Vastus lateralis surface and single motor unit electromyography during shortening, lengthening and isometric contractions corrected for mode-dependent differences in force-generating capacity
| Autor: | C.J. de Ruiter, A. de Haan, P. W. L. Verdijk, Teatske M. Altenburg, W. van Mechelen |
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| Přispěvatelé: | Movement Behavior, Kinesiology, Faculty of Human Movement Sciences, Research Institute MOVE, Public and occupational health, MOVE Research Institute |
| Rok vydání: | 2009 |
| Předmět: |
musculoskeletal diseases
Adult Male Recruitment Neurophysiological medicine.medical_specialty Dynamic contractions Physiology Action Potentials Isometric exercise Electromyography Quadriceps Muscle Young Adult Voluntary contraction SDG 3 - Good Health and Well-being Internal medicine Isometric Contraction medicine Humans Knee Motor Neurons medicine.diagnostic_test Knee extensors Chemistry Anatomy Generating capacity musculoskeletal system Electric Stimulation Biomechanical Phenomena Motor unit Electrophysiology Torque Cardiology Female Muscle Contraction |
| Zdroj: | Altenburg, T M, de Ruiter, C J, Verdijk, P W L, van Mechelen, W & de Haan, A 2009, ' Vastus lateralis surface and single motor unit electromyography during shortening, lengthening and isometric contractions corrected for mode-dependent differences in force-generating capacity ', Acta Physiologica, vol. 196, no. 3, pp. 315-328 . https://doi.org/10.1111/j.1748-1716.2008.01941.x Acta Physiologica, 196(3), 315-328. Wiley-Blackwell |
| ISSN: | 1748-1708 |
| DOI: | 10.1111/j.1748-1716.2008.01941.x |
| Popis: | Knee extensor neuromuscular activity, rectified surface electromyography (rsEMG) and single motor unit EMG was investigated during isometric (60 degrees knee angle), shortening and lengthening contractions (50-70 degrees, 10 degrees s(-1)) corrected for force-velocity-related differences in force-generating capacity. However, during dynamic contractions additional factors such as shortening-induced force losses and lengthening-induced force gains may also affect force capacity and thereby neuromuscular activity. Therefore, even after correction for force-velocity-related differences in force capacity we expected neuromuscular activity to be higher and lower during shortening and lengthening, respectively, compared to isometric contractions.rsEMG of the three superficial muscle heads was obtained in a first session [10 and 50% maximal voluntary contraction (MVC)] and additionally EMG of (46) vastus lateralis motor units was recorded during a second session (4-76% MVC). Using superimposed electrical stimulation, force-generating capacity for shortening and lengthening contractions was found to be 0.96 and 1.16 times isometric (Iso) force capacity respectively. Therefore, neuromuscular activity during submaximal shortening and lengthening was compared with isometric contractions of respectively 1.04Iso (=1/0.96) and 0.86Iso (=1/1.16). rsEMG and discharge rates were normalized to isometric values.rsEMG behaviour was similar (P0.05) during both sessions. Shortening rsEMG (1.30 +/- 0.11) and discharge rate (1.22 +/- 0.13) were higher (P0.05) than 1.04Iso values (1.05 +/- 0.05 and 1.03 +/- 0.04 respectively), but lengthening rsEMG (1.05 +/- 0.12) and discharge rate (0.90 +/- 0.08) were not lower (P0.05) than 0.86Iso values (0.76 +/- 0.04 and 0.91 +/- 0.07 respectively).When force-velocity-related differences in force capacity were taken into account, neuromuscular activity was not lower during lengthening but was still higher during shortening compared with isometric contractions. |
| Databáze: | OpenAIRE |
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