The Experts below are selected from a list of 4065 Experts worldwide ranked by ideXlab platform
Alain Martin - One of the best experts on this subject based on the ideXlab platform.
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effect of angular velocity on soleus and medial gastrocnemius h reflex during maximal concentric and Eccentric Muscle Contraction
Journal of Electromyography and Kinesiology, 2009Co-Authors: Julien Duclay, Alain Martin, Alice Robbe, M PoussonAbstract:Abstract At rest, the H-reflex is lower during lengthening than shortening actions. During passive lengthening, both soleus (SOL) and medial gastrocnemius (MG) H-reflex amplitudes decrease with increasing angular velocity. This study was designed to investigate whether H-reflex amplitude is affected by angular velocity during concentric and Eccentric maximal voluntary Contraction (MVC). Experiments were performed on nine healthy men. At a constant angular velocity of 60°/s and 20°/s, maximal H-reflex and M-wave potentials were evoked at rest (i.e., H max and M max , respectively) and during concentric and Eccentric MVC (i.e., H sup and M sup , respectively). Regardless of the Muscle, H max /M max was lower during lengthening than shortening actions and the H sup /M sup ratio was higher than H max /M max during lengthening actions. Whereas no action type and angular velocity effects on the MG H sup /M sup were found, the SOL H sup /M sup was lower during Eccentric than concentric MVC and this depression was increased with higher angular velocity. Our findings indicate that the depression of the H-reflex amplitude during Eccentric compared to concentric MVC depends mainly on the amount of inhibition induced by lengthening action. In conclusion, H-reflex should be evoked during both passive and active dynamic trials to evaluate the plasticity of the spinal loop.
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evoked h reflex and v wave responses during maximal isometric concentric and Eccentric Muscle Contraction
Journal of Neurophysiology, 2005Co-Authors: Julien Duclay, Alain MartinAbstract:This study was designed to investigate the modulations of H-reflex and V-wave responses during passive and maximal active dynamic actions. Experiments were performed on 16 healthy males [age: 24 ± ...
Guang Bai - One of the best experts on this subject based on the ideXlab platform.
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Eccentric Muscle Contraction and stretching evoke mechanical hyperalgesia and modulate cgrp and p2x3 expression in a functionally relevant manner
Pain, 2010Co-Authors: Dean Dessem, Ranjinidevi Ambalavanar, Melena Evancho, Aicha Moutanni, Chandrasekhar Yallampalli, Guang BaiAbstract:Abstract Non-invasive, movement-based models were used to investigate Muscle pain. In rats, the masseter Muscle was rapidly stretched or electrically stimulated during forced lengthening to produce Eccentric Muscle Contractions (EC). Both EC and stretching disrupted scattered myofibers and produced intramuscular plasma extravasation. Pro-inflammatory cytokines (IL-1β, TNF-α, IL-6) and vascular endothelial growth factor (VEGF) were elevated in the masseter 24 h following EC. At 48 h, neutrophils increased and ED1 macrophages infiltrated myofibers while ED2 macrophages were abundant at 4d. Mechanical hyperalgesia was evident in the ipsilateral head 4 h–4d after a single bout of EC and for 7d following multiple bouts (1 bout/d for 4d). Calcitonin gene-related peptide (CGRP) mRNA increased in the trigeminal ganglion 24 h following EC while immunoreactive CGRP decreased. By 2d, CGRP-Muscle afferent numbers equaled naive numbers implying that CGRP is released following EC and replenished within 2d. EC elevated P2X 3 mRNA and increased P2X 3 Muscle afferent neuron number for 12d while electrical stimulation without Muscle Contraction altered neither CGRP nor P2X 3 mRNA levels. Muscle stretching produced hyperalgesia for 2d whereas Contraction alone produced no hyperalgesia. Stretching increased CGRP mRNA at 24 h but not CGRP-Muscle afferent number at 2–12d. In contrast, stretching significantly increased the number of P2X 3 Muscle afferent neurons for 12d. The sustained, elevated P2X 3 expression evoked by EC and stretching may enhance nociceptor responsiveness to ATP released during subsequent myofiber damage. Movement-based actions such as EC and Muscle stretching produce unique tissue responses and modulate neuropeptide and nociceptive receptor expression in a manner particularly relevant to repeated Muscle damage.
Julien Duclay - One of the best experts on this subject based on the ideXlab platform.
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effect of angular velocity on soleus and medial gastrocnemius h reflex during maximal concentric and Eccentric Muscle Contraction
Journal of Electromyography and Kinesiology, 2009Co-Authors: Julien Duclay, Alain Martin, Alice Robbe, M PoussonAbstract:Abstract At rest, the H-reflex is lower during lengthening than shortening actions. During passive lengthening, both soleus (SOL) and medial gastrocnemius (MG) H-reflex amplitudes decrease with increasing angular velocity. This study was designed to investigate whether H-reflex amplitude is affected by angular velocity during concentric and Eccentric maximal voluntary Contraction (MVC). Experiments were performed on nine healthy men. At a constant angular velocity of 60°/s and 20°/s, maximal H-reflex and M-wave potentials were evoked at rest (i.e., H max and M max , respectively) and during concentric and Eccentric MVC (i.e., H sup and M sup , respectively). Regardless of the Muscle, H max /M max was lower during lengthening than shortening actions and the H sup /M sup ratio was higher than H max /M max during lengthening actions. Whereas no action type and angular velocity effects on the MG H sup /M sup were found, the SOL H sup /M sup was lower during Eccentric than concentric MVC and this depression was increased with higher angular velocity. Our findings indicate that the depression of the H-reflex amplitude during Eccentric compared to concentric MVC depends mainly on the amount of inhibition induced by lengthening action. In conclusion, H-reflex should be evoked during both passive and active dynamic trials to evaluate the plasticity of the spinal loop.
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evoked h reflex and v wave responses during maximal isometric concentric and Eccentric Muscle Contraction
Journal of Neurophysiology, 2005Co-Authors: Julien Duclay, Alain MartinAbstract:This study was designed to investigate the modulations of H-reflex and V-wave responses during passive and maximal active dynamic actions. Experiments were performed on 16 healthy males [age: 24 ± ...
Arnaud Guevel - One of the best experts on this subject based on the ideXlab platform.
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Neuromuscular and Muscle-tendon system adaptations to isotonic and isokinetic Eccentric exercise
Annals of Physical and Rehabilitation Medicine, 2010Co-Authors: Gaël Guilhem, Catherine Cornu, Arnaud GuevelAbstract:OBJECTIVE: To present the properties of an Eccentric Contraction and compare neuromuscular and Muscle-tendon system adaptations induced by isotonic and isokinetic Eccentric trainings.\n\nSYNTHESIS: An Eccentric Muscle Contraction is characterized by the production of Muscle force associated to a lengthening of the Muscle-tendon system. This Muscle solicitation can cause micro lesions followed by a regeneration process of the Muscle-tendon system. Eccentric exercise is commonly used in functional rehabilitation for its positive effect on collagen synthesis but also for resistance training to increase Muscle strength and Muscle mass in athletes. Indeed, Eccentric training stimulates Muscle hypertrophy, increases the fascicle pennation angle, fascicles length and neural activation, thus inducing greater strength gains than concentric or isometric training programs. Eccentric exercise is commonly performed either against a constant external load (isotonic) or at constant velocity (isokinetic), inducing different mechanical constraints. These different mechanical constraints could induce structural and neural adaptive strategies specific to each type of exercise.\n\nCONCLUSION: The literature tends to show that isotonic mode leads to a greater strength gain than isokinetic mode. This observation could be explained by a greater neuromuscular activation after IT training. However, the specific Muscle adaptations induced by each mode remain difficult to determine due to the lack of standardized, comparative studies.
Guang H Yue - One of the best experts on this subject based on the ideXlab platform.
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brain functional connectivity is different during voluntary concentric and Eccentric Muscle Contraction
Frontiers in Physiology, 2016Co-Authors: Wan X Yao, Zhiguo Jiang, Yufei Huang, Jack L Lancaster, Changhao Jiang, Crystal G Franlin, Guang H YueAbstract:Previous studies report greater activation in the cortical motor network in controlling Eccentric Contraction (EC) than concentric Contraction (CC) of human skeletal Muscles despite lower activation level of the Muscle associated with EC. It is unknown, however, whether the strength of functional coupling between the primary motor cortex (M1) and other involved areas in the brain differs as voluntary movements are controlled by a network of regions in the primary, secondary and association cortices. Examining fMRI-based functional connectivity (FC) offers an opportunity to measure strength of such coupling. To address the question, we examined functional MRI (fMRI) data acquired during EC and CC (20 Contractions each with similar movement distance and speed) of the right first dorsal interosseous (FDI) Muscle in 11 young (20-32 years) and healthy individuals and estimated FC between the M1 and a number of cortical regions in the motor control network. The major findings from the mechanical and fMRI-based FC analysis were that (1) no significant differences were seen in movement distance, speed and stability between the EC and CC; (2) significantly stronger mean FC was found for CC than EC. Our finding provides novel insights for a better understanding of the control mechanisms underlying voluntary movements produced by EC and CC. The finding is potentially helpful for guiding the development of targeted sport training and/or therapeutic programs for performance enhancement and injury prevention.
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aging interferes central control mechanism for Eccentric Muscle Contraction
Frontiers in Aging Neuroscience, 2014Co-Authors: Wan X Yao, Zhiguo Jiang, Jiahong Gao, Crystal Franklin, Yufei Huang, Jack L Lancaster, Guang H YueAbstract:Previous studies report greater activation in the cortical motor network in controlling Eccentric Contraction (EC) than concentric Contraction (CC) despite lower Muscle activation level associated with EC vs. CC in healthy, young individuals. It is unknown, however, whether elderly people exhibiting increased difficulties in performing EC than CC possess this unique cortical control mechanism for EC movements. To address this question, we examined functional MRI (fMRI) data acquired during EC and CC of the first dorsal interosseous (FDI) Muscle in 11 young (20-32 years) and 9 old (67-73 years) individuals. During the fMRI experiment, all subjects performed 20 CC and 20 EC of the right FDI with the same angular distance and velocity. The major findings from the behavioral and fMRI data analysis were that (1) movement stability was poorer in EC than CC in the old but not the young group; (2) similar to previous electrophysiological and fMRI reports, the EC resulted in significantly stronger activation in the motor control network consisting of primary, secondary and association motor cortices than CC in the young and old groups; (3) the biased stronger activation towards EC was significantly greater in the old than the young group especially in the secondary and association cortices such as supplementary and premotor motor areas and anterior cingulate cortex; and (4) in the primary motor and sensory cortices, the biased activation towards EC was significantly greater in the young than the old group. Greater activation in higher-order cortical fields for controlling EC movement by elderly adults may reflect activities in these regions to compensate for aging-related impairments in the ability to control complex EC movements. Our finding is useful for potentially guiding the development of targeted therapies to counteract age-related movement deficits and to prevent injury.