EMG activity of low back extensor muscles during cyclic flexion/extension |
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| Authors: | Gwanseob Shin Clive D’Souza |
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| Affiliation: | 1. Department of Physical Therapy, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran;2. Department of Physical Therapy, School of Rehabilitation, Iran University of Medical Sciences, Tehran, Iran;1. Center for Musculoskeletal Medicine & Rehabilitation, Military Hospital Queen Astrid, Brussels, Belgium;2. Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium;3. Department of Mathematics, Royal Military Academy, Brussels, Belgium;4. Department of Experimental Clinical and Health Psychology, Faculty of Psychology and Educational Sciences, Ghent University, Ghent, Belgium;1. Institute for Performance Research, Department of Exercise and Sport Science, Manchester Metropolitan University, Crewe Green Rd., Crewe, Cheshire CW1 5DU, UK;2. Pennine Acute Hospitals NHS Trust, North Manchester General Hospital, Manchester M8 5RB, UK;3. Research Institute for Health and Social Change, Manchester Metropolitan University, Manchester M13 0JA, UK;1. Department of Bio-Industrial Mechatronics Engineering, National Taiwan University, Taiwan, ROC;2. School of Physical Therapy, National Taiwan University, Taiwan, ROC;3. Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taiwan, ROC;1. Department of Industrial and Management Systems Engineering, West Virginia University, Morgantown, WV 26506, USA;2. Division of Kinesiology and Health, University of Wyoming, Laramie, WY 82071, USA |
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| Abstract: | Cyclic trunk flexion/extension is known to be a risk factor for low back pain or disorders. Changes in the in vivo low back musculature associated with cyclic flexion/extension have not been adequately examined. The purpose of this study was to investigate the effects of cyclic flexion/extension on muscle activity of the low back extensors by quantifying changes in activation timing and mean amplitude of electromyography (EMG). Trunk flexion angle and EMG were recorded during 30 cyclic flexion/extension movements over a 5 min period, and during isometric extension performed before and after the 5 min period. Mean EMG in isometric extension increased (30% increase in average) significantly after cyclic flexion/extension, confirming a transfer of extension moment from viscoelastic passive tissues to the extensor muscles in isometric extension. However, in the extension phase of cyclic flexion/extension, a significant delay in the re-activation and a decrease in the mean amplitude of EMG were observed. The results of this study, together with findings in previous research, suggest that the biomechanical effects and potential risk associated with cyclic flexion/extension may be sensitive to the task demands. Further research is needed to investigate how different moment generating components function together to compensate for the loss of tissue stiffness under varying task conditions. |
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