Pozzo Marco Laboratorio di Ingegneria del Sistema Neuromuscolare, Dip. Elettronica, Politecnico di Torino, Turin, Italy aut NATIONALLICENCE 700 1- Merletti Roberto Laboratorio di Ingegneria del Sistema Neuromuscolare, Dip. Elettronica, Politecnico di Torino, Turin, Italy aut NATIONALLICENCE 700 1- Läubli Thomas Institute of Hygiene and Applied Physiology, Swiss Federal Institute of Technology Zurich, Zurich, Switzerland aut NATIONALLICENCE 773 0- European Journal of Applied Physiology Springer-Verlag 96/2(2006-01-01), 157-164 1439-6319 96:2<157 2006 96 421 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer