Dissertations / Theses on the topic 'Muscle mechanics'
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Marcucci, Lorenzo. "A mechanical model of muscle mechanics." Phd thesis, Ecole Polytechnique X, 2009. http://pastel.archives-ouvertes.fr/pastel-00004880.
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Dunaway, Dwayne Lee. "Nano-mechanics of skeletal muscle structures /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8022.
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Sundar, Kartik. "The importance of muscle mechanics during movement." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28137.
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Thesis (M. S.)--Biomedical Engineering, Georgia Institute of Technology, 2009.Committee Chair: DeWeerth, Stephen P.; Committee Co-Chair: Ting, Lena H.; Committee Member: Burkholder, Thomas J.; Committee Member: Nichols, T. Richard; Committee Member: Tresch, Matthew C.
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Roman, Horia Nicolae. "Smooth muscle molecular mechanics in the latch-state." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121358.
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The latch-state is the capacity of smooth muscle to maintain force for long periods of time with low energy consumption. The prevalent theory to explain the latch-state suggests that if myosin gets deactivated (dephosphorylated) while attached to actin, it remains attached and maintains force. Other theories suggest that dephosphorylated and detached myosin can bind to actin to maintain force and that actin regulatory proteins participate in the force maintenance. All theories of the latch-state were based on measurements performed at the whole muscle level and were never confirmed at the molecular level. Verifying the latch-state theories at the molecular level was the main goal of this thesis.To further our understanding of the latch-state, the role of calponin in the binding of unphosphorylated myosin to actin was determined. The laser trap assay was used to measure the average force of unbinding (Funb) in the absence and presence of calponin. Calponin enhanced the Funb. Phosphorylation of calponin with Ca2+-calmodulin dependant protein kinase II, which detaches calponin from actin, decreased the Funb to the unregulated actin level. Performing the measurements at high ionic strength, which detaches calponin from myosin, had the same effect on the Funb. These later two measurements demonstrate that calponin enhances the Funb of unphosphorylated myosin to actin by crosslinking them together. Next, the effect of caldesmon on the Funb was studied; caldesmon enhanced the Funb. Because tropomyosin is known to potentiate biochemical and mechanical effects of caldesmon, its action on the Funb in combination with caldesmon was also measured. Tropomyosin enhanced the Funb on its own but had no synergistic effect with caldesmon. Phosphorylation of caldesmon with the extracellular signal-regulated kinase (ERK) decreased the Funb below the unregulated actin level. Because ERK phosphorylation of caldesmon occurs late in the contraction, this last result suggests a relaxation mechanism from the latch-state. Examination of the force traces revealed a visco-elastic behavior of myosin in the presence of ERK phosphorylated caldesmon which either prevents binding or promotes detachment from actin, thus leading to muscle relaxation. Finally, the ultimate molecular level demonstration of the latch-state requires dephosphorylation of myosin during molecular force measurements with a laser trap assay. However, addition of myosin light chain phosphatase cannot be done without disturbing the single molecule level mechanics measurements. Thus, a microfluidic device was designed and developed to allow the addition of chemicals to a molecular mechanics flow-through chamber without creating any bulk flow. A micro-channel chamber was created by standard photolithography on silicon wafers with the patterns transferred to polymethylsiloxane (PDMS). The chamber was then bound to a polycarbonate membrane which itself was bound to the molecular mechanics chamber. The micro-channels assured rapid distribution of the chemicals whereas the membrane assured efficient delivery but prevented bulk flow. The device was tested by injection of adenosine triphosphate to initiate the propulsion of actin by myosin. The proof of principle of this microfluidic device concludes this thesis.Le muscle lisse possède la capacité unique de maintenir une force élevée tout en consommant peu d'adénosine triphosphate (ATP); cette propriété est appelée 'latch-state'. La théorie la mieux connue pour expliquer cet état suggère que si la myosine est désactivée (déphosphorylation de sa chaîne légère) pendant qu'elle est attachée à l'actine, elle reste attachée et maintient la force. D'autres théories suggèrent que la myosine désactivée et détachée peut s'attacher à l'actine pour maintenir la force et que les protéines régulatrices de l'actine participent aussi à cet effort. Toutes les théories sur l'état 'latch' ont été extrapolées à partir de mesures réalisées sur la totalité du muscle sans jamais être confirmées au niveau moléculaire. Le but principal de cette thèse était de vérifier les théories de l'état 'latch' au niveau moléculaire. Afin de mieux comprendre l'état 'latch', le rôle de la calponine, dans l'attachement de la myosine non-phosphorylée à l'actine, a été déterminé. Des pinces optiques ont été utilisées pour mesurer la force moyenne de leur détachement (Funb) en l'absence et en présence de la calponine. La calponine a augmenté la Funb. La phosphorylation de la calponine avec l'enzyme protéine kinase II (Ca2+-calmoduline dépendante), qui a pour effet de détacher la calponine de l'actine, a diminué la Funb jusqu'au niveau de l'actine non-régulée. De plus, des mesures de force ont été réalisées à haute force ionique, détachant cette fois-ci la calponine de la myosine. Ceci a aussi diminué la Funb jusqu'au niveau de l'actine non-régulée. Ces résultats montrent que la calponine augmente la Funb de la myosine non-phosphorylée à l'actine par liaison croisée (myosine-calponine-actine). Ensuite, l'effet de la caldesmone sur la Funb a été étudié; la caldesmone augmente aussi la Funb. Puisque la tropomyosine est connue pour promouvoir les actions biochimiques et mécaniques de la caldesmone, son action sur la Funb en combinaison avec la caldesmone a aussi été mesurée. La tropomyosine augmente la Funb lorsqu'elle est seule mais n'a pas d'effet synergétique avec la caldesmone. La phosphorylation de la caldesmone avec la kinase régulatrice des signaux extracellulaires (ERK) a diminué la Funb en dessous du niveau de l'actine non-régulée. Ce dernier résultat suggère un mécanisme de relaxation à partir de l'état 'latch' étant donné que la phosphorylation de la caldesmone par ERK se produit tard dans la contraction. D'autre part, l'examen des traces de force a révélé un comportement viscoélastique de la myosine en présence de la caldesmone phosphorylée, ce qui semble soit prévenir l'attachement, soit promouvoir le détachement de l'actine, menant ainsi à la relaxation du muscle à partir de l'état 'latch'. Finalement, la démonstration ultime de l'état 'latch' au niveau moléculaire requiert la déphosphorylation de la myosine pendant les mesures de forces moléculaires faites à l'aide de pinces optiques. Cependant l'addition de la phosphatase de la chaîne légère de myosine ne peut se faire sans perturber les mesures de mécanique au niveau moléculaire. A cet effet, un appareil micro-fluidique a été conçu et développé pour permettre l'ajout de solutions biochimiques à la chambre de mesure de micromécanique sans créer de débit net. Des micro-canaux ont été créés par photolithographie sur substrats de silicium suivie d'un transfert des formes sur polymethylsiloxane (PDMS). La chambre des micro-canaux a ensuite été collée à une membrane de polycarbonate qui elle a ensuite été collée à la chambre de micromécanique. Les micro-canaux assurent la livraison rapide et uniforme tandis que la membrane assure le transfert efficace des produits biochimiques tout en empêchant un débit net. Le fonctionnement de l'appareil a été vérifié en injectant de l'ATP en présence d'actine et de myosine phosphorylée. La propulsion de l'actine par la myosine a été observée validant ainsi le principe de l'appareil microfluidique.
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Bampouras, Theodoros M. "Assessment of muscle activation capacity : methodological considerations of muscle mechanics and implications for testing." Thesis, Manchester Metropolitan University, 2016. http://e-space.mmu.ac.uk/617472/.
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Muscle activation capacity assessment could be affected by the mechanical behaviour of the muscle, but this aspect has received little attention. Understanding the effect the muscle's mechanical behaviour has on muscle activation capacity assessment can be paramount in achieving a better understanding of muscle function. The aim of the present Thesis was to examine the methodological implications of the mechanical behaviour of the muscle during muscle activation capacity assessment. Four studies were designed to examine the effect of the muscle-tendon unit on a) muscle activation capacity calculation methods and number of stimuli used, by manipulating quadriceps muscle length and consequently stiffness, b) stimulation intensity required and associated discomfort, by examining whether a lower than supramaximal stimulation intensity threshold, sufficient to stretch the muscle-tendon, exists, and c) the interplay between muscle mechanics and activation, by manipulating the testing position on the dynamometer, stabilisation and concurrent activation of remote muscles. Isometric knee extensions were used for all studies, and electrical stimuli was delivered to the muscle to quantify muscle activation capacity or induce muscular contractions by circumventing the voluntary neural drive. The results showed that a) altered muscle stiffness affects muscle activation values depending on the calculation method and number of stimuli used, suggesting caution to testing where muscle stiffness is likely to change, b) a lower stimulation intensity exists that can reduce subject discomfort while obtaining valid activation capacity results, widening the application of electrical muscle stimulation, and c) muscle activation must be considered in musculoskeletal models for more accurate predictions but the level of activation will ultimately depend on how stabilised the muscle is. Collectively, these results demonstrate the considerable effect muscle mechanics have on muscle activation capacity and that muscle strength assessment must take into account this aspect for more accurate inferences on muscle function.
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Tomalka, André [Verfasser], and Tobias [Akademischer Betreuer] Siebert. "Determination of biomechanical and architectural muscle properties : from single muscle fibre to whole muscle mechanics / André Tomalka ; Betreuer: Tobias Siebert." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2018. http://d-nb.info/1162497270/34.
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Goddard-Marshall, Ayana A. "Characterization of the activity of the involuntary calf muscle pump." Diss., Online access via UMI:, 2009.
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Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Bioengineering, Biomedical Engineering, 2009.Includes bibliographical references.
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Pontén, Eva. "Tendon transfer mechanics and donor muscle properties : implications in surgical correction of upper limb muscle imbalance." Doctoral thesis, Umeå universitet, Institutionen för integrativ medicinsk biologi (IMB), 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-167.
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Tendon transfer surgery is used to improve the hand function of patients with nerve injuries, spinal cord lesions, cerebral palsy (CP), stroke, or muscle injuries. The tendon of a muscle, usually with function opposite that of the lost muscle function, is transferred to the tendon of the deficient muscle. The aim is to balance the wrist and fingers to achieve better hand function. The position, function, and length at which the donor muscle is sutured is essential for the outcome for the procedure. In these studies the significance of the transferred muscle’s morphology, length and apillarization was investigated using both animal and human models. Immunohistochemical, biochemical, and laser diffraction techniques were used to examine muscle structure. In animal studies (rabbit), the effects of immobilization and of tendon transfers at different muscle lengths were analyzed. Immobilization of highly stretched muscles resulted in fibrosis and aberrant regeneration. A greater pull on the tendon while suturing a tendon transfer resulted in larger sarcomere lengths as measured in vivo. On examination of the number of sarcomeres per muscle fiber and the sarcomere lengths after 3 weeks of immobilization and healing time, we found a cut-off point up to which the sarcomerogenesis was optimal. Transfer at too long sarcomere lengths inhibited adaptation of the muscle to its new length, probably resulting in diminished function. In human studies we defined the sarcomere lengths of a normal human flexor carpi ulnaris muscle through the range of motion, and then again after a routinely performed tendon transfer to the finger extensor. A calculated model illustrated that after a transfer the largest force was predicted to occur with the wrist in extension. Morphological studies of spastic biceps brachii muscle showed, compared with control muscle, smaller fiber areas and higher variability in fiber size. Similar changes were also found in the more spastic wrist flexors comparing with wrist extensors in children with CP. In flexors, more type 2B fibers were found. These observations could all be due to the decreased use in the spastic limb, but might also represent a specific effect of the spasticity. In children and adults with spasticity very small fibers containing developmental myosin were present in all specimens, while none were found in controls. These fibers probably represent newly formed fibers originating from activated satellite cells. Impaired supraspinal control of active motion as well as of spinal reflexes, both typical of upper motor syndrome, could result in minor eccentric injuries of the muscle, causing activation of satellite cells. Spastic biceps muscles had fewer capillaries per cross-sectional area compared to age-matched controls, and also a smaller number of capillaries around each fiber. Nevertheless, the number of capillaries related to the specific fiber area was normal, and hence the spastic fibers are sufficiently supplied with capillaries. This study shows that the length of the muscle during tendon transfer is crucial for optimization of force output. Laser diffraction can be used for accurate measurement of sarcomere length during tendon transfer surgery. Wrist flexor muscles have more morphological alterations typical of spasticity compared to extensors.
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Pontén, Eva. "Tendon transfer mechanics and donor muscle properties : implications in surgical correction of upper limb muscle imbalance /." Umeå : Integrativ medicinsk biologi, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-167.
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Murtada, Sae-Il. "Smooth muscle modeling activation and contraction of contractile units in smooth muscle /." Licentiate thesis, Stockholm : Skolan för teknikvetenskap, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11349.
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Macgregor, Lewis James. "Neuromuscular markers of high performance sport preparation : muscle contractile mechanics." Thesis, University of Stirling, 2016. http://hdl.handle.net/1893/24445.
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Assessments of skeletal muscle functional capacity or bilateral muscular asymmetry often necessitate maximal contractile effort, which exacerbates muscle fatigue or injury. Tensiomyography (TMG) has been investigated in laboratory settings, as a means to assess muscle contractile function following fatigue; however observations have not been contextualised by concurrent physiological measures. TMG has more sparingly been applied in the field, with elite athletes. The aim of this thesis was to examine acute alterations and underlying variations in muscle contractile mechanics, through the application of TMG, contextualised with established physiological measures; and to apply TMG within high performance sports programmes. TMG successfully detected fatigue, evident from reduced strength, by displaying impaired muscle displacement, accompanied by elevated resting muscle tension. Greater asymmetry was detected in individuals with asymmetric strength; however, symmetry was masked during more complex tasks. Increased day-to-day variability was detected among highly trained athletes compared to recreationally active individuals. Acute training adaptations were detected, in contractile mechanics, in individual muscles. TMG could be useful in establishing fatigue status of skeletal muscle without exacerbating the functional decrements of the muscle, whilst also providing useful screening information for detecting asymmetry which may not be apparent during functional actions.
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Vawda, Farouk. "Effects of hydrostatic pressure on single intact muscle fibres." Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294625.
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Dobbie, Ian Michael. "Elastic distortion of cross-bridges and filaments in active and rigor muscle." Thesis, King's College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286289.
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Pamboris, George Michael. "An investigation into the mechanisms of acute effects of dynamic stretching on ankle joint mechanics and running economy." Thesis, Brunel University, 2018. http://bura.brunel.ac.uk/handle/2438/16256.
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Warm-up routines commonly include stretching to increase flexibility (joint range of motion - ROM), optimise performance, and reduce the risk of injury. Literature suggests that static stretching as part of the warm-up routines decreases force and power production compared to an active warm-up or a warm-up including dynamic stretching, and therefore could be detrimental to performance. This has led to an increased interest in the use of dynamic stretching by many athletes while the benefits of such interventions and their potential mechanisms of action are not well understood. Studies presented in this thesis were conducted to examine the effects of acute dynamic stretching on aspects of performance (e.g. torque production capacity of the plantarflexors and running economy) and to identify possible neuromechanical mechanisms underpinning any potential changes. Furthermore, we attempted to examine whether altered pain tolerance/perception to stretch may be a contributing factor to the increased ROM using adaptations in the neural substrates involved by using functional magnetic resonance imaging (fMRI) technique. In the first study, both slow dynamic stretching and fast dynamic stretching increased ROM, and this was due to an increased tendon elongation. Importantly, dynamic stretching was not detrimental to the torque producing capacity of the ankle plantarflexors. Effects of dynamic stretching on the sensorimotor performance remained mainly unclear. Employment of shear wave elastography technique in the second study suggested an increase in muscle stiffness, a decrease in fascicle strain, and showed an increase in muscle thickness after dynamic stretching, supporting an increase in tendon compliance as a contributing factor to increased flexibility after dynamic stretching. In the third study, the improved running economy by dynamic stretching may be attributable to the decreased dynamic joint ankle and vertical stiffness. The fMRI study was not conclusive due to methodological issues. Present findings have practical implications for the use of dynamic stretching in sporting contexts.
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Neil, Thomas Robert. "Muscle mechanics and hydrodynamics of jet propulsion swimming in marine invertebrates." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/15435/.
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Locomotion amongst animals is widespread and diverse. Movement is of fundamental biological importance to animals, enabling them to forage, migrate, pursue prey and mate. Animals have evolved a great range of locomotor mechanisms that span huge size ranges and diversity across the animal kingdom, yet several common principles underlie most of these mechanisms, the understanding of which can help explain why certain biological locomotor systems have evolved for particular environments. Constraints on an animal’s morphological traits are bought about by body size, meaning that several aspects of locomotor performance are found to vary with body mass. Burst performance plays a crucial role in many animals lives, with the ability to accelerate and manoeuvre quickly often being essential for survival. The power available from the muscles during this type of locomotion is generally thought to decrease with increasing body size, with cycle frequency predicted to limit maximal muscle mass-specific performance. Muscle mass-specific power was measured in vivo in scallops covering a 96-fold range in body mass. Power was measured using sonomicrometry crystals to measure muscle length changes during swimming whilst pressure was simultaneously monitored within the mantle cavity. The scaling of the contractile characteristics of the adductor muscles of scallops was investigated to determine what affect the intrinsic properties of the muscle have on the scaling of muscle power output. Muscle fibre bundles were dissected and attached to a force transducer to measure force and muscle length change. Muscles were electrically stimulated via platinum plate electrodes. The scaling of twitch kinetics and the force velocity relationship were characterised in vitro. Jet propulsion via pulsed jets have been shown to be able to produce more thrust per unit of ejected fluid then an equivalent steady jet. The benefit is bought about through the production of isolated vortex rings, which entrain additional ambient fluid into the wake. There are numerous biological swimmers that use jet propulsion as their primary form of locomotion, however, their ability to be able to use vortex rings to enhance their propulsive performance has only been investigated in a few systems. Jet wake structure and swimming performance were quantified in three animals that swim by jet propulsion; scallops, Nautilus and jellyfish. The properties of the wakes were characterised using particle image velocimetry to measure the wake structure of the jets that were produced. Muscle mass-specific power output was found to decrease with increasing size in scallops. Frequency decreased with increasing size, muscle stress was found to be approximately constant whilst muscle strain decreased with increasing size in king scallops. The scaling exponents for muscle power were greater than those of the scaling of cycle frequency, suggesting that cycle frequency is not the sole determinant of the scaling of muscle power output. Muscle power output measured in vitro was also found to decrease with increasing body mass, but scaled with an exponent greater than that measured in vivo. The Vmax of the muscles decreased with increasing size, but did not scale in the same way as cycle frequency, suggesting that the intrinsic contractile properties of the muscle were not the sole determinant of cycle frequency in scallops. King scallops and Nautilus were found to produce two distinct jet modes, one in which isolated vortex rings were produced (Jet mode 1) and one which consisted of a leading vortex ring followed by a trailing jet of fluid (Jet mode 2). No differences were found in jet mode and the thrust produced from the jet, although enhanced thrust was found in king scallops producing jets at formation numbers of ~4. The wake structure of Rhizostomeae jellyfish revealed that they propel themselves via and interaction of two vortex rings that are produced as they swim. They were also found to manipulate the formation of a vortex ring that is formed as they swim, manoeuvring it to within their sub-umbrella cavity, providing them with an additional boost during swimming.
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Barbieri, Fabio Augusto [UNESP]. "Impact of muscle fatigue on mechanics and motor control of walking." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/100450.
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barbieri_fa_dr_rcla.pdf: 481614 bytes, checksum: e57c4e77ba2af478c3789c06447fba99 (MD5)O objetivo do estudo é analisar os efeitos da fadiga muscular na mecânica e controle motor do andar em diferentes ambientes. Uma série de estudos envolvendo fadiga e andar analisaram o impacto da fadiga no andar em diferentes ambientes, as mudanças no controle do andar relacionado com a fadiga muscular, e os efeitos da fadiga em diferentes grupos musculares na mecânica e controle do andar durante descida de degrau. A presente tese mostrou que a fadiga no quadríceps modifica substancialmente o padrão do andar independentemente do ambiente. No andar em ambiente regular, durante a ultrapassagem de obstáculo e durante a descida de obstáculo, a fadiga do quadríceps aumentou a base de suporte e reduziu a duração da passada, mas não modificou o posicionamento dos pés em relação ao obstáculo e ao degrau, melhorando o equilíbrio para evitar quedas. Ainda, a mecânica e o controle durante a última passada antes de descer o degrau e a aterrissagemforam dependenteda fadiga nos músculos do tornozelo ou joelho. Foi encontrado que a articulação usada para absorver a energia cinética na descida do degrau após fadiga dos músculos do tornozelo foi dependente da estratégia de descida usada, contato com o calcanhar ou com o metatarso. No entanto, a variabilidade da distancia horizontal pé-obstáculo da perna de abordagem e de suporte foi maior após ambos os protocolos de fadiga, indicando redução no controle do posicionamento do pé. Além disso, os efeitos da fadiga nos músculos do joelho no andar em ambiente regular e irregular de adultos jovens foram independentes do nível de atividade física, mas com efeito do envelhecimento. As modulações espaço-temporal e cinética nas duas tarefas depois da fadiga dos músculos do joelho iniciaram após a idade de 40 anos com estratégia mais arriscada...
The aim of the study is to analyze the effects of muscle fatigue on mechanics and motor control of walking in different environments. A series of walking experiments addressedmuscle fatigue impact in different gait tasks, age-related changes in control of gait with muscle fatigue, and effects of fatigue in different muscular group on mechanics and control of gait during stepping down. The present thesis showed that quadriceps muscle fatigue modifies gait fairly independent of the environment. In walking on a level surface, during obstacle crossing and during stepping down quadriceps fatigue caused with a wider basis of support and reduced stride duration, but without modulation of placement of the feet in crossing an obstacle and stepping down a curb. This strategyimproves the balance to avoid falling. Furthermore, the mechanics and control during the last stride before stepping down and in landing phase were dependent on whether ankle muscles or knee muscles were fatigued. It should be noted that the joint used to absorb kinetic energy in stepping down with ankle muscle fatigue was dependent on whether a heel or toe landing strategy was used. However, the variability of trailing and leading foot-step horizontal distance was higher after both fatigue protocols, which indicates a reduced control of foot placement. Moreover, the effects of knee muscle fatigue on even and uneven walking of young adults were independent of physical activity level but age-related. The spatial-temporal and kinetic modulations in both tasks after knee muscle fatigue started over 40 years old with a risky strategy for older individuals (over 60 years old). In conclusion: a) knee muscle fatigue affects medio-lateral balance control independently of type of gait, which were compensated by modulation of the spatial-temporal and kinetic parameters, angular... (Complete abstract click electronic access below)
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Barbieri, Fabio Augusto. "Impact of muscle fatigue on mechanics and motor control of walking /." Rio Claro : [s.n.], 2012. http://hdl.handle.net/11449/100450.
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Orientador: Lilian Teresa Bucken GobbiBanca: Jaap H. van Dieën
Banca: Luis Mochizuki
Banca: Quincy Almeida
Banca: Renato de Moraes
Resumo: O objetivo do estudo é analisar os efeitos da fadiga muscular na mecânica e controle motor do andar em diferentes ambientes. Uma série de estudos envolvendo fadiga e andar analisaram o impacto da fadiga no andar em diferentes ambientes, as mudanças no controle do andar relacionado com a fadiga muscular, e os efeitos da fadiga em diferentes grupos musculares na mecânica e controle do andar durante descida de degrau. A presente tese mostrou que a fadiga no quadríceps modifica substancialmente o padrão do andar independentemente do ambiente. No andar em ambiente regular, durante a ultrapassagem de obstáculo e durante a descida de obstáculo, a fadiga do quadríceps aumentou a base de suporte e reduziu a duração da passada, mas não modificou o posicionamento dos pés em relação ao obstáculo e ao degrau, melhorando o equilíbrio para evitar quedas. Ainda, a mecânica e o controle durante a última passada antes de descer o degrau e a aterrissagemforam dependenteda fadiga nos músculos do tornozelo ou joelho. Foi encontrado que a articulação usada para absorver a energia cinética na descida do degrau após fadiga dos músculos do tornozelo foi dependente da estratégia de descida usada, contato com o calcanhar ou com o metatarso. No entanto, a variabilidade da distancia horizontal pé-obstáculo da perna de abordagem e de suporte foi maior após ambos os protocolos de fadiga, indicando redução no controle do posicionamento do pé. Além disso, os efeitos da fadiga nos músculos do joelho no andar em ambiente regular e irregular de adultos jovens foram independentes do nível de atividade física, mas com efeito do envelhecimento. As modulações espaço-temporal e cinética nas duas tarefas depois da fadiga dos músculos do joelho iniciaram após a idade de 40 anos com estratégia mais arriscada... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The aim of the study is to analyze the effects of muscle fatigue on mechanics and motor control of walking in different environments. A series of walking experiments addressedmuscle fatigue impact in different gait tasks, age-related changes in control of gait with muscle fatigue, and effects of fatigue in different muscular group on mechanics and control of gait during stepping down. The present thesis showed that quadriceps muscle fatigue modifies gait fairly independent of the environment. In walking on a level surface, during obstacle crossing and during stepping down quadriceps fatigue caused with a wider basis of support and reduced stride duration, but without modulation of placement of the feet in crossing an obstacle and stepping down a curb. This strategyimproves the balance to avoid falling. Furthermore, the mechanics and control during the last stride before stepping down and in landing phase were dependent on whether ankle muscles or knee muscles were fatigued. It should be noted that the joint used to absorb kinetic energy in stepping down with ankle muscle fatigue was dependent on whether a heel or toe landing strategy was used. However, the variability of trailing and leading foot-step horizontal distance was higher after both fatigue protocols, which indicates a reduced control of foot placement. Moreover, the effects of knee muscle fatigue on even and uneven walking of young adults were independent of physical activity level but age-related. The spatial-temporal and kinetic modulations in both tasks after knee muscle fatigue started over 40 years old with a risky strategy for older individuals (over 60 years old). In conclusion: a) knee muscle fatigue affects medio-lateral balance control independently of type of gait, which were compensated by modulation of the spatial-temporal and kinetic parameters, angular... (Complete abstract click electronic access below)
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Torres-Oviedo, Gelsy. "Robust muscle synergies for postural control." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/22691.
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Thesis (Ph. D.)--Biomedical Engineering, Georgia Institute of Technology, 2007.Committee Chair: Ting, Lena H.; Committee Member: Chang, Young-Hui; Committee Member: Lee, Robert H.; Committee Member: Nichols, T. Richard; Committee Member: Wolf, Steve L.
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Xu, Bo Garner Brian Alan. "A linked-plane obstacle-set algorithm for modeling broad muscle paths application to the deltoid muscle /." Waco, Tex. : Baylor University, 2008. http://hdl.handle.net/2104/5212.
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Gabriel, David Abraham. "Muscle activation patterns for goal-directed multijoint arm movements." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28748.
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The purpose of this dissertation was to determine if the CNS produces relatively simple alterations in muscle activity to accomplish goal-directed reaching motions of the upper limb under a variety of movement conditions.To this end, six subjects performed goal-directed arm movements in the horizontal plane. Two movement amplitudes (300 mm and 400 mm) were completed at a moderate speed (1050 mm/s) and as-fast-as possible. The speed and amplitude conditions were repeated for the 45$ sp circ$ and 90$ sp circ$ movement directions. Finally, each of the movement conditions mentioned thus far, were performed within the right and left sections of the work-space. Surface electro-myographic activity was recorded from the pectoralis major, posterior deltoid, biceps brachii short head, brachioradialis, triceps brachii long head, and triceps brachii lateral head. Motion recordings were obtained with a spatial imaging system that monitored the positions of infrared emitting diodes attached to the subject's upper arm and forearm-hand complex.
Several simplification schemes were found to be operative at the level of the electro-myogram. These include: (a) simple timing relationships for agonists between joints and agonist/antagonist intermuscle latencies within each joint; (b) tightly coupled timing between agonists within a single joint; (c) for a particular movement direction, the form and shape of EMG burst activity followed a strategy associated with modulation of pulse height and width; (d) the slope, duration, and onset were further affected by the direction of hand movement which resulted in the greatest RMS-EMG signal amplitude, changing in a predictable manner, and finally (e) there was tuning in which elbow muscles were activated earlier for goal-directed arm movements in the left area of the work-space.
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Miller, Zachary Dalton. "Tensile Properties of Single Vaginal Smooth Muscle Cells." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83567.
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Improving treatment and prevention of pelvic organ prolapse, a disorder affecting up to half of parous women, requires thorough mechanical analysis of the vagina and other endopelvic structures at the cellular level. In this study, we tested single vaginal smooth muscle cells (SMCs) to quantify their elastic moduli. Cells were enzymatically isolated from vaginal walls of freshly sacrificed, virgin Long Evans rats and cultured using well-established methods. A custom-built experimental setup was used to perform tensile tests. Micropipettes were fabricated to serve as cantilever-type load cells, which were coated in cellular adhesive. Two pipettes applied tension to SMCs until adhesion between the cell and a pipette failed. During mechanical testing, images of SMCs were collected and translated into strain and stress. Specifically, force/stress data were calculated using Euler-Bernoulli Beam Theory and by making simplifying geometric assumptions. The average initial and total elastic moduli (mean ± SEM) for single vaginal SMCs were 6.06 ± 0.26 kPa and 5.4 ± 0.24 kPa, respectively, which is within the range reported for other types of SMCs, mainly airway and vascular, of various species. This protocol can and will be applied to further investigate mechanics of single cells from the pelvic region with independent variables such as parity, age, body mass index, and various stages of POP. Results of these experiments will provide critical information for improving current treatments like drug therapies, surgical procedures, medical grafts and implants, and preventative practices like stretching and exercise techniques.Master of Science
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Moore, Isabel Sarah. "Running self-optimisation : acute and short-term adaptations to running mechanics and running economy." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/13622.
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The intuitive link between a runner’s gait and their metabolic cost of running, or running economy (RE), has led to many trying to compare the running mechanics of economical runners to those of less economical runners. However using this approach has created controversy about whether running mechanics meaningfully contribute to RE. Additionally only a limited number of studies use a broad, explorative, inter-disciplinary approach, encompassing physiological parameters, flexibility, kinematics, kinetics and muscular activity. The purpose of this thesis was to primarily assess ‘self-optimisation’ through considering acute and short-term adaptations to running mechanics and RE. To assess the biomechanical and physiological mechanisms behind changes to RE three studies were conducted, in addition to a fourth study which investigated biomechanical familiarisation. Study one investigated whether there were any biomechanical or physiological changes in beginner runners after 10 weeks of running and whether any of these changes contributed to a change in RE. There was an 8.4% improvement in RE (224 24 vs. 205 27 mL.kg-1.min-1) and an increase in treadmill time-to-exhaustion (16.4 3.2 vs. 17.3 2.7 min), but no change in ̇ 2max, minute ventilation or heart rate. Several kinematic, kinetic and flexibility measures were found to change over time, but joint moments and stiffness remained similar, with knee extension at toe-off, rearfoot velocity at touch down and timing of peak dorsiflexion explaining 94.3% of the variance in change in RE. Results from study one suggested that changes in muscular activity might have contributed to kinematic differences, and subsequently an economical gait. Specifically, as joint moments were unchanged after 10 weeks it is possible that muscular coactivation may have changed since varying levels of agonist-antagonist activation can produce the same joint moment. Consequently study two examined the relationship between muscular coactivation and the metabolic cost of running, as thus far there was conflicting evidence. Results showed that in trained, recreational runners greater thigh coactivation was associated with a greater metabolic cost of running. Furthermore, the speed of running was found to affect the level of coactivation at the shank and of the flexor-flexor muscle pair, with less coactivation reported at faster submaximal speeds. The final part of the thesis focused on a manipulation investigation into barefoot (BFT), minimalist shod (MS) and shod (SH) running. Applying the novel findings from studies one and two to this topical area would hopefully provide new insight into the 3 BFT running debate. Prior to applying this knowledge of kinematic and muscular activity changes in relation to RE whilst running BFT, an investigation into the time required to become familiar with barefoot treadmill running was needed. Results revealed that barefoot familiarisation was characterised by less plantarflexion and greater knee flexion at touch down, whilst stride length appeared to be adopted instantaneously. Reliability (intra-class correlations) and accuracy (standard error of mean) of the kinematic data appeared strongest once individuals had been running for 20 mins. Furthermore there were no significant differences in the kinematics after 20 mins of running. The final study considered how changing the levels of proprioception and cushioning (BFT, MS and SH) influenced RE and the potential running mechanics that contributed to any changes in RE. The ramifications of such changes on injury risk were also considered by investigating impact accelerations, effective mass and pronation. Additionally, the effect of naturally changing stride length from a shorter BFT stride to a longer SH stride on RE were examined. Heightened proprioception and no external cushioning (BFT running) appeared to improve RE by at least 5% regardless of stride length, when compared to SH running with a SH stride length. However less proprioception and no external cushioning (MS running) only improves RE, compared to SH running with a SH stride length, when runners run with their SH stride length, rather than their shorter BFT stride length (~2.5% shorter). Improvements in RE are attributed to a lower vertical oscillation and effective mass, greater dependency on efficient, Type I muscles i.e. tibialis anterior, and less plantarflexion at toe-off. However higher impact accelerations, earlier heel off and low pronation angles, suggest there may be an increase in injury risk. Therefore the findings from this thesis have demonstrated that runners naturally selfoptimise the way they run. This is seen both as an acute (changes in footwear) and short-term (10 weeks) response to changing running gait. Study two demonstrated that economical runners appear to use different muscular strategies, with study one and four showing they also adopt specific movement patterns that may promote efficient storage and release of elastic energy. Additionally study three found that runners can become familiar with BFT treadmill running in 20 minutes. It is also important to note that economical biomechanical adjustments do not always favour a reduction in injury risk. But the thesis findings seem to suggest that perhaps performance denominates in terms of self-optimisation, rather than injury prevention.
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Maganaris, Constantinos N. "In vivo mechanics of the human maximum isometric voluntary contraction : implications for musculoskeletal modelling." Thesis, Manchester Metropolitan University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267446.
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Spinner, Erin M. "Tricuspid valve mechanics: understanding the effect of annular dilatation and papillary muscle displacement." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45754.
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Tricuspid regurgitation (TR), back flow of blood from the right ventricle to the right atrium, has been reported in approximately 85% of the population, with 16% having mild or severe TR. Patients with untreated moderate to severe TR are likely to experience decreased exercise capacity and have increased morbidity and mortality, thus affecting the patient's quality of life. Current methods of repair offer limited rates of success, and many patients require further operations to correct returning levels of TR. Incomplete repair may be due to incomplete understanding of the functional anatomy and mechanics of the TV and the underlying causes of TR.
It was hypothesized that alterations in the geometry of tricuspid valve annular and subvalvular apparatus induced by ventricular dilatation determine the severity of TR. In vivo measurements of papillary muscle (PM) position in patients with single or biventricular dilatation revealed PM displacement away from the center of the annulus as compared to control patients. Additionally, pulmonary arterial pressure, annulus area, ventricular size and apical displacement of the anterior PM were highly correlated with the severity of TR. An in vitro right-heart simulator was developed to investigate isolated mechanics of TR. Through these in vitro studies it was demonstrated that the tricuspid valve begins to leak at only 40% dilation, much lower than the mitral valve. Additionally, it was shown that isolated PM displacement resulted in significant TR. The highest levels of TR were achieved with a combination of annular dilatation and PM displacement. Alterations in leaflet coaptation, as quantified by measuring the amount of leaflet available for coaptation and leaflet mobility were observed with annular dilatation and PM displacement, both isolated and combined. The changes in leaflet coaptation resulted in redistribution of the forces on the chords originating from the anterior PM and inserting into the anterior and posterior leaflets.
The findings herein provide the clinical and scientific community with a mechanistic understanding of the tricuspid valve to further improve intervention and repair of TV disease.
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Iliffe, Cathryn Ann. "The kinetics and mechanics of myosin and subfragment-1 from insect flight muscle." Thesis, University of York, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251800.
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Wang, Ruoli. "Biomechanical Consequences of Foot and Ankle Injury and Deformity: Kinematics and Muscle Function." Licentiate thesis, Stockholm : Royal Institute for Technology, School of Engineering Sciences, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11217.
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Gutierrez, Elena M. "Gait strategy in myelomeningocele : movements, mechanics, and methods /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-644-8/.
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Quintero, Kevin E. "Modeling Adjustable Passive Stiffness in Detrusor Smooth Muscle." VCU Scholars Compass, 2006. http://scholarscompass.vcu.edu/etd_retro/130.
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Passive detrusor smooth muscle exhibits both viscoelastic softening and strain softening. Strain softening is a loss of stiffness following a stretch to a longer length and is reversible upon muscle activation. Because of this behavior, steady state passive force in detrusor is not constant for a given muscle length and can be adjusted by an intracellular mechanism. Thus, passive detrusor exhibits adjustable passive stiffness. Existing three-component mechanical models for muscle, the Kelvin and Voigt, are insufficient to display this characteristic. The goal of this thesis is to develop a new biomechanical model for passive force in detrusor by adding additional elements to the Kelvin or Voigt models. Eight mechanical characteristics of detrusor are identified from the literature and with three new experiments, and a novel adjustable passive stiffness model for smooth muscle is proposed. Simulations are performed to demonstrate that the model qualitatively exhibits each of the eight tissue characteristics.
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Johnson, Timothy John. "The influence of temperature on the mechanics and energetics of contraction in fish muscle." Thesis, University of St Andrews, 1991. http://hdl.handle.net/10023/15049.
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Chapter 1. A general introduction into the adaptation of teleost fish to changing thermal environments. The underlying mechanisms at all levels of organization are reviewed in relation to adaptive change over evolutionary and seasonal time-scales. Chapter 2. 1. The contractile properties of swimming muscles have been investigated in marine teleosts from Antarctic (Trematomus lepidorhinus, Pseudochaenichthys georgianus), temperate (Pollachius virens. Limanda limanda. Agonis cataphractus. Callionymus lyra) and tropical (Abudefduf abdominalis, Thalassoma duperrevi) latitudes. 2. Small bundles of fast twitch fibres were isolated from anterior myotomes and/or the pectoral fin adductor profundis muscle (m.add.p). Live fibre preparations were viable for several days at in vivo temperatures, but became progressively inexcitable at higher or lower temperatures. The stimulation frequency required to produce fused isometric tetani increased from 50Hz in Antarctic species at 0°C to around 400 Hz in tropical species at 25°C. Maximum isometric tension (P0) was produced at the normal body temperature (NBT) of each species (Antarctic, 0-2°C; North Sea and Atlantic, 8-10°C; Indo-West Pacific, 23-25°C). P0 values at physiological temperatures (200-300 kN m-2) were similar for Antarctic, temperate and tropical species. 3. A temperature induced "tension hysteresis" was observed in muscle fibres from the temperate and Antarctic species. Chapter 3. 1. Fast and slow muscle fibres were isolated from the myotomes of atlantic cod (Gadus morhua L.) and short-horned sculpin (Myoxocephalus scorpius L.). 2. Epinephrine was found to have no effect on twitch or sub-tetanic contractions in fast muscle fibres. 3. Isoprenaline (10-6M) had no effect on the contractility of slow muscle fibres. 4. In contrast, epinephrine elicited a dose-dependent decrease in the half-time for twitch relaxation (t1/2r), and in most cases a decrease in twitch amplitude. Chapter 4. 1. Fast muscle fibres were isolated from the abdominal myotomes of the short-horned sculpin, Myoxocephalus scorpius L. Sinusoidal length changes were imposed about resting muscle length and fibres stimulated at a selected phase during the strain cycle. The work output per cycle was calculated from the area of the resulting force- position loops. Chapter 5. 1. Bundles of 20-30 fast muscle fibres were isolated from the abdominal myotomes of the short-horned sculpin (Myoxocephalus scorpius L.). 2. The energy cost of contraction was measured during oscillatory work at 4°C and 15°C following treatment with iodoacetate and nitrogen gas to block glycolysis and aerobic metabolism. 3. Isolated fibres were subjected to sinusoidal length changes about in situ resting length and stimulated at a selected phase in the strain cycle. Preliminary experiments with untreated preparations established the strain amplitude and stimulation parameters required to maximize work output over a range of cycle frequencies at 4°C and 15°C. Chapter 6. The results of the thesis are discussed, particularly in relation to their evolutionary and locomotory significance. From the principles and ideas formulated, future lines of research are suggested.
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Léguillette, Renaud. "Expression of smooth muscle myosin heavy chain isoforms in asthma and their molecular mechanics." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103169.
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Two smooth muscle (SM) myosin heavy chain isoforms, generated by alternative mRNA splicing, differ by the presence (SM-B) or absence (SM-A) of a 7 amino acid insert in the motor domain. The rate of actin filament propulsion (nu max) of SM-B, as measured in the in vitro motility assay, is 2-fold greater than that of SM-A. I investigated the expression and function of these isoforms in healthy SM and in asthma. First, I determined the sequence of the SM-B isoform in human SM and quantified its expression at the mRNA and protein levels in several human organs. The SM-B isoform was mostly expressed in rapidly contracting phasic SM. I then purified myosin from multiple rat organs and found a rank correlation between SM-B content and numax.I then quantified the expression of SM-B and several other contractile protein genes in endobronchial biopsies from normal and asthmatic subjects. SM-B, myosin light chain kinase (MLCK), which is responsible for myosin activation, and transgelin, a ubiquitously expressed actin binding protein but whose function is unknown, were overexpressed in the asthmatic biopsies. The increased SM-B expression and myosin activation, due to the increased MLCK expression, both contribute to the increased rate of shortening of the asthmatic airway SM. In addition, I showed that beyond its enzymatic effects, MLCK mechanically enhances numax. The binding of SM22 to actin, however, did not alter numax.
Finally, I addressed the mechanisms behind the unique capacity of SM to maintain force at low energy cost, namely the latch-state. This property is mostly observed in SM-A containing, tonic muscle. Using a laser trap, I measured the binding force of unphosphorylated (non-active) SM-A and SM-B myosin isoforms and found that they can both attach to actin and maintain force. I also measured numax at different MgADP concentrations and found that SM-A has a greater affinity for MgADP. Because MgADP must be released before myosin can detach from actin, these results suggest that the SMA isoform remains attached longer to actin, allowing it to get into the latch-state. These findings explain the greater propensity of tonic muscle to get into the latch-state.
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de, Winter J. M., B. Joureau, V. Sequeira, N. F. Clarke, der Velden J. van, G. J. Stienen, H. Granzier, A. H. Beggs, and C. A. Ottenheijm. "Effect of levosimendan on the contractility of muscle fibers from nemaline myopathy patients with mutations in the nebulin gene." BioMed Central, 2015. http://hdl.handle.net/10150/610333.
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BACKGROUND: Nemaline myopathy (NM), the most common non-dystrophic congenital myopathy, is characterized by generalized skeletal muscle weakness, often from birth. To date, no therapy exists that enhances the contractile strength of muscles of NM patients. Mutations in NEB, encoding the giant protein nebulin, are the most common cause of NM. The pathophysiology of muscle weakness in NM patients with NEB mutations (NEB-NM) includes a lower calcium-sensitivity of force generation. We propose that the lower calcium-sensitivity of force generation in NEB-NM offers a therapeutic target. Levosimendan is a calcium sensitizer that is approved for use in humans and has been developed to target cardiac muscle fibers. It exerts its effect through binding to slow skeletal/cardiac troponin C. As slow skeletal/cardiac troponin C is also the dominant troponin C isoform in slow-twitch skeletal muscle fibers, we hypothesized that levosimendan improves slow-twitch muscle fiber strength at submaximal levels of activation in patients with NEB-NM. METHODS: To test whether levosimendan affects force production, permeabilized slow-twitch muscle fibers isolated from biopsies of NEB-NM patients and controls were exposed to levosimendan and the force response was measured. RESULTS: No effect of levosimendan on muscle fiber force in NEB-NM and control skeletal muscle fibers was found, both at a submaximal calcium level using incremental levosimendan concentrations, and at incremental calcium concentrations in the presence of levosimendan. In contrast, levosimendan did significantly increase the calcium-sensitivity of force in human single cardiomyocytes. Protein analysis confirmed that the slow skeletal/cardiac troponin C isoform was present in the skeletal muscle fibers tested. CONCLUSIONS: These findings indicate that levosimendan does not improve the contractility in human skeletal muscle fibers, and do not provide rationale for using levosimendan as a therapeutic to restore muscle weakness in NEB-NM patients. We stress the importance of searching for compounds that improve the calcium-sensitivity of force generation of slow-twitch muscle fibers. Such compounds provide an appealing approach to restore muscle force in patients with NEB-NM, and also in patients with other neuromuscular disorders.
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Wahl, Joel. "Development of Methods to Investigate Pulmonary Arterial Smooth Muscle Cells under Hypoxia." Licentiate thesis, Luleå tekniska universitet, Strömningslära och experimentell mekanik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-77140.
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Hypoxic pulmonary vasoconstriction (HPV) is a physiological response to localized alveolarhypoxia that is intrinsic to the pulmonary circulation. By hypoxia-induced contractionof pulmonary arterial smooth muscle cells (PASMCs), the pulmonary capillary bloodflow is redirected to alveolar areas of high oxygen partial pressure, thus maintaining theventilation-perfusion ratio. Although the principle of HPV was recognized decades agothe underlying pathway remains elusive. The patch clamp technique, imaging and Ramanspectroscopy are methods that can be used to investigate parts of the mechanisms. Toenable measurements at controlled oxygen concentrations a gas-tight microfluidic systemwas developed. In this thesis preparatory experiments to couple the gas-tight systemto a microscope that enabled simultaneous measurements with patch clamp, imagingand Raman spectroscopy are discussed. The patch clamp technique is to be used formeasurements on the dynamics of the ion-channels in the cellular membrane as well aschanges in membrane potential as a response to hypoxia. Imaging of PASMCs is requiredto successfully apply the patch clamp technique. Further, imaging will also reveal whetherthe mechanical response of HPV has been triggered, for this purpose image analysis forestimation of optical flow can be used. Raman spectroscopy enables measurements ofbiochemical changes in redox biomarkers, cytochrome c and NADH, of the mitochondrialelectron transport chain. This thesis shows that the gas-tight microfluidic system providesoptimal control of the oxygen content, in an experimantal setting where the patch clamptechnique can be applied. Raman measurements showed significantly larger variationsin spectra compared to an open fluidic system, which is the conventional approach.However, the results showed a need for improved Raman preprocessing. For this purposea Convolutional Neural Network (CNN) was trained using synthetic spectra that providedoptimal reconstruction of the Raman signal. Finally, simultaneous imaging and Ramanspectroscopy of red blood cells were performed in a home built microscope. The resultspave the way for measurements on PASMCs.
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Carson, Melissa Catherine. "The mobility and stability of the human metatarsophalangeal joint of the hallux." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365692.
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Almasri, Atheer. "MECHANICAL BEHAVIOR AND LENGTH ADAPTATION OF RABBIT BLADDER SMOOTH MUSCLE." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1967.
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Overactive bladder (OAB), involuntary contractions during bladder filling, is a common condition affecting 17% of the adult population worldwide, and in the U.S. ranks ahead of diabetes in a list of the 10 most common chronic disorders (Mullins 2009). Mechanical mechanisms contributing to OAB are not completely understood and because of the unique function and broad volume range of the bladder, there may be mechanical characteristics that distinguish detrusor smooth muscle (DSM) in bladder from other smooth muscles. Recent studies have shown that the length-passive tension curve in DSM exhibits adjustable passive stiffness (APS) characterized by a passive curve that can be shifted along the length axis as a function of strain history and activation history; however, the mechanical mechanisms responsible for APS remain to be determined. Also, whether DSM exhibits a dynamic length-active tension relationship, as has been identified in airway and vascular smooth muscles, has not been investigated. This dissertation focused on both the passive and active length-tension relationships in DSM and the mechanical mechanisms responsible for these relationships. The first objective was to study the impact of APS on the length-total tension relationship and identify the mechanical mechanisms responsible for generating APS. The second objective was to determine whether the length-active tension relationship is adaptive and identify specific mechanical mechanisms contributing to any adaptive behavior. The results showed that a shift in the length-passive tension curve due to APS corresponded with a shift in the length-total tension curve in DSM, and that APS was 27.0±8.4% of active tension at the optimum length for active tension generation. Most importantly, low-grade rhythmic contraction (RC), which can occur spontaneously in rabbit and human bladders, regenerated APS. Results also showed that the length-active tension curve shifted due to stretch to and then activation at long lengths, as well as either multiple KCl-induced maximal contractions or RC. Thus, DSM exhibits length adaptation, and RC may contribute to both APS and length adaptation. Because increased RC has been correlated with OAB, understanding RC, APS and length-adaptation in bladder may enable the identification of specific targets for new treatments for OAB.
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Long, Benjamin L. DeVita Paul 1955. "Muscle work discrepancy during incline and decline running at three speeds." [Greenville, N.C.] : East Carolina University, 2009. http://hdl.handle.net/10342/1863.
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Thesis (M.S.)--East Carolina University, 2009.Presented to the faculty of the Department of Exercise and Sport Science. Advisor: Paul DeVita. Title from PDF t.p. (viewed May 4, 2010). Includes bibliographical references.
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Kimmig, François. "Multi-scale modeling of muscle contraction : From stochastic dynamics of molecular motors to continuum mechanics." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLX071/document.
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L'objectif de cette thèse est la modélisation mathématique des mécanismes de contraction musculaire à l'échelle microscopique dans le but de proposer et d'intégrer ces modèles dans un environnement de simulation cardiaque multi-échelle.Ce travail est réalisé dans le contexte de la médecine numérique, qui propose d'améliorer le traitement des patients par l'utilisation d'outils numériques.La première contribution de cette thèse est une analyse bibliographique des travaux expérimentaux caractérisant l’interaction actine-myosine et ses régulations afin de compiler les informations sous une forme utilisable pour le développement de modèles.Cette étape est une condition préalable essentielle à la modélisation.Nous proposons ensuite une hiérarchie de modèles de contraction musculaire à partir d'un modèle stochastique raffiné existant, mais validé uniquement pour les muscles squelettiques, en appliquant des hypothèses de simplification successives.Les étapes de simplification transforment l'équation différentielle stochastique initiale en une équation aux dérivées partielles avec une description qui fait partie de la famille de modèles dérivée du modèle Huxley'57.Une simplification supplémentaire conduit ensuite à un modèle décrit par un ensemble d'équations différentielles ordinaires.La pertinence des modèles proposés, qui ciblent différentes échelles de temps, est démontrée en les comparant aux données expérimentales obtenues avec des muscles cardiaques, et leur domaine de validité est étudié.Pour intégrer ces descriptions dans un environnement de simulation cardiaque, nous avons étendu ces modèles afin de prendre en compte les mécanismes de régulation de la force qui se produisent in vivo.Cela conduit à de nouvelles équations aux dérivées partielles.Ensuite, nous lions les modèles de contraction microscopiques à un modèle d’organe macroscopique.Nous suivons pour cela une approche fondée sur les principes thermodynamiques pour traiter la nature multi-échelle en temps et en espace du tissu musculaire aux niveaux continu et discret.La validité de cet environnement de simulation est démontrée en présentant sa capacité à reproduire le comportement du coeur et en particulier les caractéristiques essentielles de l'effet Frank-StarlingThis PhD thesis deals with the mathematical description of the micro-scale muscle contraction mechanisms with the aim of proposing and integrating our models into a multiscale heart simulation framework.This research effort is made in the context of digital medicine, which proposes to improve the treatment of patients with the use of numerical tools.The first contribution of this thesis is a literature review of the experimental works characterizing the actin-myosin interaction and its regulations to compile information in a useable form for the development of models.This stage is an essential prerequisite to modeling.We then propose a hierarchy of muscle contraction models starting from a previously proposed refined stochastic model, which was only validated for skeletal muscles, and applying successive simplification assumptions.The simplification stages transform the initial stochastic differential equation into a partial differential equation with a model that is part of the Huxley'57 model family.A further simplification then leads to a description governed by a set of ordinary differential equations.The relevance of these models, targeting different time scales, is demonstrated by comparing them with experimental data obtained with cardiac muscles and their range of validity is investigated.To integrate these microscopic descriptions into a heart simulation framework, we extend the models to take into account the force regulation mechanisms that take place in vivo, leading to the derivation of new partial differential equations.Then, we link the microscopic contraction models to the macroscopic organ model.We follow for that an approach based on the thermodynamical principles to deal with the multi-scale nature in time and space of the muscle tissue at the continuous and at the discrete levels.The validity of this simulation framework is demonstrated by showing its ability to reproduce the heart behavior and in particular to capture the essential features of the Frank-Starling effect
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Karst, Gregory Mark. "Multijoint arm movements: Predictions and observations regarding initial muscle activity at the shoulder and elbow." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184920.
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Understanding the control strategies that underlie multijoint limb movements is important to researchers in motor control, robotics, and medicine. Due to dynamic interactions between limb segments, choosing appropriate muscle activations for initiating multijoint arm movements is a complex problem, and the rules by which the nervous system makes such choices are not yet understood. The aim of the dissertation studies was to evaluate some proposed initiation rules based on their ability to correctly predict which shoulder and elbow muscles initiated planar, two-joint arm movements in various directions. Kinematic and electromyographic data were collected from thirteen subjects during pointing movements involving shoulder and elbow rotations in the horizontal plane. One of the rules tested, which is based on statics, predicted that the initial muscle activity at each joint is chosen such that the hand exerts an initial force in the direction of the target, while another rule, based on dynamics, predicted initial muscle activity such that the initial acceleration of the hand is directed toward the target. For both rules, the data contradict the predicted initial shoulder muscle activity for certain movement directions. Moreover, the effects of added inertial loads predicted by the latter rule were not observed when a 1.8 kg mass was added to the limb. The results indicated, however, that empirically derived rules, based on ψ, the target direction relative to the distal segment, could predict which muscles would be chosen to initiate movement in a given direction. Furthermore, the relative timing and magnitude of initial muscle activity at the shoulder and elbow varied systematically with ψ. Thus, the target direction relative to the forearm may be an important variable in determining initial muscle activations for multijoint arm movements. These findings suggest a control scheme for movement initiation in which simple rules suffice to launch the hand in the approximate direction of the target by first specifying a basic motor output pattern, then modulating the relative timing and magnitude of that pattern.
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Jeffery, Jay Melvin. "Quantifying the strain response in the rat tibia during simulated resistance training used as a disuse countermeasure." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2087.
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Gras, Laure-Lise. "Caractérisation du comportement mécanique du muscle à différentes vitesses de sollicitation." Phd thesis, Paris, ENSAM, 2011. http://pastel.archives-ouvertes.fr/pastel-00651874.
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Des modèles numériques de l'être humain sont développés pour améliorer la protection des usagers des transports. Pour être réalistes, ces modèles ont besoin de données sur les propriétés géométriques et mécaniques de chaque composant du corps humain, comme les muscles. Cependant, la connaissance des propriétés musculaires pour différents chargements est encore partielle. Pour compléter ces données, un essai de traction quasistatique in vitro a été réalisé pour évaluer les propriétés mécaniques passives sur muscles humains. Un modèle en éléments finis personnalisé géométriquement a été conçu et les paramètres d'une loi hyper-viscoélastique ont été identifiés par méthode inverse. L'influence du taux de déformation sur la réponse passive du muscle en traction a aussi été étudiée. Des paramètres biomécaniques ont été mesurés et un modèle exponentiel a été proposé pour modéliser la réponse effort-déplacement du muscle. La vitesse a un effet sur l'effort maximal atteint, sur la raideur du muscle en fin de chargement et sur le paramètre de courbure. Comme ces expérimentations ont été réalisées in vitro, les conditions expérimentales sont éloignées des conditions physiologiques. Or cet environnement peut affecter la réponse du muscle. Pour évaluer l'effet des conditions d'expérimentation, un essai de traction sur muscles d'un modèle animal a été conduit pour trois environnements : air libre, solution saline froide et solution saline chauffée. Les propriétés mécaniques du muscle sont sensibles aux changements de milieu, plus particulièrement lorsque le muscle passe de l'air libre à l'immersion. En perspectives de ce travail, les propriétés mécaniques identifiées seront introduites dans un modèle en éléments finis du segment corporel tête-cou. Enfin, le muscle étant une structure fibreuse complexe, une modélisation en éléments discrets a été proposée pour lier propriétés microscopiques et propriétés macroscopiques.
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Caruel, Matthieu. "Mechanics of Fast Force Recovery in striated muscles." Phd thesis, Ecole Polytechnique X, 2011. http://pastel.archives-ouvertes.fr/pastel-00668301.
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Cette thèse est consacrée à la modélisation de la réponse transitoire d'une fibre musculaire squelettique soumise à des sollicitations mécaniques rapides. A l'échelle du nanomètre, la fibre musculaire contient des filaments d'actine et de myosine regroupés en unités contractiles appelées "sarcomères". Le filament de myosine est un assemblage de moteurs mol ́eculaires qui, en présence d'ATP, s'attachent et se d ́etachent p ́eriodiquement au filament d'actine. Au cours de ce processus d'attachement-détachement, la myosine génère une force lors d'un changement de conformation appelé "power-stroke". Ses caractéristiques peuvent être étudiées lors de la réponse transitoire de la fibre soumise à des sollicitations mécaniques rapides. Nous proposons un modèle mécanique innovant du demi-sarcomere permettant de relier les caractéristiques de la myosine à la réponse de la fibre complète. A la différence des modèles existants, privilégiant une approche discrète, ce modèle s'appuie sur la définition d'un potentiel d'énergie continu qui prend en compte une interaction de champ moyen entre les moteurs moléculaires. Ce système présente des réponses radicallement différentes à longueur imposée et à force imposée. Nous proposons en particulier une explication à la différence de cinétique observée expérimentalement. Nous montrons également que le demi-sarcomere est m ́ecaniquement instable ce qui explique les inhomogénéités de longueurs observées dans une myofibrille.
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Wilgeroth, J. M. "On the behaviour of porcine adipose and skeletal muscle tissues under shock compression." Thesis, Cranfield University, 2014. http://dspace.lib.cranfield.ac.uk/handle/1826/8527.
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The response of porcine adipose and skeletal muscle tissues to shock compression has been investigated using the plate-impact technique in conjunction with manganin foil pressure gauge diagnostics. This approach has allowed for measurement of the levels of uniaxial stress imparted to both skeletal muscle and rendered adipose tissue by the shock. In addition, the lateral stress component generated within adipose tissue during shock loading has also been investigated. The techniques employed in this study have allowed for equation-of-state relationships to be established for the investigated materials, highlighting non-hydrodynamic behaviour in each type of tissue over the range of investigated impact conditions. While the adipose tissue selected in this work has been shown to strengthen with impact stress in a manner similar to that seen to occur in polymeric materials, the skeletal muscle tissues exhibited a ow strength, or resistance to compression, that was independent of impact stress. Both the response of the adipose material and tested skeletal muscle tissues lie in contrast with the shock response of ballistic gelatin, which has previously been shown to exhibit hydrodynamic behaviour under equivalent loading conditions. Plate-impact experiments have also been used to investigate the shock response of a homogenized variant of one of the investigated muscle tissues. In the homogenized samples, the natural structure of skeletal muscle tissue, i.e. a fibrous and anisotropic composite, was heavily disrupted and the resulting material was milled into a fine paste. Rather than matching the response of the unaltered tissues, the datapoints generated from this type of experiment were seen to collapse back on to the hydrodynamic response predicted for skeletal muscle by its linear equation-of-state (Us = 1.72 + 1.88up). This suggests that the resistance to compression apparent in the data obtained for the virgin tissues was a direct result of the interaction of the shock with the quasi-organized structure of skeletal muscle. A soft-capture system has been developed in order to facilitate post-shock analysis of skeletal muscle tissue and to ascertain the effects of shock loading upon the structure of the material. The system was designed to deliver a one-dimensional, at-topped shock pulse to the sample prior to release. The overall design of the system was aided by use of the non-linear and explicit hydrocode ANSYSR AUTODYN. Following shock compression, sections of tissue were imaged using a transmission electron microscope (TEM). Both an auxetic-like response and large-scale disruption to the I-band/Z-disk regions within the tissue's structure were observed. Notably, these mechanisms have been noted to occur as a result of hydrostatic compression of skeletal muscle within the literature.
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Leib, Daniel J. "The effects of cleat placement of muscle mechanics and metabolic efficiency in prolonged sub-maximal cycling." CardinalScholar 1.0, 2008. http://liblink.bsu.edu/uhtbin/catkey/1427389.
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This study quantified the changes in pedaling mechanics and energy expenditure accompanying a posterior shift in cleat placement during prolonged cycling. Six male competitive cyclists participated. Each subject was asked to complete two separate hour long rides using traditional cleat placement and a novel heel placement, respectively. Expired gasses, kinematics, and EMG from 7 lower limb muscles were collected at three time intervals during each ride. No significant difference in O2 utilization was seen (p=0.905). A significant difference was seen in sagittal plane knee angle (p=0.008) and angular velocity (p=0.003) in the heel condition, demonstrating a more extended knee and lower peaks in angular velocity. Musculo-tendon kinematic data showed no differences. Tibialis anterior (TA) iEMG was higher in the heel condition, and SOL and TA showed differences in timing between conditions. These results demonstrate changes in ankling patterns and knee joint kinematics as adaptations to heel pedaling.School of Physical Education, Sport, and Exercise Science
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Barratt, Paul. "Mechanical muscle properties and intermuscular coordination in maximal and submaximal cycling : theoretical and practical implications." Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/9856.
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The ability of an individual to perform a functional movement is determined by a range of mechanical properties including the force and power producing capabilities of muscle, and the interplay of force and power outputs between different muscle groups (intermuscular coordination). Cycling presents an ideal experimental model to investigate these factors as it is an ecologically valid multi-joint movement in which kinematics and resistances can be tightly controlled. The overall goal of this thesis was thereby to investigate mechanical muscle properties and intermuscular coordination during maximal and submaximal cycling. The specific research objectives were (a) to determine the contribution of these factors to maximal and submaximal cycling, and (b) to determine the extent to which these factors set the limit of performance in maximal cycling. The contribution of mechanical muscle properties and intermuscular coordination were investigated by observing joint kinetics and joint kinematics across variations in crank lengths and pedalling rates during maximal and submaximal cycling. The extent to which these factors set the limit of performance in maximal cycling was assessed by observing joint-level kinetics of world-class track sprint cyclists. The findings of this investigation formed the rationale for the fourth study which used an ankle brace intervention to investigate the effects of a fixed ankle on joint biomechanics and performance during maximal cycling. Sophisticated intermuscular coordination strategies were observed in both submaximal and maximal cycling, supporting the generalised notion that high levels of intermuscular coordination are required to perform functional multi-joint movement tasks. Furthermore, it was found that the maximal cycling task is governed by the interaction of the force-velocity relationship and excitation-relaxation kinetics, suggesting that task-specific mechanical muscle properties are the dominant contributing factor in maximal movements. In terms of the extent to which these factors limit performance in maximal cycling, it was demonstrated that world-class track sprint cycling performance is governed by the ability to generate higher joint moments at the ankle and knee, and that these joint moments are facilitated by enhanced muscular strength about these joints. These findings allow us to speculate that the limits of performance in maximal human movements lie in extraordinary muscular strength in task-specific joint actions. These findings give an insight into the mechanisms that underpin maximal and submaximal cycling, and provide a theoretical framework with which to understand sprint cycling performance. This knowledge has significant applied relevance for athletes and coaches seeking to improve sprint cycling performance.
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Baptista, Rafael Reimann. "Adaptações neuromecânicas ao treinamento de força utilizando ações excênctricas e concêntricas em idosos saudáveis do sexo masculino." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/39084.
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O objetivo deste estudo foi comparar o efeito de um programa de treinamento excêntrico versus concêntrico nas propriedades morfológicas, mecânicas e mioelétricas da unidade músculo-tendão do quadríceps de idosos. Vinte e três sujeitos do sexo masculino (62,74±2,20 anos de idade, 80,21±14,82 kg de massa corporal e 172,02±6,11 cm de estatura) participaram de um programa de treinamento de força durante 12 semanas, duas vezes por semana, realizando extensão unilateral concêntrica em uma articulação do joelho e flexão unilateral excêntrica na articulação do joelho contralateral, a 80% de 5 Repetições Máximas (5 RM). O tratamento estatístico foi composto por teste t de Student nas comparações das diferenças obtidas entre o período pré versus pós treinamento e por ANOVA de dois fatores para comparar as diferenças entre os treinamentos concêntrico versus excêntrico nos dois períodos (pré-treinamento versus pós-treinamento), utilizando o programa de estatística GraphPad Instat versão 3.06, adotando-se um nível de significância de 5%. Nas articulações treinadas excentricamente a força medida pelo teste de 5 RM aumentou de forma significativa (p<0,05) ao longo do programa de treinamento de força, enquanto que com o treinamento concêntrico houve um aumento da força nas primeiras 6 semanas (p<0,05) que não se repetiu nas últimas 6 semanas de treinamento. Avaliando a arquitetura do músculo vasto lateral por meio da ultrassonografia (ALOKA SSD 4000), verificamos que ambos os tipos de treinamento causaram uma redução no comprimento dos fascículos e um aumento no ângulo de penação (p<0,05) sem diferença entre os tipos de treinamento e sem alterar significativamente a espessura muscular (p>0,05). Ao utilizar a ultrassonografia para avaliar a arquitetura do tendão patelar, verificamos um aumento no comprimento do tendão com os dois tipos de treinamento e um aumento na área de seção transversa do tendão apenas da articulação treinada excentricamente (p<0,05). Utilizando um dinamômetro isocinético (Biodex System 3 PRO) verificamos que tanto o treinamento concêntrico quanto o treinamento excêntrico causaram um aumento significativo do torque articular nos ângulos de 50, 60, 70 e 90° (p<0,05), mas não no ângulo de 30° (p>0,05). Adicionalmente, verificamos que o treinamento concêntrico causou um aumento significativo nas velocidades articulares de -240, -180, -120 e -60°/seg e nas velocidades de 180 e 240°/seg (p<0,05). Já o treinamento excêntrico causou um aumento significativo apenas nas velocidades de 60, 120 e 180°/seg, tanto positivas quanto negativas (p<0,05). Utilizando a eletromiografia (Bortec Medical Systems) para comparação da ativação muscular não encontramos diferença significativa em nenhuma das análises. Nossos resultados nos permitem concluir que no que tange a arquitetura muscular o treinamento concêntrico e excêntrico proporcionam adaptações muito semelhantes, enquanto que na arquitetura tendinosa isso é válido para o comprimento muscular, mas não para a área de seção transversa. Todavia o treinamento excêntrico parece trazer um aumento de força mais consistente ao longo do treinamento, ainda que nas propriedades mecânicas não tenha sido constatadas diferenças significativas entre os tipos de treinamento. No que diz respeito as propriedades mioelétricas não encontramos diferenças significativas nas adaptações tanto ao treinamento concêntrico quando excêntrico.The purpose of this study was to compare the effects of an eccentric training versus a concentric training concerning the morphological, mechanical and mioelectric properties of the muscle-tendon unit of the quadriceps muscle in older men. Twenty three male subjects (62.74±2.20 years old, 80.21±14.82 kg of body mass and 172.02±6.11 cm height) have participated of a strength training program for 12 weeks, two times a week, performing unilateral concentric extension of one knee joint and unilateral eccentric flexion of the other knee joint, at 80% of 5RM. The statistica analyses was perfomed by Student t test to compare the differences obtained between the pre-training versus post-training period and by two-way ANOVA to compare the diferences obtained between the concentric versus eccentric training in both periods (pre-training versus post-training) using the statistical software GraphPad Instat version 3.06 assuming a 5% level of significance. On the eccentrically trained joints the strength measured by the 5RM tests increased significantly (p<0.05) during the strength training program, while with the concentric training there was an increase in strength on the first 6 weeks (p<0.05) that didn’t repeat on the last 6 weeks of training. Through the evaluation of the muscle architecture of the vast lateral muscle (ALOKA SSD 4000), we verified that both types of training have caused a shortening of the fascicle length and an increase of the penation angle (p<0.05) without differences between the types of training and without altering significantly the muscle width (p>0.05). When we used the ultrasonography to evaluate the architecture of the patellar tendon, we have verified an increase on the tendon length with both types of training and an increase of the cross-sectional area of the tendon only on the joint trained eccentrically (p<0.05). Using an isokinetic dynamometer (Biodex System 3 PRO) we verified that both the concentric and the eccentric training have caused a significant increase of the joint torque in the angles of 50°, 60°, 70° and 90° (p<0.05), but not in the angle of 30° (p>0.05). Additionally, we verified that the concentric training did cause a significant joint speed increase of -240°, -180°, -120° and -60°/sec and on the speeds of 180° and 240°/sec (p<0.05). In the case of the eccentric training, it caused a significant increase only on the speeds of 60°, 120° and 180°/sec, both positive and negative (p<0.05). Using the electromyography (Bortec Medical Systems) to compare the muscle activation of the vast lateral in different joint angles in the pre and post concentric training periods, we have not verified significant difference in any of the analysis. Our results allow us to conclude that concerning the muscle architecture, concentric and eccentric training produce very similar adaptations, whereas in the tendon architecture this is valid for the muscle length, but not for the cross-sectional area. However, the eccentric training seems to bring a more consistent gain in strength during the training, despite that on the mechanical properties there were no significant differences stated between the types of training. Concerning to the myoelectrical properties we were not able to find any significant adaptation either in concentric or eccentric training.
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Dechert, Melissa A. "Signaling through p21-activated kinase 1 in airway smooth muscle /." abstract and full text PDF (UNR users only), 2002. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3090865.
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Zhang, Hongbo. "Use of Statistical Mechanics Methods to Assess the Effects of Localized muscle fatigue on Stability during Upright Stance." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/30888.
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Human postural control is a complex process, but that is critical to understand in order to reduce the prevalence of occupational falls. Localized muscle fatigue (LMF), altered sensory input, and inter-individual differences (e.g. age and gender) have been shown to influence postural control, and numerous methods have been developed in order to quantify such effects. Recently, methods based on statistical mechanics have become popular, and when applied to center of pressure (COP) data, appear to provide new information regarding the postural control system. This study addresses in particular the stabilogram diffusion and Hurst exponent methods. An existing dataset was employed, in which sway during quiet stance was measured under different visual and surface compliance conditions, among both genders and different age groups, as well as before and after induction of localized muscle fatigue at the ankle, knee, torso, and shoulder.
The stabilogram diffusion method determines both short-term and long-term diffusion coefficients, which correspond to open- and closed-loop control of posture, respectively. To do so, a â critical pointâ (or critical time interval) needs to be determined to distinguish between the two diffusion regions. Several limitations are inherent in existing methods to determine this critical point. To address this, a new algorithm was developed, based on a wavelet transform of COP data. The new algorithm is able to detect local maxima over specified frequency bands within COP data; therefore it can identify postural control mechanisms correspondent to those frequency bands.
Results showed that older adults had smaller critical time intervals, and indicating that sway control of older adults was essentially different from young adults. Diffusion coefficients show that among young adults, torso LMF significantly compromised sway stability. In contrast, older adults appeared more resistance to LMF. Similar to earlier work, vision was found to play a crucial role in maintaining sway stability, and that stability was worse under eyes-closed (EC) than eyes-opened (EO) conditions. It was also found that the short-term Hurst exponent was not successful at detecting the effects of LMF on sway stability, likely because of a small sample size. The new critical point identification algorithm was verified to have better sensitivity and reliability than the traditional approach. The new algorithm can be used in future work to aid in the assessment of postural control and the mechanisms underlying this control.Master of Science
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Chapman, Dale W. "The effect of eccentric exercise velocity on selected measures of muscle function and soreness of the Human elbow flexors in untrained males and females." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2003. https://ro.ecu.edu.au/theses/1485.
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Eccentric contractions, where a muscle is repeatedly lengthened while generating torque, result in decreased muscle function and muscle soreness. This study was designed to determine whether there was a difference in muscle response of the elbow flexors from untrained subjects (n = 12) between a bout of high intensity eccentric exercise at 30°•s-1 (LVE) compared to the equivalent at 210°•s-1 (HVE). Subjects performed 120 seconds of eccentric exercise of the elbow flexors using a Cybex 6000 Isokinetic Dynamometer. At 30°-s-1, a total of 30 repetitions were required whilst at 210°•s-1, 210 contractions were performed (at a 1:7 work/rest ratio). Both exercise bouts resulted in significant decrements in isometric and dynamic strength measures (p
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Alahmari, Sami Khaloufah M. "Muscle force production and neuromuscular fatigue responses to neuromuscular electrical stimulation and tendon vibration." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/236174/1/Sami_Alahmari_Thesis.pdf.
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Neuromuscular electrical stimulation is an intervention that produces artificial muscle contractions and is used to rehabilitate people with motor impairments. However, a typical problem is the occurrence of rapid fatigue, which limits the training stimulus. This thesis investigated whether the addition of tendon vibration and concurrent activation of upper limb muscles could minimise fatigue and maximise torque produced by the calf muscles during neuromuscular electrical stimulation. The experiments in this thesis showed that superimposition of tendon vibration can increase the amount of torque produced by calf muscles, and that the addition of sustained handgrip contraction could further increase this torque.
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Kosterina, Natalia. "Muscular force production during non-isometric contractions : towards numerical muscle modeling /." Licentiate thesis, Stockholm : Skolan för teknikvetenskap, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10672.
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Vahedipour, Annie. "gait.mp4." Diss., Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/508528.
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BioengineeringPh.D.
Locomotion is essential to survival in most animals. Studies have shown that animals, including humans, choose a gait that minimizes the risk of injury and maximizes energetic efficiency. Individuals often encounter obstacles and perturbations during normal locomotion, from which they must recover. Despite the importance of understanding the mechanisms that enable recovery from perturbations, ethical and experimental challenges have prevented full exploration of these in legged systems. A powerful paradigm with which to tackle this difficulty would be the application of external and internal manipulation of the nervous system. These perturbations could target how gait is regulated and how the neural systems process sensory information to control locomotion during an unexpected perturbation. Here we present data on the response of female mice to rapid, precisely timed, and spatially confined mechanical perturbations applied by a treadmill system. Our data elucidate that after the mechanical perturbation, the mouse gait response is anisotropic, preferring deviations away from the trot towards bounding, over those towards other gaits, such as walk or pace. We quantified this shift by projecting the observed gait onto the line between trot and bound, in the space of quadrupedal gaits. We call this projection λ. For λ=0, the gait is the ideal trot; for λ=±π, it is the ideal bound. We found that the substrate perturbation caused a significant shift in λ towards bound during the stride in which the perturbation occurred and the following stride (linear mixed effects model: Δλ=0.26±0.07 and Δλ=0.21±0.07, respectively; random effect for animal, p<0.05 for both strides, n = 8 mice). We hypothesize that this is because the bounding gait is better suited to rapid acceleration or deceleration, and an exploratory analysis of jerk showed that it was significantly correlated with λ (p<0.05). To evaluate whether the same structure of gait controller exists when undergoing an entirely different class of manipulation, we applied an internal, neuromuscular perturbation. We directly stimulated the lateral gastrocnemius muscle of mice using implanted electrodes and a custom magnetic headstage. We found that the electrical muscle stimulation caused a significant shift in λ towards bound in trials where the stimulation occurred during the swing phase (linear mixed effects model: Δλ=0.23±0.06 and Δλ=0.28±0.06; for the stride during and after the stimulation, respectively; random effect for animal, p<0.05 for both, n = 7 mice). Understanding how gait is controlled under perturbations can give insight into the neuromechanical basis of locomotion, aid in diagnosing gait pathologies, and aid the design of more agile robots.
Temple University--Theses