Myoelectric manifestations of fatigue in vastus lateralis,medialis obliquus and medialis longus muscles |
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| Institution: | 1. Motor Science Research Center, SUISM Università degli Studi di Torino, P.za Bernini 12 10143, Torino, Italy;2. LISiN, Dipartimento di Elettronica, Politecnico di Torino, Torino, Italy;3. Division of Physiotherapy, The University of Queensland, Brisbane, Australia;4. Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Denmark;5. School of Physiotherapy, University of Melbourne, Australia;1. Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo, Japan;2. Department of Radiobiology and Medical Engineering, Hokkaido University Graduate School of Medicine, Sapporo, Japan;3. Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo, Japan;1. Athletic Training and Sports Medicine Research Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania, U.S.A.;2. Penn State Hershey Bone and Joint Institute, State College, State College, Pennsylvania, U.S.A.;1. Department of Neurology and Clinical Neurophysiology and Department of Neurosurgery, Medisch Spectrum Twente, Enschede, The Netherlands;2. SEIN Centre of Excellence for Epilepsy and Sleep Medicine, Zwolle, The Netherlands;3. MIRA Institute for Biomedical Engineering and Technical Medicine, University of Twente, Enschede, The Netherlands;1. Faculty of Kinesiology, Human Performance Laboratory, University of Calgary, 2500 University Dr. NW, Calgary, Alberta T2N 1N4, Canada;2. Dept. of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, Ontario, Canada;1. Faculty of Health and Life Sciences, Department of Sport, Exercise, and Rehabilitation, Northumbria University, Newcastle, UK;2. Water Research Group, School of Environmental Sciences and Development, Northwest University, Potchefstroom, South Africa;3. Program in Exercise Science, Department of Physical Therapy, Marquette University, Milwaukee, USA |
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| Abstract: | The purpose of this study was to determine whether surface electromyography (EMG) assessment of myoelectric manifestations of muscle fatigue is capable of detecting differences between the vastus lateralis and medialis muscles which are consistent with the results of previous biopsy studies. Surface EMG signals were recorded from the vastus medialis longus (VML), vastus medialis obliquus (VMO) and vastus lateralis (VL) muscles during isometric knee extension contractions at 60% and 80% of the maximum voluntary contraction (MVC) for 10 s and 60 s, respectively. Initial values and rate of change of mean frequency (MNF), average rectified value (ARV) and conduction velocity (CV) of the EMG signal were calculated. Comparisons between the two force levels revealed that the initial values of MNF for the VL muscle were greater at 80% MVC compared to 60% MVC (P < 0.01). Comparisons between the vasti muscles demonstrated lower initial values of CV for VMO compared to VL at 60% MVC (P < 0.01) and lower than VML and VL at 80% MVC (P < 0.01). In addition, initial values of MNF were higher for VL with respect to both VML and VMO at 80% MVC (P < 0.01) and initial estimates of ARV were higher for VMO compared to VML at both force levels (P < 0.01 at 60% MVC and P < 0.05 at 80% MVC). For the sustained contraction at 80% MVC, VL demonstrated a greater decrease in CV over time compared to VMO (P < 0.05).These findings suggest that surface EMG signals and their time course during sustained isometric contractions may be useful to non-invasively describe functional differences between the vasti muscles. |
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