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Scutter, Sheila. "H-reflex in human masseter." Title page, contents and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phs4377.pdf.
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Copies of author's previously published articles inserted. Bibliography: leaves 172-204. H-relexes are used to determine the reflex connections of muscle spindle afferents, the exitability of the motorneuron pool and the integrity of the reflex pathways. However, H-relexes are small and can be difficult to elicit in the masseter, limiting their use in the investigation of the masticatory system. This study investigated the recruitment of masseter motorneurons into the H-reflex, compared to the recruitment occuring during voluntary isometric biting, to determine the distribution of the effective muscle spindle input.
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Grünewald, Matthias Lars. "Einfluss des Anästhetikuns Sevofluran und schmerzhafter Stimuli auf den H-Reflex." Doctoral thesis, Humboldt-Universität zu Berlin, Medizinische Fakultät - Universitätsklinikum Charité, 2003. http://dx.doi.org/10.18452/14984.
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Einleitung: Für die Messung der "Narkosetiefe" werden vorwiegend Parameter des Elektroenzephalogramms (EEG) untersucht, welche offenbar keine Aussage zur Unterdrückung von Bewegungen auf Schmerzreize treffen können. Dies ist auch wenig verwunderlich, da Untersuchungen an Tieren die Ausschaltung einer Bewegung auf Schmerzreiz durch Anästhetika auf der spinalen Ebene erwarten lassen. Der spinale H-Reflex, ein elektrisch ausgelöster, monosynaptischer Reflex, wurde bereits zur Überwachung der Unterdrückung von Bewegungen während der Narkose vorgeschlagen. Diese Arbeit diente der vergleichenden Untersuchung der H-Reflex-Amplitude mit EEG-Parametern unter Sevofluran-Narkosen. Es wurden Konzentrations-Wirkungs-Kurven ermittelt, sowie die Eignung als Parameter zur Vorhersage von Bewegungen auf schmerzhafte Reize überprüft. Weiterhin sollte der Effekt des schmerzhaften Reizes auf die H-Reflex-Amplitude selbst aufgeklärt werden. Methodik: Nach Zustimmung der Ethikkommission und schriftlicher Einwilligung wurden 28 Patientinnen in die Studie eingeschlossen. Sie wurden präoperativ untersucht. Nach anfänglicher Vertiefung bis zur Toleranz einer Larynxmaske, wurde die Narkose mit Hilfe der "up-and-down"-Methode auf einen Wert nahe der minimalen alveolären Konzentration (MAC) eingestellt. Nach mindestens 15 Minuten konstanter Konzentration wurde von einem "steady-state" ausgegangen und am volaren Unterarm ein elektrisch ausgelöster Schmerzreiz (Tetanus-Reiz, 60 mA) appliziert. Für die Ermittlung der Konzentrations-Wirkungs-Kurve diente ein pharmakokinetisch-pharmadynamisches Modell, welches auf einem sigmoidalen Emax-Modell beruht. Die Eignung eine Bewegung vorherzusagen wurde anhand der "Prediction Probability" (PK-Wert) überprüft. Ergebnisse: Bei 14 Patientinnen konnte der H-Reflex kontinuierlich über die gesamte Messperiode ausgelöst werden. Die Wachwerte betrugen für die H-Reflex-Amplituden 6,5 (+/- 4,1 SD) mV. Sevofluran unterdrückt die H-Reflex-Amplituden konzentrationsabhängig. Die Unterdrückung konnte gut durch das sigmoidale Modell dargestellt werden (Median - r^2 = 0,96). Die Unterdrückung der H-Reflex-Amplitude unterliegt einer signifikant steileren Konzentrations-Wirkungs-Beziehung als die der EEG-Parameter spektrale Eckfrequenz 95 (SEF95) und bispektraler Index (BIS). Die H-Reflex-Amplitude konnte Bewegungen auf einen Schmerzreiz mit einer PK von 0,74 vorhersagen, während mittels der EEG-Parameter SEF95 und BIS lediglich zufällige Aussagen bezüglich stattfindender Bewegungen getroffen werden können. Der Schmerzreiz veränderte die H-Reflex-Amplitude, das spontane frontale Elektromyogramm und die Herzfrequenz, nicht jedoch die kortikal abgeleiteten Parameter BIS und SEF95. Schlussfolgerung: Aus dieser Arbeit ergeben sich Hinweise, dass die Unterdrückung von Bewegungen auf schmerzhafte Reize und die Unterdrückung der H-Reflex-Amplitude durch Sevofluran eng verknüpft sind. Auch wenn kein kausaler Zusammenhang besteht, so würde dies die hohe Vorhersagekraft der H-Reflex-Amplituden für Bewegungen auf Schmerzreiz erklären. Sie ist zur Überwachung der Unterdrückung von groben gezielten Bewegungen während einer Narkose geeignet. Mittels H-Reflex-Amplituden können Aktivierungen des Rückenmarkes registriert werden, welche auf kortikaler Ebene nicht sichtbar werden. Zukünftige auf dem H-Reflex basierende Studien können weitere Einsichten in die Mechanismen der Anästhesie liefern und behilflich an der Erarbeitung von Richtlinien zur optimalen Medikamentendosierung sein.<br>Introduction: The measurement of "depth of anesthesia" is mostly done by parameters of the electroencephalogram (EEG), which can not make a statement about the suppression of movement due to painful stimulation. This is not surprising, looking at recent animal studies that assume the anesthetic induced unresponsiveness to noxious stimulation at the side of the spinal cord. The spinal H-reflex, an electric induced, monosynaptical reflex has been proposed to monitor the suppression of movements during anesthesia. This dissertation shows a comparative examination of the H-reflex-amplitude and parameters of the EEG under anesthesia with sevoflurane. Concentration-response functions have been determined, the prediction of movement to painful stimulation has been tested. Also the effect of the painful stimulus itself on the H-reflex-amplitude has been discovered. Methods: After approval of the institutional review board and informed consent were obtained, 28 patients were included into this study. The examination has been done prior to surgery. After induction of anesthesia until a laryngeal mask was tolerated, sevoflurane was decreased to a level close to minimum alveolar concentration (MAC) using the "up-and-down" method. After at least 15 minutes of constant sevoflurane concentration a "steady-state" was assumed and a painful electrical stimulation (tetanic stimulus of 60mA) was applied. The concentration-response functions were determined using pharmacokinetic and pharmacodynamic modeling, based on a sigmoid Emax model. To estimate and compare the predictive value of the parameters, prediction probability Pk was calculated. Results: On 14 patients the H-reflex could been measured continuously throughout the study period. At awake level, H-reflexes had a mean amplitude of 6,5 (+/- 4,1 SD) mV. Sevoflurane depresses the H-reflex-amplitude in a concentration dependent way, which was well modeled by the sigmoid Emax model (median r^2 = 0,96). The depression of the H-reflex-amplitude underlies a significant steeper concentration-response function as the EEG-parameters spectral edge frequency (SEF95) and bispectral index (BIS). H-reflex-amplitude could predict movement on to painful stimulation with a Pk value of 0,74, whereas EEG-parameters could only make statements, concering upcoming movements, by chance. The painful stimulation changed H-reflex-amplitude, frontal recorded electromyogram and heart-frequency but not the cortical recorded parameters BIS and SEF95. Conclusions: Results indicate that the suppression of movement and the suppression of the H-reflex-amplitude caused by sevoflurane are close connected. Although it does not imply a causual connection, it would explain the high predictive value of the H-reflex-amplitude for motor responses to noxious stimuli. H-reflex-amplitude can be used to monitor the suppression of gross purposeful movements during sevoflurane anesthesia. Using H-reflex-amplitude spinal activation can be registered, which are not seen on cortical level. Coming up studies based on the H-reflex can help to get more insights into the mechanisms of anesthesia and help to develop guidelines for optimal drug dosing.
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Zeitouni, Anthony G. "A study of tonic otolithic and neck reflex stimulation on the H-reflex in man." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23952.
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At present, despite considerable interest there is no commonly used clinical test of otolith function. The aim of this study was to develop an otolith test which could be used in a clinical setting. Otolith stimulation was provided by Y-axis static head yawing while the subject was supine. Modulation of the H-reflex recruitment ratio was measured. Ten normal subjects and five patients who had suffered an acute vestibular lesion were tested. Since this rotation involved otolith and neck inputs, a control experiment assessed the contribution of neck inputs separately. Neither otolith and neck inputs combined nor neck inputs alone had a demonstrable effect on alpha motorneuron pool excitability. These observations contradict results in the literature. However, there exist important differences between this study and those in the literature. The findings reported here should motivate further work into the effects of otolith and neck inputs on lumbar motorneurons.
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McGarry, James Timothy. "On the nature of stopping a voluntary action." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0025/NQ38942.pdf.
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Pedão, Sabrina Tiago. "Efeitos de diferentes freqüências e amplitudes de vibração unilateral do tendão calcâneo na orientação postural e no reflexo H em humanos." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/47/47135/tde-16042010-104819/.
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Uma vibração aplicada a um tendão muscular aumenta a freqüência de disparos de aferentes, como os de fusos neuromusculares Ia e II, cujas terminações afetam circuitos da medula espinhal e com isto podem influenciar o controle motor. O objetivo deste estudo foi analisar o efeito de vibrações a duas freqüências (15 e 80Hz) e amplitudes de 1 e 2,5mm aplicadas ao tendão calcâneo direito sobre o sistema de controle postural e sobre a circuitaria neural associada a reflexos monosinápticos da perna. A hipótese era de que a vibração de alta freqüência ativasse preferencialmente os aferentes de fuso neuromuscular de tipo Ia enquanto a vibração a 15 Hz ativasse preferencialmente os aferentes de tipo II. Isto significaria que a vibração a 80 Hz teria forte efeito sobre o reflexo H, enquanto a vibração a 15 Hz teria um efeito significativo sobre a postura. Participaram deste estudo 14 sujeitos sãos. Na postura ereta quieta, foi realizada a aquisição do reflexo H enquanto o tendão calcâneo era vibrado. Após um intervalo de descanso, foi realizada a aquisição do Centro de Pressão (COP) tanto na direção Ântero-Posterior (AP) quanto na Médio-Lateral (ML) em paralelo à aquisição bilateral do EMG dos músculos (SO, TA, GL e GM) nas três condições (antes, durante e após a vibração do tendão calcâneo). Para os estímulos de 1 e 2,5mm realizados a 80 Hz as diferenças foram significativas em relação a todas as variáveis quando comparadas nas três condições, com exceção apenas do DP do TA e GM e, do valor médio do COP ML a 1mm. Em relação à freqüência de 15 Hz, notou-se que não houve diferenças significativas tanto no COP AP e ML quanto no DP do EMG dos músculos da perna esquerda entre as três condições. Quanto aos dados referentes ao DP dos músculos analisados na perna direita, os resultados mostraram que não houve efeitos significativos tanto ao utilizar 15Hz como 80Hz em todas as três condições. Em geral, estes dados mostraram que durante um estímulo vibratório mais forte o COP deslocouse mais para a direção posterior e lateral esquerda do sujeito. E, após interromper o estímulo, em alguns casos o COP ainda mostrava uma alteração prolongada. Em relação à amplitude média do reflexo H, para as amplitudes de vibração de 1 e 2,5 mm a 15 e 80 Hz, as análises apontaram que durante a vibração houve uma forte redução na amplitude do reflexo, sendo que em alguns casos ainda permaneceram reduzidas na condição pós-vibratória. Os resultados mostram que a vibração aplicada ao tendão calcâneo pode ser um forte estímulo à medula e capaz de alterar o controle postural, dependendo de suas características, uma vez que, com parâmetros apropriados, induziu alterações imediatas nos resultados do reflexo H, do COP e do EMG (p.e.). Porém, as alterações a vibrações aplicadas de modo a ativar seletivamente as fibras aferentes do grupo Ia e II mostraram efeitos diferenciais. Vibrações a 80Hz de frequência e a 1 e 2,5mm foram as que mais causaram alterações. A significativa ação sobre o reflexo H é compatível com o aumento da frequência de disparos dos aferentes Ia. Entretanto a forte ação sobre o COP dessas vibrações a 80 Hz sugere que os aferentes Ia podem ter uma importância maior do que a literatura recente tem preconizado, pelo menos para correções a perturbações posturais, uma vez que pode-se supor que a 80 Hz e 1 mm de amplitude os aferentes tipo II são pouco ativados. Por outro lado, a vibração a 15 Hz teve um efeito signficativo sobre o reflexo H mas sem afetar o COP, o que sugere que esta frequência consegue ativar a via Ia, causando depressão homossináptica e/ou inibição pré-sináptica dos aferentes Ia, mas sem chegar a influir no COP de forma significativa. Os resultados são interessantes do ponto de vista de aplicações em potencial para áreas como fisioterapia e reabilitação de pessoas com alterações posturais na clínica. Adicionalmente, abrem novas questões quanto às interpretações fisiológicas de vibrações a diferentes freqüências sobre o tendão calcâneo.<br>A vibration applied to a muscle tendon increases the firing frequency of afferents of types Ia and II innervating muscle spindles, and hence affects the spinal cord circuits and this can affect motor control. The aim of this study was to analyze the effect of vibrations of two frequencies (15 and 80Hz) and two amplitudes (1 and 2.5 mm) applied to the right Achilles tendon on the standing posture and on the H reflex. The hypothesis was that the high frequency vibration activates preferentially the Ia axons while the 15 Hz vibration activates preferentially the type II axons and hence the 80 Hz vibration would have a strong effect on the H reflex and the 15 Hz vibration would have a strong effect on posture. Fourteen subjects participated in this study. Their H reflex was acquired in the upright position while their Achilles tendon was vibrated. After an interval of rest, the center of pressure (COP) signal was acquired for both the antero-posterior (AP) and the medio-lateral (ML) directions in parallel with the acquisition of bilateral electromyograms (EMG) (SO, TA, and GL GM) in the three conditions (before, during and after the vibration of the Achilles tendon). For 1 and 2.5 mm vibrations at 80 Hz the differences were significant for all variables compared in the three conditions, except for the standard deviation (SD) of the TA and GM EMGs and the average value of COP ML for 1mm vibration. For the 15 Hz vibration, there were no significant differences in both the AP and ML COP and SD of the EMG of the left leg in the three conditions. The results for the EMG SD of the right leg showed no significant effects when using both 15Hz and 80Hz in all three conditions. These data showed that during a stronger vibratory stimulus the COP shifted more to the posterior direction and the left side of the subject. And, after stopping the stimulus, in some cases, the COP had not returned to the initial position. In relation to the mean H reflex amplitude for 1 and 2.5 mm vibrations at 15 and 80 Hz, the analysis showed that during vibration there was a stronger reduction in the amplitude of the H reflex, and in some cases the amplitude remained reduced in the post-vibratory period. The results showed that the vibration applied to the Achilles tendon can be a powerful stimulus to the spinal cord and capable of altering the postural control. The effects depended on the vibration features, since, with appropriate parameters, it led to immediate changes in the results of the H reflex, the COP and left leg EMG. However, 80 Hz vibration (1 and 2.5 mm) was the one that caused the largest changes both on COP and H reflex amplitude. The significant action on the H reflex is consistent with the increased frequency of firing of Ia afferent. However the strong action on the COP of vibrations at 80 Hz suggests that the Ia afferents may have a greater importance than what the recent literature has suggested, at least for postural corrections to disturbances, since it can be assumed that the type II afferents are little activated at 80 Hz and 1 mm amplitude. Furthermore, vibration at 15 Hz had a significant effect on the H reflex without affecting the COP, suggesting that vibrations at this frequency can activate Ia afferents, causing homosynaptic depression and / or presynaptic inhibition of Ia afferents, but without influencing the COP significantly. The results are interesting from the standpoint of potential applications to areas such as physical therapy and rehabilitation of patients in the clinic. Additionally, they raise new questions about the physiological mechanisms behind vibratory stimuli applied at different frequencies on the Achilles tendon.
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Grünewald, Matthias Lars. "Einfluss des Anästhetikuns Sevofluran und schmerzhafter Stimuli auf den H-Reflex." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=970059256.
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O'Connor, Susan. "How ageing affects identification of the H-reflex in human masseter /." Title page and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09SB/09sbo18.pdf.
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Cameron, Shawn P. "Focal Wrist Cooling Does Not Alter Indices of Spinal Excitability in the Flexor Carpi Radialis Muscle." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1306953575.
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Riedo, Roger. "Origin of the specific H reflex facilitation preceding a voluntary movement in man /." [S.l : s.n.], 1985. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Martins, Emerson Fachin. "Atividade preparatória de circuitos neuronais medulares durante expectativa para contração muscular voluntária." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/47/47135/tde-27052008-104200/.
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Antecedendo movimentos voluntariamente gerados, existe atividade neuronal encefálica que se inicia alguns segundos antes da execução deste movimento. Esta atividade preparatória é responsável pela elaboração de um plano de execução que alcança a via final comum para realização de um ato motor voluntário, os motoneurônios. Entretanto, na última década, evidências apontam para a participação de circuitos neuronais na medula espinhal apresentando padrão de atividade similar aos padrões observados em áreas encefálicas e que, possivelmente, estaria relacionado a uma atividade preparatória para o movimento voluntariamente gerado. Por este motivo, o presente trabalho teve por objetivo verificar a atividade de circuitos neuronais na medula espinhal durante diferentes instantes de proximidade da ação voluntariamente gerada em paradigma de tarefa motora com período de instrução. Para isso, inicialmente, 15 sujeitos saudáveis, sem histórico de doença neuromuscular foram submetidos ao protocolo experimental. O protocolo experimental constituiu-se do processo de recrutamento dos sujeitos, sua preparação para o ensaio dentro do ambiente experimental, bem como as orientações necessárias para execução dos procedimentos e paradigmas. Os procedimentos referem-se às etapas realizadas para captação do reflexo H, bem como desta captação sob a influência de técnica de condicionamento por inibição pré-sináptica. Essa captação ocorreu em janelas de aquisição em que o sujeito encontrava-se em repouso e em três instantes de expectativa para a execução de ação voluntária, estando o músculo sóleo atuando como agonista (flexão plantar) ou antagonista (dorsiflexão), em paradigma de tarefa motora voluntária com período de instrução. Após os registros, por meio de processamento dos sinais coletados, foi possível se calcular a amplitude pico-a-pico do reflexo H nas diferentes condições experimentais de proximidade da execução (1000, 600 e 200 milissegundos) e de atuação do músculo sóleo (agonista e antagonista) que foi usado para: (1) análise da variação da excitabilidade reflexa, em porcentagem da onda M máxima, (2) análise da ocorrência de inibição pré-sináptica e (3) análise da variação da inibição pré-sináptica, em porcentagem de inibição. Os resultados mostram que a porcentagem da onda M máxima aumentou significativamente nos três instantes de proximidade com os sujeitos estando em expectativa da execução da tarefa motora quando o músculo sóleo atuaria como agonista da contração, quando comparados com os registros obtidos nas mesmas condições em repouso. Contudo, somente a 200 ms da execução é que foi observado aumento da porcentagem da onda M máxima quando o músculo sóleo atuaria como antagonista. Inibição pré-sináptica ocorreu em todas as condições experimentais, contudo aumento significativo da porcentagem de inibição pré-sináptica foi somente observado a 200 ms da execução da tarefa motora em que o músculo sóleo atuaria como antagonista. Diferenças entre agonista e antagonista com relação ao padrão de excitabilidade reflexa foi somente observado a 600 ms de proximidade da execução da tarefa e essas diferenças com relação à porcentagem de inibição pré-sináptica foi somente detectada a 200 ms. Nossos resultados nos permitem concluir que circuitos neuronais na medula espinhal apresentam atividade no período preparatório para a execução de tarefa motora voluntária que podem estar relacionadas ao comportamento de expectativa da realização de uma ação motora eminente, bem como relacionada ao planejamento motor para a ação a longa proximidade da execução de movimentos.<br>There is brain activity preceding voluntary movements a few seconds before the execution of the movement. This preparatory activity is responsible for the execution plan that reaches the final common pathway, i.e., the motoneurons. In the last decade, there have been reports indicating the involvement of spinal cord circuits in the preparatory activity for movement. The present work has the objective of verifying the activity of spinal cord neuronal circuits at different times preceding a voluntary action, under an instructed delay period paradigm. Fifteen healthy subjects participated in the study. The protocol included an explanation of the experimental tasks. Electrophysiological recordings of the H reflex with and without presynaptic inhibition conditioning were employed. The epochs of H reflex recording were associated either with a resting period or with one of three pre-action periods. The subject received a cue at an appropriate time about the type of contraction: plantarflexion or dorsiflexion. Peak to peak H reflex values were computed in the control resting period and at 1000 ms, 600 ms and 200 ms before the action. Percent values of H amplitude with respect to maximum M values were computed as well as the level of presynaptic inhibition. The results have shown that the relative H reflex value increased significantly at the three premovement times for the soleus under an agonist contraction (i.e., plantarflexion) when compared to control. However, when the soleus was an antagonist to the contraction (i.e., dorsiflexion) there was a statistical difference in the H amplitude only at 200 ms before movement. Presynaptic inhibition occurred in all experimental conditions, however only at 200 ms before contraction there was a significant increase. Differences in reflex excitability between agonist and antagonist activity were only observed at 600 ms before action. On the other hand, differences in presynaptic inhibition were only found at 200 ms before contraction. The results indicated that spinal cord neuronal circuits are activated during the preparatory period preceding a voluntary action. These may be correlated with an expectancy behavior for the execution of an imminent motor action and also with the planning of a motor action at larger times preceding movement execution.
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Fornari, Maria Carolina dos Santos. "Padrão eletromiográfico de membros inferiores em resposta a perturbações posturais." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/47/47135/tde-03042009-104150/.
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A manutenção do equilíbrio depende da ativação sinérgica de músculos dos dois hemicorpos, e há evidências de que essa coordenação é mediada por circuitos medulares, que estão sob controle supra-segmentar. O objetivo desse trabalho é descrever mecanismos neurofisiológicos e biomecânicos envolvidos no controle postural de sujeitos saudáveis frente a uma perturbação provocada por uma contração reflexa, enfatizando-se os mecanismos associados à coordenação entre membros. A perturbação postural ocorreu em resposta a um estímulo elétrico unilateral no nervo tibial. Devido a restrições em estudos anteriores, utilizou-se uma ampla abordagem (múltiplos músculos, reflexos cruzados) e estimulação precisamente controlada. Os resultados mostraram um complexo padrão de ativação dos músculos dos membros inferiores bilateralmente. Logo após o estímulo, foram encontradas respostas de curta e média latência em músculos da perna e da coxa. Posteriormente, foram observadas algumas ações musculares de longa latência nos músculos mais distais, que provavelmente foram ativadas em resposta às oscilações posturais. As respostas musculares iniciais sugerem que as informações aferentes e os reflexos medulares possuem uma função muito importante na regulação da coordenação entre membros, durante a manutenção da postura ereta quieta.<br>Balance depends on the synergic activation of muscles bilaterally, and there is evidence that this coordination is mediated by spinal circuits, which are under supra-spinal control. The objective of this study is to describe neurophysiologic and biomechanical mechanisms involved in the postural control of healthy subjects submitted to a disturbance provoked by a muscular reflex contraction. The postural perturbation was caused by a unilateral electric stimulation to the popliteal fossa. The analysis emphasizes the mechanisms associated with interlimb coordination. In this work, methodological approaches expanded those of previous work, the recordings being done bilaterally and the stimulus being precisely controlled. The results showed a complex pattern of bilateral muscular activation. Short and medium latency responses were found in the leg and thigh muscles. These were followed by some muscular activity at longer latencies, probably occurring due to the postural oscillations. The initial muscular responses suggest that the afferent inflow and the spinal cord reflexes have an important function in the between-limb coordination during the standing posture.
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Manella, Kathleen J. "Operant Conditioning of Tibialis Anterior and Soleus H-reflex Improves Spinal Reflex Modulation and Walking Function in Individuals with Motor-Incomplete Spinal Cord Injury." Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_dissertations/679.
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Spinal cord injury (SCI) manifests signs of spasticity, plantar flexor (PF) hyperreflexia and ankle clonus, and deficits in motor function. In individuals with motor-incomplete SCI (MISCI), ankle clonus may limit independent walking function. Ankle clonus is attributed to enhanced soleus stretch reflex (SSR) excitability due to decreased supraspinal input and maladaptive reorganization of spinal reflex circuitry. We explored these questions: 1. What are the biomechanical, clinical, and neurophysiologic correlates of ankle clonus? 2. Does locomotor training improve ankle clonus and walking function? 3. Will operant conditioning-based interventions that increase tibialis anterior activation or decrease soleus reflex excitability improve ankle motor control and walking function? In Chapter 2 we compared Ankle Clonus Drop Test (Drop Test) measures with clinical and neurophysiologic measures. Drop Test measures were highly reliable and exhibited moderate to strong correlations with clinical and neurophysiologic measures. Analysis of EMG activity during clonus revealed a predominant pattern of antagonist coactivation. In Chapter 3 we investigated the effects of locomotor training on PF and quadriceps spasticity, and walking function. We assessed responsiveness of the PF reflex threshold angle, a Drop Test measure of PF spasticity. PF and quadriceps spasticity decreased after locomotor training and were moderately correlated with increased walking speed. The PF reflex threshold angle measure discriminated between individuals with and without clonus. In Chapter 4 we compared the effects of two operant-conditioning based interventions to, (1) increase TA EMG activation (TA↑) and (2) decrease SOL H-reflex amplitude during active dorsiflexion (SOL↓), on reflex modulation, ankle motor control, and walking function. Each intervention improved walking function; however, modulated the variables in unique ways. TA↑ improved deficits of strength and range of motion, and SOL↓ improved modulation of SSR and SOL/TA coactivation. In Chapter 5 we discussed implications of our conclusions: (1) Drop Test ankle clonus measures are valid, reliable, and responsive; (2) antagonist coactivation was predominant during ankle clonus; (3) in individuals with chronic MISCI, locomotor training decreased PF and quadriceps spasticity and improved walking function; and (4) an operant conditioning-based intervention to either increase TA strength or decrease SOL reflex excitability improved spinal reflex modulation and walking function.
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Richter, Julia [Verfasser], and H. O. [Akademischer Betreuer] Handwerker. "Der Einfluss von Sympathicotomie auf elektrisch induziertes Axon Reflex Schwitzen und Axon Reflex Flare bei Patienten mit Hyperhidrose / Julia Richter. Betreuer: H. O. Handwerker." Erlangen : Universitätsbibliothek der Universität Erlangen-Nürnberg, 2011. http://d-nb.info/1015782582/34.
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Chen, Yi. "Re-educating the injured spinal cord by operant conditioning of a reflex pathway." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1147873519.
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Johannsson, Johanna. "AGE-RELATED NEURO-MECHANICAL CHANGE DURING STAIR LOCOMOTION." Doctoral thesis, Universite Libre de Bruxelles, 2018. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/277650.
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Stair locomotion is one of the most difficult and challenging type of locomotion for older adults, with a high risk of fall and injuries. A major reason is that the neuromuscular system undergoes various changes through the aging process. The aim of this doctoral thesis is to study the age-related neuro-mechanical adjustments associated with stair locomotion and more specifically to investigate the interaction between neural and muscular changes in the plantarflexor muscles. To that aim, three main projects have been performed. The first two projects investigated the influence of age on spinal and supraspinal excitability when individuals stood at the bottom and the top of a 3-steps staircase and spinal excitability during stair locomotion. The third one focused on the age-related influence on the muscle-tendon behavior during stair locomotion. The result of the first project indicate a lower dependence on spinal pathway to control soleus motoneurons with a similar change observed in both age groups suggesting that healthy older adults preserved their ability to adjust postural control to environmental demands. The second project is the first to report the modulation of H-reflex amplitude in the plantarflexor muscles during stair ascent and descent in healthy young and older adults. This modulation likely reflects an increased role of descending inputs in controlling plantarflexor muscle activation during the stair gait cycle. However, similarly to the first project the modulation of the net excitatory inputs from group I afferents during the stair gait cycle does not seem to be influenced by healthy aging. The third project suggest that length changes of the Achilles tendon and lateral gastrocnemius (LG) fascicles favour the storage and recovery the tendon elastic strain energy over the muscle work, improving thereby the mechanical efficiency of stair ascent in young adults. In older adults, it seems that a different behavior is used to maintain a mechanical efficiency during stair ascent. In contrast, during stair descent, no difference was observed between age groups regarding the LG muscle-complex behavior despite some kinematics changes. In conclusion, this doctoral thesis indicates that despite some age-related structural and functional changes of the neuromuscular system, similar neural modulations occur during stair locomotion in young and healthy older adults. During stair ascent, a similar global pattern of change in length for the fascicle’s length and the modulation of the H reflex can be observed. However, during stair descent, H reflex modulation cannot be simply explained by the pattern of muscle length change.<br>Doctorat en Sciences de la motricité<br>info:eu-repo/semantics/nonPublished
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Tucker, Kylie. "Methodological considerations and the effect of pain on the H-reflex and maximal M-wave in the human triceps surae." Click here to access, 2006. http://thesis.library.adelaide.edu.au/public/adt-SUA20060704.165047/index.html.
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Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, Discipline of Physiology, 2006.<br>Includes author's previously published papers. "June 2006" Includes bibliographical references. Also available in a print form.
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Martins, F?bio de Lima. "Efeitos imediatos da eletroestimula??o nervosa transcut?nea e crioterapia na espasticidade e na atividade eletromiogr?fica de sujeitos hemipar?ticos." Universidade Federal do Rio Grande do Norte, 2009. http://repositorio.ufrn.br:8080/jspui/handle/123456789/16678.
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Previous issue date: 2009-10-29<br>Funda??o de Amparo a Pesquisa do Estado de S?o Paulo<br>Cerebrovascular accident (CVA) is a term used to characterize an ischemic or hemorrhagic vascular injury, which has got as main clinic manifestations, the motor and reflex function disturbance. In the first stage there is flaccidity and loss of voluntary movements that afterwards is substituted by mass patterns and spasticity. The spasticity brings with itself functional deficits and can generate negative impacts in various motor patterns. The aim of this research was to investigate the hyperreflexia and identify the immediate effects of transcutaneous nervous stimulation (TENS) and cryotherapy in the spasticity and electromyographic activity of hemiparetic subjects. The study is characterized as an almost experimental type, in which were selected, to compose the sample, 16 patients of both sex with CVA sequel. These individuals were evaluated by collecting the amplitude peak to peak and H reflex latency, Motor response (M response) in solear muscle and the
electromyography (EMG) of the injured and healthy legs anterior tibial muscles. In the injured limb the evaluations occurred in different days for cryotherapy, TENS and control, in two
moments, before and after the interventions. The healthy limb was evaluated one single time to serve as baseline, for comparison with the injured limb. It was used an statistic analysis, the t paired student test to identify the H reflex differences, latency and EMG of the injured and healthy limbs and to compare the results before and after the recourses application. The ANOVA for related samples was used to identify the differences among the recourses used. It was attributed for the statistic tests a significance level of 5%. The amplitude peak to peak of normalized maximum H reflex through the maximum motor response (Hmax/Mmax), showed itself significantly increased in the injured limb (p=0.0245). The H reflex latency was presented reduced in the injured limb (p=0, 0375). The electromyographic activity was showed decreased in the injured limb (p< 0.0001). After the TENS there was a Hm?x/Mm?x ratio decrease (0.60?0.16 versus 0.49.?0.18; P = 0.0006). Nonetheless, Just after the cryotherapy application there was an increase of Hm?x/Mm?x ratio (0.58 ? 0,15 to 0.77 ? 0.13, P=0,0007) and increase of signal latency (30.41 ? 1.87 versus 33.24 ? 2.19; P=0.0001). The electromyographic activity wasn t altered significantly by any resource. It was met statistic significant differences when the Hm?x/Mm?x P<0.0001) ratio and H reflex latency (P<0.0001) were compared between the post TENS, cryotherapy and control. One can conclude that the TENS can be used to spasticity immediate reduction, and that the cryotherapy can increase the hyperreflexia state in spastic patients. Nonetheless, the spasticity decrease or increase didn t provoke lectromyographic activity change in the muscle that is opponent to the spastic one<br>Acidente Vascular Encef?lico (AVE) ? o termo empregado para caracterizar uma les?o vascular isqu?mica ou hemorr?gica, que tem como principais manifesta??es cl?nicas, o dist?rbio da fun??o motora e reflexa. No est?gio inicial h? presen?a de flacidez e falta de movimentos volunt?rios, que posteriormente ? substitu?do por padr?es em massa e espasticidade. A espasticidade traz consigo d?ficits funcionais e pode gerar impactos negativos em diversos padr?es motores. O objetivo da pesquisa foi investigar os efeitos imediatos da eletroestimula??o nervosa transcut?nea (TENS) e crioterapia na espasticidade
e na atividade eletromiogr?fica de sujeitos hemipar?ticos. O estudo caracteriza-se por ser do tipo quase experimental, no qual foram selecionados para compor a amostra, 16 pacientes
de ambos os sexos com sequela de AVE. Estes indiv?duos foram avaliados captando-se a amplitude pico a pico e lat?ncia do reflexo H, resposta Motora (resposta M) no m?sculo solear e o eletromiograma (EMG) do m?sculo tibial anterior do membro comprometido e n?o comprometido. No membro comprometido as avalia??es ocorreram em dias diferentes para crioterapia TENS e controle, em dois momentos, antes e depois das interven??es. O membro n?o comprometido foi avaliado uma ?nica vez para servir como linha de base, para compara??o com o membro comprometido. Utilizou-se na an?lise estat?stica, o test t de student pareado para identificar as diferen?as do reflexo H, lat?ncia e EMG do membro comprometido e n?o comprometido e para comparar os resultados antes e depois da
aplica??o dos recursos. A ANOVA para amostras relacionadas foi utilizada para identificar as diferen?as entre os recursos utilizados. Atribuiu-se para os testes estat?sticos o n?vel de
signific?ncia de 5%. A amplitude pico a pico do reflexo H m?ximo normalizado pela resposta motora m?xima (Hm?x/Mm?x), mostrou-se significativamente aumentada no membro comprometido (p=0.0245). A lat?ncia do reflexo H reduziu no membro comprometido, com essa redu??o sendo estatisticamente significativa (p=0,0375). A atividade eletromiogr?fica se mostrou diminu?da no membro comprometido (p< 0.0001). Depois da TENS houve uma diminui??o da rela??o Hm?x/Mm?x (0.60?0.16 versus 0.49.?0.18; P = 0.0006). No entanto, logo ap?s a aplica??o do gelo houve um aumento da rela??o Hm?x/Mm?x (0.58 ? 0,15 para 0.77 ? 0.13, P=0,0007) e aumento da lat?ncia do sinal (30.41 ? 1.87 versus 33.24 ? 2.19;
P=0.0001). A atividade eletromiogr?fica n?o foi alterada significativamente por nenhum recurso. Foram encontradas diferen?as estatisticamente significativas quando a raz?o
Hm?x/Mm?x (P<0.0001) e lat?ncia do reflexo H (P<0.0001) foram comparadas entre o p?s-TENS, P?s- crioterapia e controle. Pode-se concluir que a TENS pode ser utilizada para fins de redu??o imediata da espasticidade, e que a crioterapia pode aumentar o estado de hiperreflexia nos pacientes esp?ticos. Entretanto, a diminui??o ou o aumento da espasticidade n?o ocasionou altera??o na atividade eletromiogr?fica do m?sculo antagonista ao esp?stico
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Motawar, Binal Hortobagyi Tibor. "Modulation of H Reflex in Response to Voluntary Contraction of the Homologous Muscle in the Contralateral Limb." [Greenville, N.C.] : East Carolina University, 2010. http://hdl.handle.net/10342/2716.
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Egawa, Ken'ichi, Yukio Oida, Yoshinori Kitabatake, et al. "Effect of Weight Bearing on the Soleus H-reflex During Upright Standing Under the Head-out Water Immersion Condition in Humans." Research Institute of Environmental Medicine, Nagoya University, 2003. http://hdl.handle.net/2237/7605.
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Nordlund, Maria M. "On spinal mechanisms for reflex control in man : modulation of Ia-afferent excitation with changes in muscle length, activation level and fatigue /." Stockholm, 2004. http://diss.kib.ki.se/2004/91-7349-821-1/.
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Pulverenti, Timothy S. "An investigation of the neurophysiological factors contributing to reductions in muscle force after stretching." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2017. https://ro.ecu.edu.au/theses/2047.
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Acute bouts of prolonged passive muscle stretching are commonly shown to attenuate maximal force production and negatively affect performance of physical tasks. It has become increasingly apparent that a centrally-mediated impaired voluntary neural drive is the primary factor underpinning stretch-induced force loss. Exacerbated stretching-related sensory feedback could acutely decrease motor cortical excitability and thus impair the level of descending cortical drive reaching muscle. On the other hand, weakened neural drive could stem from changes at the spinal level by alterations in the net excitatory and inhibitory afferent feedback to the spinal motoneurons. However, potential contributions of supraspinal and spinal mechanisms to stretchinduced force loss have not been explicitly studied and this impedes our ability to identify methods to overcome the force decrement after acute muscle stretching. Therefore, the overall aim of this research was to investigate the neurophysiological factors contributing to force loss after acute passive plantar flexor muscle stretching, with particular attention to changes in supraspinal and spinal processes. In Study 1, stretch-induced changes in corticospinal excitability (to soleus) were examined using transcranial magnetic stimulation (TMS) at rest and during maximal muscular contractions. In Study 2, the effect of acute passive muscle stretching on facilitatory Ia afferent spinal reflex pathway and corticospinal excitability were examined using electrically evoked Hoffman reflexes and TMS during submaximal (constant EMG) isometric plantar flexions. Finally, the effect of acute stretching on the sensitivity of tendon tap reflexes and the soleus late response elicited by TMS were examined in an effort to assess potential changes in muscle spindle sensitivity. In each study, significant reductions in both maximum voluntary isometric plantar flexion torque (range: -14.3–20.1%) and triceps surae electromyographic activity (-15.9–18.0%) were found after 5 min of plantar flexor stretching (560-s stretches), and changes in these were highly correlated (r = 0.61–0.85). These data were taken as evidence for a stretch-induced impairment in neural drive underpinning the stretch-induced force loss. However, there were no observable stretch-induced changes in motor-evoked potential amplitude (an indicator of intrinsic corticospinal excitability) or duration of the cortical silent period (an indicator of GABAB-mediated intracortical inhibition), measured at rest or during either submaximal or maximal contractions. In addition, synaptic transmission of the Ia afferent spinal reflex pathway was not significantly affected after stretching as there was a lack of change in the Hoffman reflex amplitude. Of interest was that no changes in tendon reflex responses were detected, but the soleus late response was nearly abolished after stretching and had a similar temporal recovery to reductions in neural drive and force. This may indicate an effect of stretch on a cerebellar-mediated postural response. The present data therefore provide no evidence that alterations in corticospinal excitability, GABAB-mediated intracortical inhibition, Ia reflex pathway or muscle spindle sensitivity contribute to the stretch-induced force loss. Nonetheless, loss (immediately post-stretch) and then recovery of the soleus late response may indicate that cerebellar function mediating postural control may be influenced, and this may speculatively be associated with previous reports of modifications of balance and postural sway.
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Müller, Katja. "Untersuchung der Erregbarkeit spinaler Motoneurone während Propofolmononarkosen." Doctoral thesis, Humboldt-Universität zu Berlin, Medizinische Fakultät - Universitätsklinikum Charité, 2006. http://dx.doi.org/10.18452/15423.
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Einleitung: Zur Messung der Narkosetiefe standen bisher vor allem aus dem EEG abgeleitete Parameter im Mittelpunkt der Forschung, die sehr gut geeignet sind, die hypnotische Komponente der Anästhesie abzubilden. Eine Vorhersage auf motorische Reaktionen lassen sie jedoch nicht zu. Eine vorausgehende Studie hat gezeigt, dass unter Sevofluran der spinale H-Reflex mit der chirurgischen Immobilität korreliert. Die vorliegende Studie untersucht, ob motorische Reaktionen während Propofolmononarkosen mittels H-Reflex besser vorausgesagt werden können als mit den EEG-Parametern Bispektraler Index (BIS), spektrale Entropie (SE) und response Entropie (RE). Außerdem wurde der Einfluss von Propofol auf die Erholungskurve des H-Reflexes unter Doppelstimulation untersucht. Methodik: Nach Zustimmung der Ethikkommission und schriftlicher Einwilligung wurden 17 Patienten in die Studie eingeschlossen und ausgewertet. Nach der „up-and-down“-Methode von Dixon wurde die Konzentration von Propofol auf einen Wert eingestellt, bei dem die Hälfte der Patienten auf einen am Unterarm ausgelösten elektrischen Tetanus-Reiz (60 mA) mit einer gezielten motorischen Reaktion reagierten. Nach einer Kontrollmessung wurde die Konzentration von Propofol 15 min konstant gehalten. Danach wurde von einem „steady state“ ausgegangen und der Tetanusreiz wurde ausgelöst. Die Vorhersagefähigkeit der möglichen Narkosetiefe-parameter auf eine Bewegung wurde mit der „Prediction Probability“ (PK-Wert) ermittelt. Im zweiten Teil wurde der H-Reflex anhand der Doppelstimulation mit größer werdenden Interstimulusintervallen (50-8000 ms) untersucht. Ergebnisse: Die Wachwerte für die H-Reflexamplitude liegen bei 5,9 (± 3,8 SD) mV. Der von uns berechnete C50-Tetanus-Wert beträgt 4,5 ± 0,45 mg/l. Die PK-Werte 0,47 für den H-Reflex und 0,45 für die Herzfrequenz lassen nur zufällige Aussagen auf motorische Reaktionen zu. Die EEG-Parameter zeigen höhere PK-Werte: BIS (0,74), SE (0,73), RE (0,71). In diesem Bereich liegt auch der PK-Wert der Propofolzielkonzentration (0,76). Der Schmerzreiz beeinflusste weder die H-Reflexamplitude noch die EEG-Parameter. Bei der Doppelstimulation zeigte sich eine verzögerte Erholung des H-Reflexes unter Doppelstimulation, die am stärksten im Bereich der interkurrenten Fazilitation unter den Interstimulusabständen von 150 und 200 ms. Schlussfolgerung: Für die Vorhersage motorischer Reaktionen während Propofolmono-narkosen sind EEG-Parameter wie BIS, SE und RE etwas besser geeignet als der spinale H-Reflex. Dies steht im Gegensatz zu einer Untersuchung mit Sevofluran und wird auf die unterschiedlichen Wirkmechanismen von volatilen und intravenösen Anästhetika zurückgeführt. Die Unterdrückung der Erholungskurve des H-Reflexes unter Doppelstimula-tion, die vor allem im Bereich der interkurrenten Fazilitation stattfindet, ist möglicherweise durch eine Reduktion supraspinaler exzitatorischer Einflüsse zu erklären.<br>Introduction: The measurement of „depth of anaesthesia“ is mostly done by parameters of the electroencephalogram (EEG) which can predict hypnosis whereas the prediction of immobility is not possible with those parameters. A previous study has shown that the H-reflex amplitude can be used for monitoring of immobility during sevoflurane anaesthesia. This study examined whether the prediction of movement to painful stimulation is also possible during propofol anaesthesia on the basis of the H-reflex-amplitude compared with the EEG-parameters bispectral index (BIS), spectral entropy (SE) and response entropy (RE). Furthermore the influence of propofol on the H-reflex-recovery under double pulse stimulation was tested. Methods: After approval of the institutional review board and informed consent were obtained, 17 patients were included into this study. Using the “up-and down”-method the concentration of propofol was adjusted to the level where half of the patients do not move to painful stimulation (C50-tetanus-value). Propofol was administered after a baseline measurement. After at least 15 minutes of constant propofol concentration a "steady-state" was assumed and a painful electrical stimulation (tetanic stimulus of 60mA) was applied. To estimate and compare the predictive value of the parameters, prediction probability Pk was calculated. The H-reflex during double pulse stimulation was examined with interstimulus intervals ranging from 50 to 8000 ms. Results: At awake level, H-reflexes had a mean amplitude of 5.9 (+/- 3.8 SD) mV. The calculated C50-tetanus-value was 4.5 (+/- 0.45 SD) mg/l. With Pk-values of 0.47 for the H-reflex amplitude and 0.45 for the heart rate the prediction of movements is just by chance. The Pk-values of the EEG-parameters were higher: BIS (0.74), SE (0.73), RE (0.71). At this level was also the Pk-value of the propofol concentration (0.76). The painful stimulation influenced neither the H-reflex amplitude nor the EEG-parameters. The double pulse stimulation showed a delay in the H-reflex-recovery at interstimulus intervals of 150 and 200 ms. Conclusion: The prediction of movement during propofol anaesthesia is better using the EEG-parameters BIS, SE and RE compared to the H-reflex-amplitude. These results are in contrast to a previous study with sevoflurane which can be explained by the different molecular mechanisms of action of volatile and intravenous anaesthetics. The depression of the recovery-curve of the H-reflex under double pulse stimulation is possibly due to the reduction of supraspinal excitatory influences.
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Wallace, Brian Joseph. "MUSCULAR AND NEURAL CONTRIBUTIONS TO POSTACTIVATION POTENTIATION." UKnowledge, 2015. http://uknowledge.uky.edu/khp_etds/21.
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Muscle performance is partially a consequence of its recent contractile history. Postactivation potentiation (PAP) can occur after muscle contractions and leads to enhanced neuromuscular performance. The purpose of this dissertation was to explain the relationship between muscle factors (twitch potentiation, TP) and neural factors (reflex potentiation, RP) contributing to overall PAP following a non-fatiguing volitional muscle contraction. The tibial nerves of fifteen resistance trained volunteers (eleven men, four women) were stimulated intermittently at supramaximal (Mmax) and submaximal (Hmax) intensities for 20 minutes on separate days under three conditions: rest (Control); after a after a 10 second maximum voluntary isometric contraction (MVIC) of the plantarflexors; and after a low frequency fatigue protocol prior to the MVIC. Plantarflexion isometric torque and rate of force development (RFD), and soleus and gastrocnemius EMG Hmax/Mmax ratios, were analyzed. Both experimental conditions resulted in TP at 10 seconds post-MVIC compared to the control condition. The two experimental conditions were not different for any measure. Torque and RFD at Hmax (overall PAP) were highest at 3 and 4.5 minutes post MVIC, respectively, but were not significantly different from the control condition. EMG values generally were insignificantly increased in the experimental conditions versus the control condition. Mmax torque and RFD significantly contributed to Hmax torque and RFD at 20 seconds, Hmax peak, and 20 minute post-MVIC time points. The soleus significantly contributed to Hmax torque at 20 seconds and 20 minutes post-MVIC, and Hmax RFD at 20 seconds, 4.5 minutes, and 20 minutes post-MVIC. The results of this study suggest that both muscle and neural factors play a significant role in overall PAP, and that neural factors may play a more meaningful role in RFD potentiation than torque potentiation.
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Lira, Jumes Leopoldino Oliveira. "Níveis de inibição pré-sináptica durante a iniciação do passo em indivíduos com e sem bloqueio da marcha na doença de Parkinson: um estudo transversal." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/100/100139/tde-26112018-172744/.
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Os objetivos deste estudo foram comparar os níveis de inibição pré-sináptica (IPS) durante a iniciação do passo entre indivíduos com doença de Parkinson (DP) com bloqueio motor (BM), sem-BM (S-BM) e indivíduos saudáveis pareados pela idade (ISPI) e, possíveis correlações entre os níveis de IPS com as variáveis comportamentais (amplitude e tempo do ajuste postural antecipatório [APA]) e os escores do New Freezing of Gait Questionnaire (NFOG-Q). A amostra foi composta por 22 indivíduos com BM e 12 S-BM (estágio 3 da DP avaliados no estado on da medicação). Dezesseis ISPI também foram incluídos no estudo. Todos atenderam os critérios de inclusão. Os indivíduos foram avaliados em dois dias. No primeiro dia, todos responderam uma anamnese e o Mini Exame do Estado Mental. Para os indivíduos com DP foi aplicada a escala de estadiamento da DP e a parte III da Escala Unificada de Avaliação da DP (UPDRS) e somente os indivíduos com BM foram avaliados com o NFOG-Q. No segundo dia, todos os indivíduos realizaram a tarefa iniciação do passo na plataforma de força AMTI para avaliação da amplitude e do tempo do APA com ou sem a evocação do reflexo-H na condição teste ou condicionado. O estimulador portátil Nicolet® Viking Quest da CareFusion foi utilizado para evocar o reflexo-H teste e condicionado. O estímulo elétrico foi evocado quando a amplitude do APA ultrapassasse 10 a 20% da linha de base. Todos indivíduos realizaram a tarefa iniciação do passo em 3 condições: 1) sem estímulo; 2) estímulo teste estimulação no nervo tibial; e 3) estímulo condicionado estimulação do nervo fibular antes (intervalo de 100 ms) da estimulação do nervo tibial. Nas três condições, os indivíduos foram instruídos a realizarem 15 passos, logo, 15 estímulos nas condições 2 e 3 de maneira aleatória. A ANOVA one way mostrou diferenças significantes nos valores de IPS entre os três grupos, onde os ISPI apresentaram valores maiores de IPS do que os outros dois grupos e, indivíduos S-BM apresentaram valores maiores IPS comparado aos indivíduos com BM (P<0,001), porém, todos os indivíduos deste último grupo apresentaram facilitação. Adicionalmente, amplitudes maiores e tempos menores do APA foram observados somente para os ISPI (P<0,05), além disso, não foram observadas diferenças entre essas variáveis para os dois grupos de DP (P>0,05). Em relação às correlações, especialmente para os indivíduos com BM, observamos que valores maiores de facilitação estão: fortemente associados com os escores maiores do NFOG-Q (r = -74; P<0,0001); moderadamente associados com as amplitudes menores do APA (r = 0,54; P<0,004); e fracamente associados com os tempos maiores do APA (r = -0,42; P<0,244). Por fim, houve uma forte associação entre as amplitude menores do APA e escores maiores do NFOG-Q (r = -,075; P<0,0001). Em conclusão, indivíduos com BM apresentam facilitação (ausência de IPS) durante a iniciação do passo e associada com deficiências na amplitude e tempo do APA e a severidade do BM. Isso indica que a medula espinhal tem participação na iniciação do passo e pode ser fortemente influenciada por alterações sensório-motoras<br>The aims of this study were to compare the presynaptic inhibition levels (PSI) in the step initiation between subjects with Parkinson\'s disease (PD) with freezing of gait (FoG), non-FOG (non-FoG), and age-matched healthy controls (HC) and, possible correlations between the PSI levels with the behavioral variables and the New Freezing of Gait Questionnaire (NFOG-Q) scores. Twenty individuals with FoG, 12 individuals with non-FoG (stage 3 of PD assessed in the clinically defined on state), and 16 HC met the inclusion criteria. Subjects visited the laboratory for two days. On the first day, all of the subjects answered the anamnesis and the Mini-Mental State Examination. However, only in the subjects with PD were assessed the severity of disease and the motor symptoms (Unified Parkinson´s Disease Rating Scale part III [UPDRS-III], but the FoG severity was assessed only in the subjects with FoG. On the second day, all of the subjects performed the step initiation on the force platform (AMTI) to assess amplitude and time of anticipatory postural adjustment with or without evoking H-reflex in the test or conditioned condition. The constant-current stimulator (Nicolet® Viking Quest portable EMG apparatus, CareFusion) was used to evoke the H-reflex. The electrical stimulus was evoked when the APA amplitude exceeded 10 to 20% of the baseline. All of the subjects performed the step initiation in 3 conditions: 1) without stimulation of the nerve; 2) test stimulus stimulation of the tibial nerve; and 3) conditioning stimulus - stimulation of the fibular nerve before (100 ms interval) stimulation of the tibial nerve. At three conditions, subjects were instructed to perform 15 steps, thus, 15 stimuli at conditions 2 and 3 in a random order. The ANOVA one way showed significant differences in the PSI values between the three groups, where the ISPI presented higher values of PSI than the other two groups, and S-BM individuals had higher PSI values compared to individuals with BM (P<0.001), however all of the individuals with FoG presented facilitation. In addition, larger amplitudes and smaller times of APA were observed only for ISPI (P<0.05); in addition, no differences were observed between these variables for the two PD groups (P>0.05). In relation to correlations, especially for individuals with FoG, we observed that greater values of facilitation are: strongly associated with the higher NFOG-Q scores (r = -0.74; P<0.0001); moderately associated with the smaller APA amplitudes (r = 0.54; P<0.004); and weakly associated with higher APA times (r = -0.42, P<0.244). Finally, there was a strong association between the smaller APA amplitudes and higher NFOG-Q scores (r = -0.75, P<0.0001). In conclusion, individuals with FoG presented facilitation (absence of PSI) in the step initiation which was associated with deficits in amplitude and time of APA and FoG severity. This indicates that the spinal cord has participation in the step initiation that can be strongly influenced by the abnormal sensory motor
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Mattos, Eugênia Casella Tavares de. "Adaptações neurais na medula espinhal de humanos para diferentes tipos de treinamento físico." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/47/47135/tde-26082009-150531/.
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Introdução:As adaptações neurais ao treinamento físico vêm sendo amplamente estudadas e a medula espinhal é um dos locais de possível adaptação. No entanto nenhuma avaliação longitudinal havia sido feita diretamente sobre as circuitarias inibitórias medulares. Até o presente momento as alterações eram somente suposições. O presente trabalho verificou as circuitarias medulares responsáveis pela inibição recíproca (IR) e inibição pré-sináptica (IPS) em sujeitos submetidos a diferentes treinamentos. Materiais e Métodos: Para o treino aeróbico (resistência) foram avaliados 25 soldados submetidos ao treinamento militar do Exército Militar Brasileiro. Foram feitas 3 avaliações uma pré-treino e outras duas com 3 e 9 meses após o inicio das atividades no ano de 2006. Outros 29 sujeitos foram divididos em 3 grupos: controle (permaneceram 8 semanas sem atividades de reinamento), grupo de treino de força máxima e treino de potência. Eles foram submetidos a 8 semanas de treino, realizado com séries de agachamento livre com peso. Para avaliação das circuitarias medulares foi utilizado o reflexo H do sóleus condicionado com estímulos no nervo fibular comum (NFC) - que inerva o músculo tibial anterior (TA). O intervalo entre o estímulo condicionante e o estímulo teste determinou a avaliação da IR, da inibição D1 e da inibição D2 (IPS). Outras variáveis também foram calculadas como: contração voluntária máxima isométrica (CVM) do sóleus e TA e seus respectivos eletromiogramas (EMG), relação elétrica e mecânica entre Hmax/Mmax e condicionamento do EMG do sóleus por estímulos no NFC. Foram feitas análises pareadas com teste t-student para o grupo militar e ANOVA two-way para comparação dos grupos de força máxima e potência com o grupo controle. Principais Resultados: O grupo do exército apresentou aumento na força do sóleus e do TA, juntamente com aumento no RMS do EMG do sóleus e do torque gerado pela onda Mmax, sem alterações nos relações Hmax/Mmax. O treinamento militar reduziu significativamente a inibição D1 e mostrou tendências a aumento da IPS. O grupo de força máxima não mostrou aumento de força isométrica, no entanto apresentou aumento na relação elétrica Hmax/Mmax, com concomitante redução da IR e aumento da IPS. O grupo de potência mostrou ganho na força máxima isométrica somente do sóleus. A capacidade de gerar torque reflexamente também aumentou neste grupo, com aumento significativo na relação mecânica Hmax/Mmax. Esta melhora na utilização do arco reflexo também foi verificada com redução da IPS e aumento da IR neste grupo.Conclusões: Estes resultados mostraram que a medula espinal sofre plasticidade nas vias inibitórias IR, inibição D1 e D2, e que esta plasticidade é dependente do tipo de tarefa realizada.<br>Introduction: Neural adaptations with physical training have been widely studied. The spinal cord is a possible locus of adaptation. However, longitudinal studies that evaluate directly the spinal cord pathways have not been found in the literature. Therefore, all reports from the literature justify changes found in measured responses to exercise by hypotheses on spinal cord mechanisms. This study had the objective of measuring features of specific spinal cord pathways to check if they change according to the type of physical training. The pathways related to reciprocal inhibition (RI) and pre-synaptic inhibition (PSI) were investigated in subjects undergoing different trainings. Materials and Methods: For endurance training 25 soldiers were subjected to military training of the Brazilian Army. Evaluations were made three times, one previous to the beginning of the activity and twice post-training (within 3 and 9 months). Other 29 subjects were divided into: control group (with no training), maximal strength group and power group. They were subjected to 8 weeks of training with series of squat movements. The soleus H reflex conditioning with stimuli in the common peroneal nerve (CPN) was used to evaluate the spinal cord pathways. The interval between the conditioning and the test stimulus determine the assessment of RI, D1 inhibition and D2 inhibition (PSI). Other variables were also calculated: maximum voluntary isometric contraction from soleus and tibialis anterior and their electromyograms (EMG), electrical and mechanical Hmax/Mmax ratio and 3 inhibitions over the soleus EMG conditioned by stimuli to the CPN. The results were analyzed with paired t-student test for the military group and with two-way ANOVA to compare the maximal strength and power groups with the control group. Main Results: The military group had increased strength of the soleus and the TA muscles, with an increase in the RMS of the soleus EMG. This group also increased the torque generated by the Mmax-wave, without changes in Hmax/Mmax ratio. The military training significantly reduced D1 inhibition and showed tendencies to increase the PSI. The maximal strength group showed no differences in isometric strength, but had increased Hmax/Mmax ratio with concomitant reduction of RI and increased PSI. The power group increased isometric strength only for the soleus muscle. This group also improved the ability to generate torque by reflex pathways, with significant increase in the mechanical Hmax/Mmax ratio, with a reduction of PSI and increase of RI. Conclusions: These results show that spinal cord plasticity occurs in the inhibitory pathways of reciprocal inhibition, D1 inhibition and D2 inhibition (pre-synaptic inhibition), and that plasticity is dependent on the type of trained movement.
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Barrue-Belou, Simon. "Contrôle nerveux de la contraction volontaire excentrique chez l'homme : approche neurophysiologique et plasticité à l'entraînement." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30201/document.
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L'objectif de ce travail de thèse est d'étudier d'une part les spécificités de la commande nerveuse lors de la contraction excentrique en explorant les mécanismes impliqués au niveau spinal et d'autre part d'examiner les mécanismes nerveux responsables de la plasticité du système neuromusculaire après un entraînement de force excentrique sous-maximal. A travers ce travail de thèse, nous mettons en évidence la contribution de l'inhibition récurrente à la réduction de l'activation musculaire classiquement observée lors de la contraction excentrique. Par ailleurs, nous montrons que l'inhibition récurrente est majorée lors des contractions sous-maximales indépendamment du mode de contraction. Ces résultats soulignent le rôle important de l'inhibition récurrente dans la spécificité de la commande nerveuse lors de la contraction excentrique. Nous confirmons que le pilotage nerveux de la contraction excentrique peut être modulé par l'entraînement de force excentrique même si les modulations de l'excitabilité spinale semblent dépendre des caractéristiques de l'entraînement<br>The purpose of this PhD research is, on the one hand, to study the neural drive specificities during eccentric contractions by exploring the neural mechanisms involved at spinal level and, on the other hand, to examine the neural mechanisms responsible for the modulations of neuromuscular system following a strength submaximal eccentric training. Through this PhD research we highlight the contribution of recurrent inhibition by the Renshaw cell to the decrease of muscular activation typically observed during eccentric contraction. Furthermore, we show that recurrent inhibition is enhanced during submaximal contractions regardless of the contraction type. These results emphasize the important role of recurrent inhibition in the specificity of neural control during eccentric contractions. We confirm that the neural drive of the eccentric contraction may be modulated by eccentric strength training although modulations of spinal excitability seem to depend on the characteristics of training
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Blunt, Robert A. (Robert Andrew). "Influence of body weight support on soleus H-reflex modulation in normal and spinal cord injured human subjects during standing and walking." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59826.
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The soleus H-reflex modulation pattern was measured in 8 normal and 8 spastic paretic subjects during standing and walking, under the conditions of 0% and 40% body weight support (BWS). In standing, both the normal and patient groups showed no significant difference (p $<$ 0.01) in the H-reflex amplitude between 0% and 40% BWS. Normal subjects had a phase dependent modulation of the H-reflex during gait, there being no significant difference (p $<$ 0.001) in this modulation with 40% BWS. The patients had an abnormally elevated H-reflex throughout the step cycle, although five showed some modulation. In the patient group, 40% BWS produced a decrease of the H-reflex amplitude mainly in the push-off phase. BWS produced a decrease in electromyographic (EMG) mean burst amplitude of the lower limb muscles investigated, with more appropriate EMG activity timing. BWS improved knee and ankle angular displacements in patients, which were associated with an improved locomotor pattern. However, these improvements in locomotor pattern were not reflected clearly by changes in the H-reflex modulations. Thus the relationship between H-reflex amplitude, EMG activity, and ankle position under 0% and 40% BWS, needs to be further investigated.
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SALES, Rafael Moreira. "Efeito Agudo da Vibração de Corpo Inteiro no Nível de Excitabilidade Medular e Espaticidade dos Músculos Plantifexorores de individuos Espásticos Pós Acidente Vascular Encefálio: Um Ensaio Clínico Randomizado e Controlado." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/16553.
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Previous issue date: 2015-07-24<br>CNPQ<br>Introdução: A vibração de Corpo inteiro (VCI) tem sido sugerida como uma abordagem promissora na redução do nível de excitabilidade medular e no manejo da espasticidade. No entanto, ainda não é elucidado se o efeito existente de depressão do reflexo H após a vibração teria a persistência necessária para ter um potencial terapêutico e servir como preparação de indivíduos para a fisioterapia. Objetivo: Avaliar os efeitos agudos da VCI no nível de excitabilidade medular e na espasticidade dos músculos plantiflexores em indíviduos espásticos pós Acidente Vascular Encefálico (AVE) crônico. Métodos: Trata-se de um estudo piloto de um ensaio clínico contralado e randomizado, em que vinte e um homens com espasticidade plantiflexora foram distribuídos em dois grupos: vibração (GV, n=11) e controle (GC, n=10). O GV realizou três séries, uma de familiarização com duração de um minuto e depois duas de cinco minutos, de VCI com frequência de 35 Hz e amplitude de 2 mm, em posição ortostática com semiflexão do joelho a 40˚. O GC realizou o mesmo protocolo sem o estímulo vibratório. A espasticidade foi avaliada através da Escala Modificada de Ashworth (EMA) antes e 10 minutos após a intervenção. O nível de excitabilidade medular foi estimado pela razão Hmáx/Mmáx, e valor da razão H2/H1 e tempo para ocorrência do pico da primeira facilitação na curva de recuperação, antes e 10, 20 e 30 minutos após a intervenção. A percepção global de mudança do paciente também foi estimada após a intervenção. Resultados: Não foram encontradas diferenças significativas entre os grupos no nível de excitabilidade medular nos três momentos avaliados após a intervenção, bem como na espasticidade plantiflexora. Também não houve diferença na percepção global de mudança do paciente entre os grupos (RR: 1,21; IC95% 0,65 a 2,26). Conclusão: Os achados não mostram efeito da intervenção sobre o nível de excitabilidade medular e a espasticidade plantiflexora, nos tempos estudados. Portanto, a indicação da VCI como preparação para a fisioterapia nesta população não pôde ser suportada.<br>Background: Whole body vibration (WBV) has been suggested as a promising approach to reduce the level of spinal cord excitability and to treat spasticity. However, it is not clarified whether the existing depression effect of the H-reflex after the vibration have the persistence necessary to have a therapeutic potential and serve as subjects preparing for physiotherapy. Objective: To evaluate the acute effects of WBV on the level of spinal cord excitability and on plantarflexion spasticity in chronic post stroke individuals. Methods: It’s a pilot randomized controlled trial which twenty-one men with plantarflexion spasticity were allocated in two groups: vibration (VG, n = 11) and control (CG, n = 10). The VG held three series, one for familiarization lasting one minute and then two five minutes of WBV with frequency 35 Hz and amplitude of 2 mm, in the standing position with 40˚ of knee flexion. The CG went through the same protocol without vibration. The plantarflexion spasticity was evaluated by the Modified Ashworth Scale (MAS) before and 10 minutes after the intervention. The level of spinal cord excitability was estimated by the ratio Hmax/Mmax, the value of ratio H2/H1 and the time to occurrence of the first facilitation peak in the recovery curve before and 10, 20 and 30 minutes after the intervention. The patient global impression of change (PGIC) was also estimated after the intervention. Results: No significant differences were found between groups neither on the level of spinal cord excitability in the three moments evaluated after the intervention nor on plantarflexion spasticity. There was also no difference between groups in PGIC (RR: 1,21; CI95% 0,65 a 2,26). Conclusion: Our results show no effect of the intervention on the level of spinal cord excitability and on plantarflexion spasticity during the analyzed period. Therefore, the indication of the WBV in preparation for physiotherapy in this population could not be supported.
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Caron, Guillaume. "Etude de l'altération et de la récupération de la réponse des différents éléments de la boucle sensori-motrice." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4071/document.
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Le travail de cette thèse a permis de comparer les adaptations mises en place par le système nerveux après différentes méthodes d’altération et de récupération. Nos deux premières études portaient sur l’altérations de la réponse des afférences musculaires suite à une injection de toxine botulique. La troisième étude analysait la relation entre le phénotype musculaire et la réponse des afférences métabosensibles. Les deux dernières études analysaient si le vieillissement et l’activité physique altéraient la boucle sensori-motrice et la réponse des afférences métabosensibles. Les résultats de ce travail de thèse indiquent que la réponse des afférences mécano- et métabosensibles ont des profils de récupération qui diffèrent et que la réponse des afférences métabosensibles est dépendante en partie du phénotype musculaire. Enfin, le vieillissement induit une altération la boucle sensori-motrice, et l’entrainement permet de récupérer selon les muscles. L’activité des afférences métabosensibles est aussi altéré par les vieillissement mais l’entrainement ne permet pas de récupération<br>This thesis work compared nervous system adaptations after different methods of alteration and recovery. The two first studies were about muscle afferents response alterations following botulinum toxin injections. The third study analyzed the relation between muscle phenotype and metabosensitive response. The two last studies analyzed whether aging and physical activity could alter the metabosensitive response and the sensory-motor loop. Results indicate that mechano- and metabosensitive afferents response have different recovery pattern and that metabosensitive afferents response is in part dependent on the muscle phenotype. Aging results indicate an alteration of the sensory-motor loop and depending on the muscle, training allows a recovery. Metabosensitive afferents response is also altered but training does not induce a recovery
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McHenry, Colleen Louise. "Human limb vibration and neuromuscular control." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/1696.
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Mechanical loading can modulate tissue plasticity and has potential applications in rehabilitation science and regenerative medicine. To safely and effectively introduce mechanical loads to human cells, tissues, and the entire body, we need to understand the optimal loading environment to promote growth and health. The purpose of this research was 1) to validate a limb vibration and compression system; 2) to determine the effect of limb vibration on neural excitability measured by sub-threshold TMS-conditioned H-reflexes and supra-threshold TMS; 3) to determine changes in center of pressure, muscle activity, and kinematics during a postural task following limb vibration; 4) to determine the effect of vibration on accuracy and long latency responses during a weight bearing visuomotor task.
The major findings of this research are 1) the mechanical system presented in the manuscript can deliver limb vibration and compression reliably, accurate, and safely to human tissue; 2) sub-threshold cortical stimulation reduces the vibration-induced presynaptic inhibition of the H-reflex. This reduction cannot be attributed to an increase in cortical excitability during limb vibration because the MEP remains unchanged with limb vibration; 3) limb vibration altered the soleus and tibialis EMG activity during a postural control task. The vibration-induced increase in muscle activity was associated with unchanged center of pressure variability and reduced center of pressure complexity; 4) healthy individuals were able to accommodate extraneous afferent information due to the vibration interventions They maintained similar levels of accuracy of a visuomotor tracking task and unchanged long latency responses during an unexpected perturbation.
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Costa, Thaysi Cruz da. "?N?o h? revolu??o sem teoria?: express?es ideoculturais de g?nero e reflex?es acerca da p?s-modernidade e da cr?tica marxista." PROGRAMA DE P?S-GRADUA??O EM SERVI?O SOCIAL, 2016. https://repositorio.ufrn.br/jspui/handle/123456789/22102.
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Previous issue date: 2016-08-24<br>Esta disserta??o tem como objeto de pesquisa o embate te?rico-metodol?gico que gira em torno da discuss?o sobre g?nero, especificamente, no que tange as perspectivas de an?lise marxista e p?s-moderna. Considerando-se que essas perspectivas apresentam categorias te?ricas divergentes e que v?o de encontro na forma de analisar a realidade social e as rela??es nela presentes, apontando, assim, diferentes proposi??es e direcionamentos. Nesse sentido, este trabalho tem como objetivo geral: analisar o debate de g?nero no campo do marxismo e da p?s-modernidade; e como objetivos espec?ficos: apreender as principais categorias de an?lise do marxismo e da p?s-modernidade; realizar um levantamento das produ??es dos anais do evento Fazendo G?nero; identificar as principais tend?ncias e perspectivas te?ricas que vem se destacando nesse evento. Diante dessa configura??o, buscamos, por meio desta pesquisa, problematizar essas quest?es com base nas publica??es de comunica??o oral realizadas no Semin?rio Internacional Fazendo G?nero. A partir de uma abordagem qualitativa, buscamos construir este trabalho realizando a coleta de dados e a pesquisa bibliogr?fica acerca do tema. Nesse processo, optamos por fazer um recorte para chegar a amostra final da nossa pesquisa, levando em considera??o a amplitude do evento e a grande quantidade de artigos nele publicados, desse modo, foram coletados os dados dos Anais do Semin?rio Internacional Fazendo G?nero 7 ao 10, pois estes eram os que se encontravam dispon?veis no site do evento. Para elabora??o da an?lise foram escolhidos 80 artigos, dos quais tentamos explorar as reflex?es propostas pelos autores, bem como as principais categorias de an?lise, m?todo utilizado, ?rea tem?tica, referencial bibliogr?fico e de que forma as quest?es de g?nero s?o abordadas diante desses elementos. Podemos observar, nesse curto espa?o de an?lise, que h? uma tend?ncia crescente na produ??o sobre g?nero no campo da perspectiva p?s-moderna, sua predomin?ncia n?o se explica apenas por fatores hist?ricos, uma vez que, o g?nero nasceu dessa fonte, como tamb?m em virtude das diferentes formas com que esta categoria ? apreendida. Isso porque, no marxismo o g?nero ? visto enquanto fen?meno que faz parte das express?es da quest?o social e que, dessa forma, dialoga com a totalidade da vida social; enquanto na p?s-modernidade ? visto como um elemento da subjetividade, e por isso, suas an?lises se d?o predominantemente no campo do imagin?rio, do simb?lico e do cultural. Percebemos, tamb?m, que h? muito pontos que necessitam ser problematizados nas abordagens sobre g?nero, visto que, grande parte dos artigos, apresentaram uma an?lise superficial da conjuntura em que est?o inseridas as rela??es sociais, principalmente no que diz respeito ao posicionamento pol?tico-ideol?gico na constru??o e transforma??o social, como tamb?m na cr?tica ? ordem vigente. A aus?ncia desses elementos configura um cen?rio de imediatismo e de volatilidade no trato de quest?es que merecem uma reflex?o mais consistente, tendo em vista a conjuntura s?cio-pol?tica que vivenciamos hoje.<br>This dissertation has as object of research the theoretical-methodological clash that revolves around the discussion about gender, specifically, regarding the perspectives of Marxist and postmodern analysis. Considering that these perspectives present divergent theoretical categories and that they encounter in the form of analyzing the social reality and the relations in them present, pointing, therefore, different propositions and directions. In this sense, this work has as general objective: to analyze the gender debate in the field of Marxism and postmodernity; And as specific objectives: to apprehend the main categories of analysis of Marxism and postmodernity; Perform a survey of the annals of the Making of Gender event; Identify the main trends and theoretical perspectives that have been highlighted in this event. Given this configuration, we seek, through this research, to problematize these issues based on the oral communication publications held at the International Seminar on Gender Making. From a qualitative approach, we seek to build this work by performing data collection and bibliographic research on the subject. In this process, we chose to make a cut to arrive at the final sample of our research, taking into account the amplitude of the event and the large number of articles published in it, thus, data were collected from the Annals of the International Seminar Making Gender 7 to 10, since these were the ones that were available in the site of the event. For the elaboration of the analysis, we selected 80 articles, from which we tried to explore the reflections proposed by the authors, as well as the main categories of analysis, method used, thematic area, bibliographic reference and how gender issues are approached before these elements. We can observe, in this short space of analysis, that there is an increasing tendency in production on gender in the field of the postmodern perspective, its predominance is not only explained by historical factors, since the genre was born from this source, but also by virtue Of the different ways in which this category is seized. This is because, in Marxism, gender is seen as a phenomenon that forms part of the expressions of the social question and, in this way, dialogues with the totality of social life; While in postmodernity it is seen as an element of subjectivity, and therefore, its analyzes take place predominantly in the field of imaginary, symbolic and cultural. We also noticed that there are many points that need to be problematized in the approaches on gender, since a large part of the articles presented a superficial analysis of the conjuncture in which social relations are inserted, mainly with regard to the political-ideological position in the Construction and social transformation, as well as in the critique of the current order. The absence of these elements constitutes a scenario of immediacy and volatility in dealing with issues that deserve a more consistent reflection, given the socio-political context we are experiencing today.
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Colard, Julian. "Caractérisation des réponses neurophysiologiques aiguës et chroniques à l’exercice excentrique : influence de la longueur musculaire." Electronic Thesis or Diss., Nantes Université, 2024. http://www.theses.fr/2024NANU1027.
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Les contractions excentriques engendrent un contrôle nerveux distinct par rapport aux contractions isométriques et concentriques. Bien que certains mécanismes postsynaptiques, tels que l'inhibition récurrente, aient été identifiés comme jouant un rôle dans cette commande spécifique, l'implication des mécanismes présynaptiques reste à démontrer. Comme les contraintes mécaniques augmentent particulièrement en phase finale des contractions excentriques, les variations de longueur musculaire peuvent entraîner des retours afférents (Ia et II) différents vers la moelle épinière, affectant alors l’activité du motoneurone. L’objectif de cette thèse était d’explorer (i) les caractéristiques du système nerveux pendant les contractions excentriques, (ii) d’évaluer l’influence de la longueur musculaire sur le contrôle nerveux lors d’allongements musculaires passifs et actifs (contractions excentriques), et (iii) de déterminer si la longueur musculaire peut moduler les réponses adaptatives à long terme observées après un entraînement excentrique. Quatre études ont contribué à ce travail de thèse. Ces études ont mesuré des paramètres mécaniques, tels que le moment de force et la longueur des faisceaux musculaires, ainsi que des paramètres nerveux, incluant l’excitabilité corticospinale, l’efficacité de la transmission de l’influx nerveux entre les fibres afférentes Ia et les motoneurones α, le gain réflexe, les mécanismes régulateurs sous-jacents et l'activité électromyographique des muscles. Les résultats montrent que les mécanismes présynaptiques constituent un facteur déterminant dans le contrôle nerveux des contractions excentriques. Les variations de longueur musculaire, notamment lors des phases à grande longueur, influencent distinctement l’activité des mécanismes inhibiteurs spinaux durant les allongements passifs et actifs. Enfin, la longueur musculaire pourrait favoriser la plasticité neurale à long terme, en optimisant plus efficacement les mécanismes sous-jacents pour des contractions sous-maximales. Cependant, pour des contractions maximales, le système nerveux semble limiter les adaptations, reflétant peut-être un mécanisme protecteur<br>Eccentric contractions induce distinct neural control compared to isometric and concentric contractions. Although some postsynaptic mechanisms, such as recurrent inhibition, have been identified as playing a role in this specific control, the involvement of presynaptic mechanisms remains to be demonstrated. As mechanical constraints increase particularly in the final phase of eccentric contractions, variations in muscle length may lead to different afferent feedback (Ia and II) to the spinal cord, thereby affecting motoneuron activity. The aim of this thesis was to explore (i) the characteristics of the nervous system during eccentric contractions, (ii) to assess the influence of muscle length on neural control during passive and active (eccentric contractions) muscle elongations, and (iii) to determine whether muscle length can modulate the long-term adaptive responses observed following eccentric training. Four studies contributed to this thesis. These studies measured mechanical parameters, such as torque and muscle fascicle length, as well as neural parameters, including corticospinal excitability, the efficiency of synaptic transmission between Ia afferent fibres and α- motoneurons, reflex gain, underlying regulatory mechanisms, and electromyographic activity of the muscles. The results indicate that presynaptic mechanisms play a crucial role in the neural control of eccentric contractions. Variations in muscle length, particularly during phases at long length, distinctly influence the activity of spinal inhibitory mechanisms during both passive and active elongations. Finally, muscle length may promote long-term neural plasticity by more effectively optimising the underlying mechanisms for submaximal contractions. However, for maximal contractions, the nervous system appears to limit adaptations, potentially reflecting a protective mechanism
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Vila-Chã, Carolina. "Electrophysiological assessment of neuromuscular adaptations to training." Doctoral thesis, Universidade do Porto, Faculdade de Engenharia, 2011. http://hdl.handle.net/10198/6908.
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Over the last decades, it has been shown that the human neuromuscular system is highly adaptive and can be modified in response to different motor training programs. Depending on the demands of the motor training, the adaptations seem to involve distinct structural and functional changes across the motor cortex, spinal cord and skeletal muscle. The technological development observed in the last years, increased the use of electrophysiological techniques to assess the neuromuscular adaptations to motor training. Nonetheless, the current evidences on the neuromuscular adaptations to different motor training are inconsistent and incomplete, in particular regarding endurance and strength training. This is mainly due to lack of studies based on a rigorous consideration of the limitations of the available techniques. Therefore, the main goal of this dissertation is to give new insights on the adaptations of the neuromuscular system by systematically investigating the changes in its central and peripheral properties in response to endurance and strength training. For this purpose, recent developed techniques for recording and processing electromiographycal (EMG) signals were applied. The first study (STUDY I) investigated if 6 weeks of either endurance or strength training alters the motor unit behavior and if such changes were accompanied by alterations in muscle fiber properties. Intramuscular and multichannel surface EMG recordings were used to investigate the motor unit discharge rates and motor unit conduction velocity (MUCV) of the vastus medialis obliquus and vastus lateralis during submaximal isometric contractions. The results demonstrated that endurance training increased endurance capacity and was accompanied by a decrease of the motor unit discharge rates. In contrast, strength training enhanced maximum force output and was accompanied by an increase of the motor unit discharge rates. By the end of 6 weeks of training, both training programs elicited increases in the motor unit conduction velocity, revealing electrophysiological adaptations of the muscle fiber membrane properties in similar directions. However, in the first 3 weeks of training, when changes in motor unit discharge rates were most marked, changes in MUCV were not observed. These findings reveal different time courses of some of the neural and peripheral adaptations in response to different motor training programs. The observed changes may contribute for distinct neuromuscular fatigue profiles among endurance and strength-trained athletes. Therefore, the aim of the second study (STUDY II) was to investigate the effects of 6 weeks of endurance and a strength training program on acute responses of the muscle fiber membrane properties and discharges rates of low threshold motor units of the vastus medialis obliquus and vastus lateralis muscles during prolonged submaximal isometric contractions. The conduction velocity of the individual motor units was estimated from the averaged multichannel EMG surface potentials by a spike triggered average technique. It was shown that motor unit discharge rate declines over the duration of the sustained contraction and their trend was not significantly affected by training. Conversely, the rate of decline of motor unit conduction velocity during sustained contractions was reduced following six weeks of both endurance and strength training, however a greater reduction is observed following endurance training. These alterations likely contribute to longer times to task failure following endurance training. The third study (STUDY III) intended to clarify the mechanisms involved in the opposite adjustments of the motor unit discharge rate observed in the study I. The results revealed that following 3 weeks of endurance training the excitability in the H-reflex pathway increased but the V-wave amplitude remained unchanged. In contrast, following strength training the V-wave amplitude increased whereas subtle changes were observed in the H-reflex pathway. These results suggest that the elements of the H-reflex pathway are strongly involved in chronic adjustments in response to endurance training, contributing to enhance resistance to fatigue. Conversely, following strength training, it is more likely that increased descending neural drive during MVC and/or modulation in afferents other than Ia afferents contributed to increased motoneuron excitability and maximal voluntary contraction.
The present work revealed for the first time that endurance and strength training induces opposite adjustments in the motor unit behavior. Moreover, the distinct adjustments in the spinal cord output, seems to result from changes in different neural mechanisms located at supraspinal and/or spinal level. The neural adjustments following endurance training seems to result from changes at spinal level whereas the adjustments following strength training are likely due to changes at supraspinal level. These adaptations occurred following a short period of training, while no changes in the contractile and electrophysiological properties of the muscle fibers were detectable. Changes at peripheral level occurred only following a longer period of training.
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Traverse, Elodie. "Mécanismes neurophysiologiques de l'imagerie motrice : effet d'une stimulation somatosensorielle associée." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCK065/document.
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L’entrainement mental (EM) par imagerie motrice (IM), qui consiste à simuler mentalement une action sans production motrice, constitue un stimulus efficace pour l’amélioration de la force maximale volontaire. Si aucun retour afférent sensitif n’est présent au cours d’une tâche d’IM, il n’en reste pas moins qu’une activation du cortex somatosensoriel est reportée. En effet, l’efficacité de l’IM repose en partie sur une interaction entre les voies motrices et les voies sensitives. Ainsi, il apparait raisonnable de penser que l’ajout de retours afférents sensitifs pendant l’IM pourrait potentialiser les effets de cette dernière et donc améliorer la performance motrice. L’objectif de cette thèse était d’analyser les mécanismes nerveux impliqués dans l’imagerie motrice combinée à la stimulation somatosensorielle. Dans notre première étude, nous avons montré que l’ajout d’une stimulation somatosensorielle des afférences Ia pendant une tâche d’imagerie pouvait potentialiser l’excitabilité corticospinale. Notre deuxième étude n’a cependant pas permis de mettre en évidence une meilleure efficacité d’un entrainement en imagerie motrice combinée à la stimulation somatosensorielle comparativement à un entrainement par imagerie motrice ou par stimulation somatosensorielle seules sur la force maximale volontaire. Enfin, notre troisième étude suggère que cette apparente inefficacité de la stimulation somatosensorielle à potentialiser les effets de l’imagerie, pourrait être en partie liée à un conflit entre l’activation du réseau neuronal en imagerie et l’activation de mécanismes corticaux suite aux retours afférents induits par la SS<br>Mental training, which involves mentally simulating an action without motor output, is an effective stimulus to improve the maximal voluntary contraction. If only the motor pathway is activated, an activation of the somatosensory cortex is observed despite the lack of afferent feedback. Indeed, the motor imagery task efficiency is based in part on an interaction between motor and sensory pathway. Thus, it’s seems reasonable to think that the addition of sensory afferent feedback during motor imagery could potentiate the motor imagery effects and thus improve motor performance. In our first study, we showed that the addition of somatosensory stimulation of Ia-afferents during a motor imagery task could potentiate corticospinal excitability. Our second study, however, did not show a better efficacy of a mental training combined with somatosensory stimulation compared to a mental training or a somatosensory stimulation training alone on the maximal voluntary contraction. Finally, our third study suggests that this apparent inefficiency of somatosensory stimulation to potentiate the effects of motor imagery may be partly related to a conflict between the activation of the neuronal network in imaging and the activation of cortical mechanisms following the afferents feedbacks induced by the somatosensory stimulation
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Pineau, Antoine. "Stimulation électrique et étirement musculaire : Effets sur le système neuromusculaire." Electronic Thesis or Diss., Bourgogne Franche-Comté, 2024. http://www.theses.fr/2024UBFCK059.
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L'objectif de cette thèse était d'évaluer les effets de la combinaison de la stimulation électrique neuromusculaire (NMES) de type wide-pulse (WP) et de l'étirement musculaire sur la production de force et le système neuromusculaire. Ce travail s'appuie sur l’hypothèse que l’activation préférentielle des voies afférentes induite par la NMES WP serait maximisée par l’ajout de l’étirement musculaire et aurait un impact sur la production de force. Les trois premières études de cette thèse ont cherché à identifier les conditions optimales de cette combinaison, en modulant la vitesse et l’amplitude de l’étirement ainsi que les paramètres de stimulation. Les résultats de ces travaux ont montré que : i) lorsque les hautes fréquences de stimulation sont utilisées (100 Hz), un étirement d’une amplitude de 10° est suffisant pour augmenter la force évoquée, indépendamment de la vitesse d’étirement. Pour obtenir le même effet lorsque les basses fréquences de stimulation sont utilisées (20 Hz), la position de la cheville doit être maintenue étirée. ii) Pour bénéficier de l’effet de l’étirement sur la production de force, l’activation des voies afférentes doit être préalablement importante et iii) l’ajout de l’étirement lors de trains de stimulation répétés permet le maintien de la force évoquée au cours des trains de stimulation. L’effet de l’application combinée de la NMES WP et de l’étirement musculaire semble être attribuable à une sollicitation plus importante des voies afférentes<br>The aim of this thesis was to evaluate the effects of combining wide-pulse neuromuscular electrical stimulation (NMES WP) with muscle lengthening on force production and the neuromuscular system. This work is based on the hypothesis that the preferential activation of afferent pathways induced by NMES WP would be maximized by the superimposed muscle lengthening and would impact force production. The first three studies of this thesis aimed to identify the optimal conditions for this combination by modulating the speed and amplitude of the stretch, as well as the stimulation parameters. Results of these studies showed that: i) when high stimulation frequencies are used (100 Hz), a lengthening on a 10°-amplitude is sufficient to increase the evoked force regardless of lengthening speed. To obtain the same effect when low stimulation frequencies are used (20 Hz), the ankle position must be held in the stretched position. ii) To benefit from the effect of lengthening on force production, activation of afferent pathways must be significant beforehand, and iii) the addition of lengthening during repeated stimulation trains allows a preserved evoked force throughout the stimulation trains. The effect of combining NMES WP with muscle lengthening seems to be attributable to increased afferent pathway activation
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Almeida, Silveira Maria Izabel. "Approche neurophysiologique et biomécanique de l'adaptation du muscle de rat à l'hyperactivité." Compiègne, 1993. http://www.theses.fr/1993COMP638S.
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Quel que soit le critère analysé (mécanique, neurophysiologique, métabolique ou histochimique), il apparaît que les muscles striés squelettiques sont hétérogènes et que leur myotypologie dépend de leurs caractéristiques fonctionnelles. Les études dans ce domaine ont conduit à s'interroger sur les parts respectives jouées par la détermination génétique et par la capacité d'interconversion des différents types de fibres (plasticité musculaire) du muscle soumis à modifications de demande fonctionnelle. Ce travail concerne une étude multidisciplinaire de l'adaptation du muscle de rat soumis à l'hyperactivité. Deux modèles de surcharge sont appliqués sur le groupe musculaire extenseur de la cheville : le premier modèle correspond à un entraînement en endurance, le second modèle consiste en une répétition de cycle étirement-détente (entraînement pliométrique). Le premier chapitre de cette thèse est consacré à une analyse bibliographique concernant la plasticité du muscle strié squelettique et les modèles expérimentaux utilisés pour attester des principales modifications neuro-musculaires. Dans la seconde partie une description détaillée des méthodes utilisées dans l'approche multidisciplinaire (mécanique, réflexologique et histochimique) est présentée. Les paramètres mécaniques mesurés pour caractériser les propriétés contractiles montrent qu'un changement de la cinétique de contraction du muscle soleus peut avoir lieu, soit dans le sens d’une diminution de la célérité du muscle lors de l'entraînement en endurance, soit dans le sens d'une augmentation de la célérité lors de l'entraînement pliométrique. Les caractéristiques de la Composante Elastique Série du muscle soleus peuvent aussi évoluer selon le type de demande fonctionnelle : une augmentation de raideur est observée après l'application de l'entraînement en endurance et une augmentation de compliance après l'entraînement pliométrique. La transposition au rat des techniques réflexologiques humaines (recherche de la réponse de Hoffmann et de la réponse tendineuse) a été réalisée de façon tout à fait originale dans le cadre de ce travail. Cela a permis de proposer un phénomène de latéralisation du réflexe de Hoffmann. D’autre part, cette étude montre que chez l'animal comme chez l'homme l'analyse réflexologique peut fournir un indice de la plasticité musculaire. Ainsi, une augmentation de l'excitabilité réflexe est constatée sur le groupe musculaire hyperactivé par un entraînement en endurance et l'effet inverse est observé par l'application de l'entraînement pliométrique. Cet ensemble de résultats sont confortés par l'étude histochimique qui montre la possibilité de conversion de fibres aussi bien dans la direction rapide vers lent lors de l'entraînement en endurance, et dans le sens lent vers rapide lors de l'entraînement pliométrique.
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Gao, Ying. "A Digital Signal Processing Approach for Affective Sensing of a Computer User through Pupil Diameter Monitoring." FIU Digital Commons, 2009. http://digitalcommons.fiu.edu/etd/132.
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Recent research has indicated that the pupil diameter (PD) in humans varies with their affective states. However, this signal has not been fully investigated for affective sensing purposes in human-computer interaction systems. This may be due to the dominant separate effect of the pupillary light reflex (PLR), which shrinks the pupil when light intensity increases. In this dissertation, an adaptive interference canceller (AIC) system using the H∞ time-varying (HITV) adaptive algorithm was developed to minimize the impact of the PLR on the measured pupil diameter signal. The modified pupil diameter (MPD) signal, obtained from the AIC was expected to reflect primarily the pupillary affective responses (PAR) of the subject. Additional manipulations of the AIC output resulted in a processed MPD (PMPD) signal, from which a classification feature, PMPDmean, was extracted. This feature was used to train and test a support vector machine (SVM), for the identification of stress states in the subject from whom the pupil diameter signal was recorded, achieving an accuracy rate of 77.78%. The advantages of affective recognition through the PD signal were verified by comparatively investigating the classification of stress and relaxation states through features derived from the simultaneously recorded galvanic skin response (GSR) and blood volume pulse (BVP) signals, with and without the PD feature. The discriminating potential of each individual feature extracted from GSR, BVP and PD was studied by analysis of its receiver operating characteristic (ROC) curve. The ROC curve found for the PMPDmean feature encompassed the largest area (0.8546) of all the single-feature ROCs investigated. The encouraging results seen in affective sensing based on pupil diameter monitoring were obtained in spite of intermittent illumination increases purposely introduced during the experiments. Therefore, these results confirmed the benefits of using the AIC implementation with the HITV adaptive algorithm to isolate the PAR and the potential of using PD monitoring to sense the evolving affective states of a computer user.
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Sanders, Grant D. "THE EFFECTS OF SPINAL MANIPULATIVE THERAPY ON ISOKINETIC STRENGTH AND POSTACTIVATION POTENTIATION." UKnowledge, 2015. http://uknowledge.uky.edu/khp_etds/27.
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Spinal manipulative therapy (SMT) is a therapeutic procedure employed by various healthcare practitioners for alleviating acute and chronic musculoskeletal complaints. This form of treatment is also delivered to enhance the performance and augment the rehabilitation of athletes. However, despite research findings alleging the strength-modulating effects of SMT alongside numerous professional athletes’ positive anecdotal claims concerning its results, the physiological processes to explain its effects remain largely unexplained. Therefore, the purpose of this work was to investigate the effects of SMT in a college-aged sample population with two experiments.
The first study examined the effect of SMT targeting the lumbosacral region on concentric force production of the knee extensors and flexors. A randomized, controlled, single-blind crossover design was utilized with 21 subjects. Isometric and isokinetic peak torques (Nm) were recorded during maximal voluntary isometric contractions (MVIC) or maximal voluntary contractions (MVC) post-treatment of either SMT or a sham manipulation. The second study incorporated the same experimental design with 20 subjects to examine the effects of SMT on central nervous system (CNS) excitability. This was accomplished by assessing postactivation potentiation (PAP), measured with the Hoffmann Reflex (H-reflex). PAP is an enhanced neuromuscular response to prior contractile activity, and the H-reflex is the electromyographic (EMG) recording of submaximal electrical stimulation of the Ia monosynaptic reflex pathway. Subsequent to SMT and/or a plantar flexion MVIC, EMG amplitudes and isometric twitch torque generation of the gastrocnemius and soleus muscles were recorded during tibial nerve stimulations.
The results of the first study indicate that SMT did not produce a significant strength-modulating effect during isometric and isokinetic contractions of neither knee extension nor flexion. Similarly, the second study revealed that SMT immediately preceding the MVIC to induce PAP did not significantly increase H-reflex EMG amplitudes of either muscle or the simultaneous isometric twitch torque generation compared to the MVIC only. These data from both investigations suggest that SMT does not enhance strength or PAP. The positive anecdotal claims of athletes who utilize SMT may be due to other factors, such as the clinical efficacy of the treatment in addressing musculoskeletal injuries or a placebo effect.
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Vuk, Stevanović. "Акутни ефекти различитих садржаја уводно-припремног дела тренинга на моторичке способности и неуромишићну адаптацију кошаркаша". Phd thesis, Univerzitet u Novom Sadu, Fakultet sporta i fizičkog vaspitanja u Novom Sadu, 2016. https://www.cris.uns.ac.rs/record.jsf?recordId=101038&source=NDLTD&language=en.
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Циљ рада: Циљ истраживања је да се утврди разлика у акутним ефектима статичког (СИ) и динамичког истезања (ДИ), у комбинацији са специфичним кошаркашким загревањем (СКЗ), на флексибилност, експлозивну снагу ногу, брзину, агилност и неуромишићну адаптацију кошаркаша јуниорског узраста.Методе: Истраживање у оквиру ове докторске тезе су чинила два одвојена експеримента, један спроведен у теренским условима, и други спроведен у лабораторијским. Оба су била „cross-over“ дизајна. У теренском експерименту је учествовало 46 кошаркаша (узраста 17±0,83 година), док је у лабораторијском учествовало 12 (узраста 17,7±0,49 година). У теренском експерименту су тестиране четири моторичке способности. За процену флексибилности коришћен је тест досезања у седећем претклону, експлозивна снага ногу је процењивана уз помоћ вертикалног скока са контактне плоче, брзина трчањем на 20 метара, док је Т тест коришћен за процену агилности. У лабораторијском експерименту је као мера неурофизиолошке адаптације коришћена промена ексцитабилности α-мотонеурона, која је представљена као однос Хофмановог (Х) рефлекса и М таласа (Х/М). За њихово одређивање се користио Medelec ST-10 стимулатор (Medelec, Old Woking, UK). Површинске електромиографске електроде су биле постављене на унутрашњој глави m.gastrocnemius-a одскочне ноге, применом тзв. „belly-tendon“ монтаже. Као третмани, у оба експеримента су коришћени протокол статичког и протокол динамичког истезања, уз комбинацију са специфичним кошаркашким загревањем. Мерења су се у оба експеримента изводила у 3 временске тачке и то пре протокола истезања, одмах након протокола истезања (а пре специфичног кошаркашког загревања) и одмах након специфичног кошаркашког загревања.Резултати: Резултати истраживања показују да постоје одређене разлике акутних ефеката комбинација протокола СИ+СКЗ и ДИ+СКЗ. Комбинација протокола СИ+СКЗ је повољније утицала на експлозивну снагу ногу и на агилност кошаркаша јуниорског узраста. Ефекти обе комбинације протокола су били готово идентични на флексибилност, а разлика је изостала и у ефектима на брзину, иако је пре СКЗ био уочљив негативан ефекат СИ. Однос Х/М се значајно разликовао одмах након истезања, када је СИ значајно оборило однос, али су се те разлике изгубиле након примене СКЗ.Закључак: Посматрајући ефекте комбинације протокола СИ+СКЗ и ДИ+СКЗ на моторичке способности и неуромишићну адаптацију кошаркаша јуниорског узраста, може се закључити да је примена СИ+СКЗ препоручљивија у свакодневном тренингу и такмичењу.<br>Cilj rada: Cilj istraživanja je da se utvrdi razlika u akutnim efektima statičkog (SI) i dinamičkog istezanja (DI), u kombinaciji sa specifičnim košarkaškim zagrevanjem (SKZ), na fleksibilnost, eksplozivnu snagu nogu, brzinu, agilnost i neuromišićnu adaptaciju košarkaša juniorskog uzrasta.Metode: Istraživanje u okviru ove doktorske teze su činila dva odvojena eksperimenta, jedan sproveden u terenskim uslovima, i drugi sproveden u laboratorijskim. Oba su bila „cross-over“ dizajna. U terenskom eksperimentu je učestvovalo 46 košarkaša (uzrasta 17±0,83 godina), dok je u laboratorijskom učestvovalo 12 (uzrasta 17,7±0,49 godina). U terenskom eksperimentu su testirane četiri motoričke sposobnosti. Za procenu fleksibilnosti korišćen je test dosezanja u sedećem pretklonu, eksplozivna snaga nogu je procenjivana uz pomoć vertikalnog skoka sa kontaktne ploče, brzina trčanjem na 20 metara, dok je T test korišćen za procenu agilnosti. U laboratorijskom eksperimentu je kao mera neurofiziološke adaptacije korišćena promena ekscitabilnosti α-motoneurona, koja je predstavljena kao odnos Hofmanovog (H) refleksa i M talasa (H/M). Za njihovo određivanje se koristio Medelec ST-10 stimulator (Medelec, Old Woking, UK). Površinske elektromiografske elektrode su bile postavljene na unutrašnjoj glavi m.gastrocnemius-a odskočne noge, primenom tzv. „belly-tendon“ montaže. Kao tretmani, u oba eksperimenta su korišćeni protokol statičkog i protokol dinamičkog istezanja, uz kombinaciju sa specifičnim košarkaškim zagrevanjem. Merenja su se u oba eksperimenta izvodila u 3 vremenske tačke i to pre protokola istezanja, odmah nakon protokola istezanja (a pre specifičnog košarkaškog zagrevanja) i odmah nakon specifičnog košarkaškog zagrevanja.Rezultati: Rezultati istraživanja pokazuju da postoje određene razlike akutnih efekata kombinacija protokola SI+SKZ i DI+SKZ. Kombinacija protokola SI+SKZ je povoljnije uticala na eksplozivnu snagu nogu i na agilnost košarkaša juniorskog uzrasta. Efekti obe kombinacije protokola su bili gotovo identični na fleksibilnost, a razlika je izostala i u efektima na brzinu, iako je pre SKZ bio uočljiv negativan efekat SI. Odnos H/M se značajno razlikovao odmah nakon istezanja, kada je SI značajno oborilo odnos, ali su se te razlike izgubile nakon primene SKZ.Zaključak: Posmatrajući efekte kombinacije protokola SI+SKZ i DI+SKZ na motoričke sposobnosti i neuromišićnu adaptaciju košarkaša juniorskog uzrasta, može se zaključiti da je primena SI+SKZ preporučljivija u svakodnevnom treningu i takmičenju.<br>Objective: The aim of this study was to determine the difference of acute effects of static stretching (SS) and dynamic stretching (DS), in combination with specific basketball warm-up (SBWU), on flexibility, explosive leg strength, speed, agility and neuromuscular adaptation of basketball players U18.Methods: This study consisted of two separated experiments, first in field conditions, and second conducted in laboratory. Both had „cross-over“ design. Forty-six basketball players (age: 17±0,83 years) participated in field experiment, while twelve participated in laboratory experiment (age 17,7±0,49 years). In field experiment, four motor abilities were tested. Seat and rech test was used for the evaluation of flexibility, explosive leg strength was evaluated by vertical jump from contact plate, speed by 20m run, and T test was used for agility testing. In laboratory experiment, the excitability of α-motoneuron was taken for the evaluation of neuromuscular adaptation. It is presented as a ratio of the maximal amplitudes of Hoffman (H) reflex and M wave (H/M). For their determining we used Medelec ST-10 stimulator (Medelec, Old Woking, UK). Surface electromyographic (EMG) electrodes were placed over the m.gastrocnemius medialis, and Achilles tendon, in a „belly-tendon“ montage. In both experiments, SS protocol and DS protocol, in the combination with SBWU, were used as a treatment. Measures were taken in 3 time points: before the stretching, immediately after stretching (and before SBWU) and immediately after the SBWU.Results: Results of this study showed that there are certain differences in acute effects of combination of protocols SS+SBWU and DS+SBWU. Combination of protocols SS+SBWU had more positive influence on explosive leg strength and agility of U18 basketball players. The effects of both protocols were almost the same on flexibility, and there was no noticeable difference in effects on speed, although before SBWU there was significant negative of SS. Immediately after the stretching there was significant difference in H/M ratio, it was significantly lower after the SS, but after the application of SBWU, differences disappeared. Conlcusion: Regarding the effects of SS+SBWU and DS+SBWU protocols on motor abilities and neuromuscular adaptation of U18 basketball players, it could be concluded that the use of SS+SBWU is more preferrable in everyday practice and competition.
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Souza, Alysson Amancio de. "E...5,6,7,8: reflex?es sobre processos formativos em dan?a na contemporaneidade." PROGRAMA DE P?S-GRADUA??O EM ARTES C?NICAS, 2015. https://repositorio.ufrn.br/jspui/handle/123456789/21595.
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Previous issue date: 2015-09-24<br>A presente pesquisa tem como objetivo principal refletir sobre os processos n?o formais desenvolvidos em dan?a na contemporaneidade. Os cursos livres, escolas, academias, ONGs e associa??es ainda s?o as institui??es que mais formam bailarinos no Brasil (STRAZZACAPPA, 2012), nesse sentido julgamos necess?rio cont?nuas pesquisas que possam discutir e contribuir para a potencializa??o destes espa?os. Por conseguinte, este trabalho ? fundamentado metodologicamente na abordagem fenomenol?gica e mais especificamente na an?lise do fen?meno situado, tendo como campo constitutivo de estudo uma institui??o de ensino n?o formal do interior do Cear?, a Associa??o Dan?a Cariri (ADC), existente desde 2007, a qual vem fomentando diversas atividades culturais na regi?o do Cariri, sul deste estado. A partir desse contexto, a presente pesquisa aborda uma reflex?o sobre como a forma??o de ensino h?brida, proposta pela ADC, vem influenciando os artistas locais e modificando os corpos sujeitos e o ambiente da dan?a do Cariri, atrav?s de composi??es coreogr?ficas, aumento de eventos de dan?a, implementa??o de novos espa?os e pesquisas em dan?a, traduzindo-se, portanto, em um campo constitutivo voltado ? forma??o, a difus?o e ao desenvolvimento da dan?a na contemporaneidade.<br>This research aims to contribute to a reflection on the non-formal processes developed in dance nowadays. Free courses, schools, academies, ONGs and associations are still the institutions that make up more dancers in Brazil (STRAZZACAPPA, 2012), in this sense we consider necessary ongoing research that can discuss and contribute to the enhancement of these spaces. Therefore, this work is based methodologically on the phenomenological approach and more specifically in the analysis of situated phenomenon, with the constitutive field study a non-formal educational institution in the interior of Cear?, the Association Dance Cariri (ADC), existing since 2007, which has fueled various cultural activities in Cariri, south of this state. From this context, this research addresses a reflection on how the formation of hybrid teaching, proposed by the ADC, is contaminating local artists and modifying the subjects bodies and the Cariri dance environment through choreographic compositions, event increased dance, implementation of new spaces and research in dance, resulting therefore in a constitutive field relates to education, dissemination and development of dance in contemporary times.
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Pazzinatto, Marcella Ferraz. "A alteração na modulação do reflexo-H é um fator de risco para dor femoropatelar? /." Presidente Prudente, 2019. http://hdl.handle.net/11449/190989.
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Orientador: Fábio Mícolis de Azevedo<br>Resumo: A dor femoropatelar (DFP) é uma das condições mais comuns na prática ortopédica, e evidências recentes sugerem que pode ser um fator predisponente à osteoartrite femoropatelar. Além das alterações biomecânicas associadas ao patomecanismo subjacente à DFP, a investigação de alterações neurofisiológicas pode fornecer novas informações no entendimento da fisiopatologia da DFP. Nesse sentido, o reflexo de Hoffmann (reflexo-H), o homólogo elétrico do reflexo de estiramento, tem sido utilizado na tentativa de entender melhor como o sistema nervoso central integra os sinais descendentes com os aferentes periféricos, como uma medida indireta da excitabilidade espinal. Esta tese teve como objetivo investigar de forma abrangente o papel do reflexo H em mulheres com DFP. Primeiramente, um estudo transversal foi proposto com o objetivo de facilitar a implementação de medidas neurofisiológicas no ambiente clínico, através da avaliação do reflexo tendíneo (reflexo-T), utilizando um martelo clínico simples. Os resultados deste e de outros estudos previamente publicados pelo nosso grupo de pesquisa instigaram os autores a levantar a hipótese de que a menor amplitude do reflexo-H seja um fator de risco ou uma consequência da DFP. Para responder a essa pergunta, os autores propuseram um estudo prospectivo de coorte observacional de 1 ano. Diante dos resultados apresentados nesta tese, entende-se a contribuição dos aspectos neurofisiológicos na DFP.<br>Abstract: Patellofemoral pain (PFP) is one of the most common conditions in orthopedic practice while recent evidence has suggested that it may be a predisposing factor to patellofemoral osteoarthritis. In addition to biomechanical alterations associated with the pathomechanisms underlying PFP, the investigation of neurophysiological alterations might provide novel information in the understanding of the pathophysiology of PFP. In this direction, the Hoffmann reflex (H-reflex), the electrical homologous of the stretch reflex, has been used in an attempt to better understand how the central nervous system integrates the descending signals with those coming from the periphery, it has been used as an indirect measurement of spinal excitability. This thesis aimed to comprehensively investigate the role of the H-reflex in women with PFP. Firstly, a cross-sectional study was proposed aiming to facilitate the implementation of neurophysiological measures in the clinical setting through the assessment of the tendon reflex (T-reflex) using a simple clinical hammer. Findings from these and other previous studies instigated the authors to raise the hypothesis whether lower H-reflex is a risk factor or a consequence of PFP. In order to answer this question, the authors proposed a 1-year prospective observational cohort study. Given the results presented in this thesis, we understand the contribution of neurophysiological aspects in PFP.<br>Doutor
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Faria, Nathálie Clara Souto [UNESP]. "Análise da modulação do reflexo H do vasto medial em mulheres com síndrome da dor femoropatelar." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/126591.
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000841352.pdf: 682325 bytes, checksum: 20db3128ee36833e584d7212eb120e7f (MD5)<br>Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>A Síndrome da Dor Femoropatelar (SDFP) é uma disfunção musculoesquelética comum na população que apresenta como principal sintoma clínico a dor intermitente nas regiões anterior, peri ou retropatelar, que é exacerbada por atividades funcionais. Embora a SDFP seja de alta incidência, até o presente momento não existem fatores que sejam considerados ideais para caracterização da disfunção. Sabe-se apenas que a SDFP pode levar a alterações eletromiográficas nos músculos Vasto Medial (VM) e Vasto Lateral (VL). Outra informação relevante conhecida é que o processo de controle neuromuscular do músculo quadríceps pode ser analisado através da obtenção do Reflexo H. A hipótese deste estudo é que mulheres com SDFP apresentam modulação do Reflexo H diferente de mulheres assintomáticas. Diante do exposto, o objetivo deste estudo foi analisar a amplitude do Reflexo H em mulheres caracterizadas clinicamente com a SDFP e em mulheres assintomáticas, bem como testar a qualidade da medida utilizada. Foram recrutadas 30 mulheres, sendo 15 com SDFP e 15 assintomáticas, e compuseram o Grupo SDFP (GSDFP) e o Grupo Controle (GC) respectivamente. As medidas pico a pico das amplitudes do Reflexo H máximo (Hmáx), do Reflexo H a 50% da intensidade necessária para atingir o Hmáx (H50%) e da Onda M máxima (Mmáx) foram coletadas, a Mmáx foi o fator de normalização...<br>The Patellofemoral Pain Syndrome (PFPS) is a common musculoskeletal disorder in the population that has as main clinical symptom intermittent pain in the anterior, peri or retropatellar regions, the pain is exacerbated by functional activities. Although PPS is a high incidence, so far there are no factors that are considered ideal for characterization of dysfunction. It is only known that PPS can lead electromyographic changes in the muscles Vastus Medialis (VMO) and Vastus Lateralis (VL). Other relevant information known is that the process of neuromuscular control of the quadriceps muscle can be analyzed by obtaining the H-reflex. The hypothesis of this study is that women with PFPS have different H-reflex modulation from asymptomatic women. The objective of this study was to analyze the amplitude of the H-reflex in women characterized clinically with the PPS and in asymptomatic women, and to test the quality of the measure used. 30 women were recruited, 15 were diagnosed with PFPS and 15 assymptomatic. They composed the PFPS Group (PFPSG) and control group (CG) respectively...
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Faria, Nathálie Clara Souto. "Análise da modulação do reflexo H do vasto medial em mulheres com síndrome da dor femoropatelar /." Presidente Prudente, 2015. http://hdl.handle.net/11449/126591.
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Orientador: Fábio Mícolis de Azevedo<br>Coorientador: Fernando Henrique Magalhães<br>Banca: Rúben de Faria Negrão Filho<br>Banca: Fernando Amâncio Aragão<br>Resumo: A Síndrome da Dor Femoropatelar (SDFP) é uma disfunção musculoesquelética comum na população que apresenta como principal sintoma clínico a dor intermitente nas regiões anterior, peri ou retropatelar, que é exacerbada por atividades funcionais. Embora a SDFP seja de alta incidência, até o presente momento não existem fatores que sejam considerados ideais para caracterização da disfunção. Sabe-se apenas que a SDFP pode levar a alterações eletromiográficas nos músculos Vasto Medial (VM) e Vasto Lateral (VL). Outra informação relevante conhecida é que o processo de controle neuromuscular do músculo quadríceps pode ser analisado através da obtenção do Reflexo H. A hipótese deste estudo é que mulheres com SDFP apresentam modulação do Reflexo H diferente de mulheres assintomáticas. Diante do exposto, o objetivo deste estudo foi analisar a amplitude do Reflexo H em mulheres caracterizadas clinicamente com a SDFP e em mulheres assintomáticas, bem como testar a qualidade da medida utilizada. Foram recrutadas 30 mulheres, sendo 15 com SDFP e 15 assintomáticas, e compuseram o Grupo SDFP (GSDFP) e o Grupo Controle (GC) respectivamente. As medidas pico a pico das amplitudes do Reflexo H máximo (Hmáx), do Reflexo H a 50% da intensidade necessária para atingir o Hmáx (H50%) e da Onda M máxima (Mmáx) foram coletadas, a Mmáx foi o fator de normalização...<br>Abstract: The Patellofemoral Pain Syndrome (PFPS) is a common musculoskeletal disorder in the population that has as main clinical symptom intermittent pain in the anterior, peri or retropatellar regions, the pain is exacerbated by functional activities. Although PPS is a high incidence, so far there are no factors that are considered ideal for characterization of dysfunction. It is only known that PPS can lead electromyographic changes in the muscles Vastus Medialis (VMO) and Vastus Lateralis (VL). Other relevant information known is that the process of neuromuscular control of the quadriceps muscle can be analyzed by obtaining the H-reflex. The hypothesis of this study is that women with PFPS have different H-reflex modulation from asymptomatic women. The objective of this study was to analyze the amplitude of the H-reflex in women characterized clinically with the PPS and in asymptomatic women, and to test the quality of the measure used. 30 women were recruited, 15 were diagnosed with PFPS and 15 assymptomatic. They composed the PFPS Group (PFPSG) and control group (CG) respectively...<br>Mestre
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Hesketh, Kathryn Louise. "Behaviour of H- and cutaneous reflexes at different levels of background muscle activity." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ59816.pdf.
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Lavergne, Pascal de. "Approche(s) de l'imaginaire dans l'oeuvre photographique de J. H. Lartigue : du reflet à la part de l'ombre." Rennes 2, 2000. http://www.theses.fr/2000REN20059.
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La signature de Lartigue invite à reconsidérer son œuvre photographique sous l'angle de l'imaginaire. L'artiste a laissé une œuvre complexe, monumentale, inachevée, qui sollicite notre regard et pose la question de l'imaginaire pour donner à voir les images. Lartigue a vécu sa vie en la rêvant par la photographie, il a inventé une pratique qui ne répond à aucun critère établi : elle correspond à un jeu venu de l'enfance, un secret, un mystère. Comment un corps pris dans un "devenir-photographie" s'exprime-t-il en images ? Dans cette enquête, l'écriture du journal intime apporte un écho déterminant aux albums. Avec Lartigue, la photographie devient un acte de croyance, de foi, de connaissance qui engage le corps dans le temps avec l'image, et donne vie à une Histoire. L'imaginaire se profile à travers une "Image-Mémoire" construite par la photographie, dans l'ombre du père et de la mère. Le geste photographique révèle une recherche du temps perdu dans l'apparaître d'une enfance retrouvée. Notre approche s'inscrit dans une pratique réflexive qui traverse les champs de l'Esthétique et des Arts Plastiques, dans le souci permanent de remonter à la source du système Lartiguien, de l'expérimenter au contact d'une dynamique possible entre philosophie, littérature et cinéma. La notion de montage envisage de reconstituer l'expérience d'un "corps-image ", de décomposer le temps cristallisé, et d'éclairer le processus des métamorphoses. Notre projet vise à ausculter les signes de cette image inclassable, nouvelle et puissante, mélancolique du cinématographe, et à découvrir ses mécanismes internes qui mettent en continuité le mouvement des formes entre les formes<br>Lartigue's signature invites one to reconsider his photographic work from the stand point of the imaginary. Lartigue has left us with an unfinished piece of work which is both extremely complex and monumental and which cannot but catch one's eye and leave one faced with the question of the imaginary. Lartigue dreamed his life through photography: he invented a method which was trail-brazing : it mirrors a childhood game, a secret, a mystery. How does a body express itself in images when taken for a "photograph to be" ? ln this study, reading of his personal diary is of precious importance when trying to comprehend his albums. Photography becomes an act of faith, of belief, of knowledge mingling body and image in time, and giving life to a Story. The imaginary emerges via an "Image-Memory" created by the photograph, with father and mother' s images in the background. The photographic movement is a symbol of the search of times past and of a renewed childhool to brought to life via the magic of photography. Our study is an analysis which brushes through the Esthetic as well as the Plastic Arts, with the ain of going back to the origins of Lartigue' s method of work and to confront it to philosophy, literature and to the cinema. The idea of mounting will enable one to relive the " body-image" experience, to break down time, bring it to a stand still and to enlighten our understanding of the process of metamorphosis. Our project is aimed at studying the marks of this new, powerful and. Melancolic cinematographic work, which cannot be put into any category, and to try and find what internal mechanisms bring in perpetual movement of shapes between shapes
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Borský, Ondřej. "H-reflex při provádění pasivních pohybů." Master's thesis, 2012. http://www.nusl.cz/ntk/nusl-310893.
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Title: Motoneuron excitability depending on the level of muscle stretch Aim: The aim of this thesis is to evaluate if passive muscle lenght change may influence parameters of H - reflex of soleus muscle Method: Tibial nerve stimulation in the fossa poplitea area was performed on 6 persons while passive stretching or lengthening of the muscle. Action potentials were captured on soleus muscle. Stimulation was performed in three different time periods - 4s, 2s, 1s. Each period was performed twice. First in passive muscle stretching then the passive shortening. The Hmax and Mmax values during passive muscle stretching and shortening were evaluated and compared. Results: The measurment results showed that there was a significant decrease in the Hmax values during passive muscle stretching. Mmax values were evaluated as passive muscle length change independent. Keywords: EMG, recruitment curve, H-reflex, M-wave, m.soleus, excitability
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陳永杰. "A computerized electromyography examination system:quantitative analysis of blink reflex and H reflex." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/64721499168482686626.
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碩士<br>逢甲大學<br>自動控制工程學系<br>87<br>The blink reflex and H reflex are widely used in the diagnosis of trigeminal, facial nerve and brain stem disorders as well as C-6 or C-7 and S-1 radiculopathies. However, the latency is not strong evidence to assess the neuropathies because the hemiplegia and hemispheral lesions may have normal latency, but the amplitude or area is abnormal. In order to investigate the pathologies objectively, the main purpose of this research is to develop the quantitative analysis tools for blink and H reflex. The electroacupuncture results showed that a significant difference in late response (R2) latencies (i.e., in comparison with the contralateral R2 latency by stimulating the right supraorbital nerve and the ipsilateral R2 latency by stimulating the left supraorbital nerve) occurred between acupuncture and post-acupuncture. For the hemorrhage in the left thalamus and internal capsule case, the results showed that the ipsilateral area and contralateral area of R2 by stimulating on the right supraorbital nerve were significantly smaller than that of the ipsilateral area and contralateral area of R2 by stimulating on the left supraorbital nerve. Also, the latencies on both sides by stimulating on the right supraorbital nerve were significantly delayed. The evidence demonstrated a significant difference between affected side and unaffected side. For the no corpus callosum case, the R2 areas were significantly smaller than that of the ten normal adult volunteers. In the experimental results of the H reflex, the mean H-M interval change is 25.49ms for 8 normal adults（mean age is 22.6 years and height is 171.8cm), it matches well with the literature data. The quantitative analysis tools not only reflect the disorder of patients based on clinical evaluation, but also provide a standard data for tracking and treating disorder.
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Müller, Katja [Verfasser]. "Untersuchung der Erregbarkeit spinaler Motoneurone während Propofolmononarkosen : H-Reflex und H-Reflex-recovery (interstimulusintervallabhängige Erholung) / von Katja Müller." 2006. http://d-nb.info/978794605/34.
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Stiborová, Pavla. "H-reflex v závislosti na poloze kloubu." Master's thesis, 2010. http://www.nusl.cz/ntk/nusl-299939.
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Title: H-reflex, depending on the position of the joint Aim: The aim of this study is to determine whether the position of the ankle joint influences the parameters of the soleus muscle H-reflex. We are interested in a change of amplitude, latency and threshold of the H-reflex. Method: To measure H-reflex, we have used surface elektromygraphy. We examined two different positions of the foot in probands lying on the bed on their stomach. The first position was with the feet out of bed, around 90 degrees at the ankle joint (rest position). At the second position, the foot moved the bed and was in position in plantar flexion. Stimulation were performed over the tibial nerve in the popliteal fossa. The response, we recorded the surface electrode over the soleus muscle. Results: By changing the position of the ankle from rest to plantar flexion there was no statistically significant changes in amplitude, latency or threshold of the H-reflex. In plantar flection, we found a reduction of Hmax/Mmax ratio, which is probably due to reduced excitability alpha motoneurons through reciprocal ihibition from stretched muscle of the leg. Keywords: H-reflex, soleus muscle, joint position, surface EMG
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Scutter, Sheila Doreen. "H-reflex in human masseter / by Sheila Doreen Scutter." Thesis, 1999. http://hdl.handle.net/2440/19483.
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Copies of author's previously published articles inserted.<br>Bibliography: leaves 172-204.<br>xi, 211 leaves : ill. (some col.) ; 30 cm.<br>H-relexes are used to determine the reflex connections of muscle spindle afferents, the exitability of the motorneuron pool and the integrity of the reflex pathways. However, H-relexes are small and can be difficult to elicit in the masseter, limiting their use in the investigation of the masticatory system. This study investigated the recruitment of masseter motorneurons into the H-reflex, compared to the recruitment occuring during voluntary isometric biting, to determine the distribution of the effective muscle spindle input.<br>Thesis (Ph.D.)--University of Adelaide, Dept. of Physiology, 1999