The purpose of this study was to examine changes in muscle ultrastructure and strength performance following a single bout of elbow flexor resistance exercise. Eight untrained males performed 8 sets of 8 repetitions at 80% concentric 1 RM. One arm performed only the concentric (CON) phase of the movement while the other performed only the eccentric (ECC) phase. Maximum isometric (MVC), low (LV} and high velocity (HV} concentric peak torque, and evoked contractile property measurements of the elbow flexors were made before and after the bout, and at 24, 48, 72 and 96 h. Needle biopsies were obtained from the biceps brachii prior to the exercise, immediately post-exercise from each arm (POSTCON, POST-ECC}, and 48 h post-exercise from each arm (48H-CON, 48H-ECC). Electron microscopy was used to quantify the extent of fiber disruption in each sample. The severity of disruption was classified as focal (FOC}, moderate (MOD}, or extreme (EXT}. All strength measurements decreased (P s; o. 05} below pre-exercise values immediately post-ex in both arms, but dramatic differences were observed between arms during the subsequent recovery period. MVC, LV, HV and peak twitch torque (PTT) recovered to pre-ex values by 24 h in the CON arm. In the ECC arm, HV did not recover for at least 72 h, and MVC, LV and PTT remained depressed at 96 h. ANOVA revealed a greater (P s; 0.05) number fibers were disrupted in the POST-CON, POST-ECC, 48H-CON and 48H-ECC samples compared to BASE. Significantly more fibers appeared disrupted in the POST-ECC (82%) and 48H-ECC (80%) samples compared to the POSTCON (33%) and 48H-CON (37%) samples, respectively. In addition, the POST-ECC (41%) and 48H-ECC (50%) samples contained a greater number of fibers with EXT disruption compared to the POST-CON (13%) and 48H-CON (17%) samples. Decreases in MVC at 48 h correlated (P ~ 0.05) with the extent of EXT disruption in the 48H-CON and 48H-ECC samples. These data indicate that both the CON and ECC phase of weightlifting produce myofibrillar disruption, with the greatest disruption occurring during the ECC phase. This study was supported by the Natural Sciences and Engineering Research Council of Canada. / Thesis / Master of Science (MSc)

No description available.

Muscle spindles are skeletal muscle mechanoreceptors that mediate the stretch reflex and provide axial and limb position information to the central nervous system. They have been proposed to play a major role in the pathophysiology of muscle pain. Knowledge about the normal human muscle spindles is needed in order to understand their role in muscle disease or dysfunction. The aim of this study was to investigate the fiber content and MyHC composition of the muscle spindles in the human biceps brachii (BB) and deep muscles of the neck (DN); to determine whether there are age-related changes in human muscle spindles with respect to structure and MyHC composition; to investigate the distribution of SERCA isoforms and to evaluate whether there is a coordinated expression of SERCA and MyHC isoforms in intrafusal fibers. The myosin heavy chain (MyHC) content correlates to contraction velocity and force and the sarcoplasmic reticulum Ca2+ ATPase (SERCA) is a major determinant of muscle fiber relaxation velocity. Muscle specimens obtained from young and old subjects were serially sectioned and the pattern of distribution of different proteins along the length of the intrafusal fibers was revealed by immunocytochemistry. The MyHC content of single muscle spindles was assessed with SDS-PAGE and immunoblots. There were clear differences between BB and DN with regard to the morphology and MyHC composition of muscle spindles. Virtually each muscle spindle in the BB, but not in the DN, had a unique allotment of numbers of bag1, bag2 and chain fibers. In DN, a number of muscle spindles lacked either bag1 or bag2 fibers. Four major MyHC isoforms (MyHCI, IIa, α-cardiac and intrafusal) were detected by SDS-PAGE. In both BB and DN, immunocytochemistry revealed co-expression of several MyHC isoforms in each intrafusal fiber and regional heterogeneity. Both nuclear bag1 and bag2 fibers contained slow tonic MyHC uniformly and MyHCI, α-cardiac, embryonic and fetal with regional variations. Nuclear chain fibers contained MyHCIIa, embryonic and fetal and in the BB also MyHCIIx. The total number of intrafusal fibers per spindle decreased significantly with aging, due to a significant reduction in the number of nuclear chain fibers. The patterns of MyHC expression were also affected by aging. The bag1 fibers predominantly contained both SERCA isoforms in the encapsulated region. The bag2 fibers were more heterogeneous in their SERCA composition and 16-27% of them lacked both isoforms. Chain fibers contained SERCA1. There was a poor correlation between the MyHC and SERCA isoforms in nuclear bag fibers, whereas a strong correlation existed between MyHCIIa and SERCA1 in the nuclear chain fibers. Human muscle spindles, each being unique, proved to be more complex than anticipated. The clear differences shown between the BB and DN muscle spindles suggest functional specialization in the control of movement among different human muscles. Aging apparently had profound effects on intrafusal fiber content and MyHC composition. The age-related changes in muscle spindle phenotype may reflect deterioration in sensory and motor innervation and are likely to have a detrimental impact on motor control in the elderly.

El objetivo general del trabajo fue realizar aportaciones al conocimiento dinamométrico y electromiográfico de la articulación del codo. Para ello se analizó la fuerza isométrica máxima y su variabilidad inter e intraobservador, así como el comportamiento electromiográfico de bíceps y tríceps en diferentes ejercicios dinámicos sobre una población de 23 sujetos sanos. Se determinó también la influencia del género y de la dominancia. Los resultados de las mediciones dinamométricas mostraron valores más altos de fuerza isométrica en los varones, observándose una alta correlación con la talla y el peso corporal. Un CCI>0.71 en todas las mediciones demostró la fiabilidad y reproductibilidad de este método a 90º de flexión. No se encontraron diferencias en cuanto a la lateralidad. La actividad EMGs aumentó con la carga e intensidad del ejercicio dinámico, principalmente en el bíceps. Se demostró la gran influencia del sexo y la dominancia sobre los resultados. / The aim of this study was to make contributions to the knowledge of isometric dynamometry and surface electromyography of the elbow joint. We analyzed the maximal isometric force and inter-intraobserver variability also the electromyographic behavior of biceps and triceps brachii in different dynamic exercises on a population of 23 healthy people. We determined the influence of gender and dominance too. Dynamometric measurements showed higher values of isometric strength in men, showing a high correlation with height and body weight. An ICC>0.71 for all measurements demonstrated the reliability and reproducibility of this method at 90º of elbow flexion. There were no differences between dominant and nondominant side. The sEMG activity increased with the load and intensity of dynamic exercise mainly in the biceps brachii. It showed the great influence of sex and dominance on the results.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-05-31T14:03:18Z No. of bitstreams: 1 felipecostaalvim.pdf: 1024726 bytes, checksum: 960e31300fb235185572e16e58bf4a19 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-02T12:42:12Z (GMT) No. of bitstreams: 1 felipecostaalvim.pdf: 1024726 bytes, checksum: 960e31300fb235185572e16e58bf4a19 (MD5) / Made available in DSpace on 2016-07-02T12:42:12Z (GMT). No. of bitstreams: 1 felipecostaalvim.pdf: 1024726 bytes, checksum: 960e31300fb235185572e16e58bf4a19 (MD5) Previous issue date: 2012-03-30 / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Introdução: O sistema nervoso central (SNC) utiliza o recrutamento de unidades motoras e a modulação da frequência de ativação dessas unidades para controlar a força voluntária exercida por um músculo. A eletromiografia de superfície (sEMG) pode ser utilizada para captar o sinal elétrico resultante do somatório dos potenciais de ação das fibras musculares recrutadas durante o processo de produção de força. A análise da variável root mean square (RMS) e da frequência mediana (Fm) tem sido utilizada para extrair informações a respeito dos mecanismos de controle da força utilizados pelo SNC. Objetivos: Investigar as propriedades do sinal eletromiográfico de indivíduos adultos através das variáveis RMS, Fm e da análise da distribuição da potência por faixas de frequência em contrações isométricas para os níveis de força iguais a 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% e 90% da contração isométrica voluntária máxima (CIVM). Metodogia: Os sinais eletromiográficos foram obtidos a partir da contração isométrica voluntária do bíceps braquial de vinte voluntários jovens saudáveis bilateralmente nos níveis submáximos de força. Um algoritmo foi elaborado visando identificar o trecho ideal do sinal eletromiográfico a ser analisado. As variáveis RMS, Fm e a densidade de potências por faixa de 5 Hz e 10 Hz foram calculadas. Resultados e discussão: A variável RMS apresentou aumento linear com o incremento da força, conforme esperado. A variável Fm apresentou aumento entre 10% e 30% da CIVM e diminuiu para níveis de força superiores. Esse comportamento pode estar relacionado ao protocolo experimental conforme indicado na literatura. A análise da densidade de potência por faixa mostrou uma concentração da densidade de potência na faixa entre 40 e 50 Hz em 10% da CIVM. Essa concentração de potência diminuiu progressivamente em 20% e 30% do nível de força e voltou a ocorrer, na mesma faixa de frequência, em 40% da CIVM. Esse comportamento pode estar relacionado ao acréscimo de fibras de contração dos tipos IIa e IIb ao processo produção de força. Entre 40 e 90% da CIVM a concentração de potência na faixa entre 40 e 50 Hz diminui. Conclusões: As variáveis extraídas do sinal eletromiográfico apresentaram comportamento compatível com o descrito na literatura em protocolos contendo contrações em diversos níveis submáximos da CIVM. Suas variações podem estar relacionadas a diferenças no protocolo experimental. A análise da densidade de potência por faixa de frequências pode trazer informações adicionais estando relacionadas ao processo de recrutamento e ativação das unidades motoras durante o incremento de força. / Introduction: Central nervous system (CNS) uses the motor unit recruitment and the rate coding of the recruited units to control the voluntary force exerted by a muscle. Surface electromyography (sEMG) can be used to capture the electrical signal resulting from the summation of the action potentials of the muscle fibers recruited during the force production. The analysis of the variable root mean square (RMS) and median frequency (Fm) has been used to extract information about the control mechanisms of force used by the CNS. Objectives: To investigate the properties of the electromyographic signal through RMS and Fm variables and analyze the power density distribution in frequency bands in isometric force levels equal to 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% and 90% of maximal voluntary isometric contraction (MIVC). Methods: The signals were obtained bilaterally from the isometric contraction of the biceps brachii muscle of twenty young healthy volunteers in submaximals force levels. An algorithm was developed to identify the ideal section of the electromyographic signal to be analyzed. The variable RMS, Fm and power density distribution in frequency bands of 5 Hz and 10 Hz were calculated. Results and discussion: The variable RMS increased linearly with increasing force, as expected. The variable Fm had increased between 10% and 30% MVIC and than decreased toward high force levels. This behavior can be related to the experimental protocol as described in the literature. The analysis of the power density distribution in frequency bands showed a concentration of power density in the range between 40 Hz and 50 Hz in 10% MIVC. This power density concentration progressively reduced in 20% to 30% of the MIVC and occurs again on the same frequency range in 40% MVIC. This behavior may be related to increased fibers type IIa and IIb to the force production process. From 40% to 90% of the MIVC the concentration in power density in range between 40 Hz and 50 Hz decreases. Conclusions: The variables extracted from the EMG signal showed behavior compatible with the protocols described in the literature containing submaximal contractions at different levels of MIVC. Their variations may be related to differences in experimental protocol. The analysis of power density distribution in frequency bands can provide additional information being related to the recruitment and rate coding of motor units during the increase in voluntary force.

No description available.

Les prothèses myoélectriques modernes peuvent être dotées de plusieurs degrés de liberté ce qui nécessite plusieurs signaux musculaires pour en exploiter pleinement les capacités. Pour obtenir plus de signaux, il nous a semblé prometteur d'expérimenter si les 6 compartiments du biceps brachial pouvaient être mis sous tension de façon volontaire et obtenir ainsi 6 signaux de contrôle au lieu d'un seul comme actuellement. Des expériences ont donc été réalisées avec 10 sujets normaux. Des matrices d'électrodes ont été placées en surface au-dessus du chef court et long du biceps pour recueillir les signaux électromyographiques (EMG) générés par le muscle lors de contractions effectuées alors que les sujets étaient soit assis, le coude droit fléchi ~ 100 ° ou debout avec le bras droit tendu à l'horizontale dans le plan coronal (sur le côté). Dans ces deux positions, la main était soit en supination, soit en position neutre, soit en pronation. L'amplitude des signaux captés au-dessus du chef court du muscle a été comparée à ceux obtenus à partir du chef long. Pour visualiser la forme du biceps sous les électrodes l'imagerie ultrasonore a été utilisée. En fonction de la tâche à accomplir, l'activité EMG a était plus importante soit dans un chef ou dans l'autre. Le fait de pouvoir activer préférentiellement l'un des 2 chefs du biceps, même si ce n'est pas encore de façon complètement indépendante, suggère que l'utilisation sélective des compartiments pourrait être une avenue possible pour faciliter le contrôle des prothèses myoélectriques du membre supérieur. / The latest myoelectric prostheses have several degrees of freedom and therefore require a large number of myoelectric signals to fully exploit their capabilities. Muscle compartments, which are intra-muscular subdivisions innervated by an individual muscle nerve branch, can be exploited to provide additional independent muscle control sites to operate such prostheses. This research presents a work to investigate the activation of the 6 biceps brachii compartments in healthy subjects to see if they have the ability to activate those compartments voluntarily. Therefore, electromyographic (EMG) signals were recorded from an array of seven and ten pairs of equally spaced surface electrodes positioned across the short and long head of the biceps of ten healthy subjects. The EMG signals are collected in two positions: 1) with the subject seated, right elbow flexed ~100°, and 2) with the subject standing with the right arm extended horizontally in the coronal plane (90°shoulder abduction). In both positions, the hand is either fully supinated, neutral, or fully pronated. The average root mean square value of the EMG signals obtained from the pairs of electrodes positioned over the short head are compared with the average obtained for the other pairs placed over the biceps long head. Ultrasound imaging also used to visualize the long and short heads of the biceps in flexed and extended arm while the hand was in different postures. Depending on the task to be accomplished, activity was larger in one head or in the other. Being able to activate either head of the biceps, while not yet completely independently, suggests that the selective use of compartments could be a possible avenue for controlling upper limb myoelectric prostheses.

Les prothèses myoélectriques modernes peuvent être dotées de plusieurs degrés de liberté ce qui nécessite plusieurs signaux musculaires pour en exploiter pleinement les capacités. Pour obtenir plus de signaux, il nous a semblé prometteur d'expérimenter si les 6 compartiments du biceps brachial pouvaient être mis sous tension de façon volontaire et obtenir ainsi 6 signaux de contrôle au lieu d'un seul comme actuellement. Des expériences ont donc été réalisées avec 10 sujets normaux. Des matrices d'électrodes ont été placées en surface au-dessus du chef court et long du biceps pour recueillir les signaux électromyographiques (EMG) générés par le muscle lors de contractions effectuées alors que les sujets étaient soit assis, le coude droit fléchi ~ 100 ° ou debout avec le bras droit tendu à l'horizontale dans le plan coronal (sur le côté). Dans ces deux positions, la main était soit en supination, soit en position neutre, soit en pronation. L'amplitude des signaux captés au-dessus du chef court du muscle a été comparée à ceux obtenus à partir du chef long. Pour visualiser la forme du biceps sous les électrodes l'imagerie ultrasonore a été utilisée. En fonction de la tâche à accomplir, l'activité EMG a était plus importante soit dans un chef ou dans l'autre. Le fait de pouvoir activer préférentiellement l'un des 2 chefs du biceps, même si ce n'est pas encore de façon complètement indépendante, suggère que l'utilisation sélective des compartiments pourrait être une avenue possible pour faciliter le contrôle des prothèses myoélectriques du membre supérieur. / The latest myoelectric prostheses have several degrees of freedom and therefore require a large number of myoelectric signals to fully exploit their capabilities. Muscle compartments, which are intra-muscular subdivisions innervated by an individual muscle nerve branch, can be exploited to provide additional independent muscle control sites to operate such prostheses. This research presents a work to investigate the activation of the 6 biceps brachii compartments in healthy subjects to see if they have the ability to activate those compartments voluntarily. Therefore, electromyographic (EMG) signals were recorded from an array of seven and ten pairs of equally spaced surface electrodes positioned across the short and long head of the biceps of ten healthy subjects. The EMG signals are collected in two positions: 1) with the subject seated, right elbow flexed ~100°, and 2) with the subject standing with the right arm extended horizontally in the coronal plane (90°shoulder abduction). In both positions, the hand is either fully supinated, neutral, or fully pronated. The average root mean square value of the EMG signals obtained from the pairs of electrodes positioned over the short head are compared with the average obtained for the other pairs placed over the biceps long head. Ultrasound imaging also used to visualize the long and short heads of the biceps in flexed and extended arm while the hand was in different postures. Depending on the task to be accomplished, activity was larger in one head or in the other. Being able to activate either head of the biceps, while not yet completely independently, suggests that the selective use of compartments could be a possible avenue for controlling upper limb myoelectric prostheses.

Les systèmes neuromusculaires et musculo-squelettique sont considérés comme un système de systèmes complexe. En effet, le mouvement du corps humain est contrôlé par le système nerveux central par l'activation des cellules musculaires squelettiques. L'activation du muscle produit deux phénomènes différents : mécanique et électrique. Ces deux activités possèdent des propriétés différentes, mais l'activité mécanique ne peut avoir lieu sans l'activité électrique et réciproquement. L'activité mécanique de la contraction du muscle squelettique est responsable du mouvement. Le mouvement étant primordial pour la vie humaine, il est crucial de comprendre son fonctionnement et sa génération qui pourront aider à détecter des déficiences dans les systèmes neuromusculaire et musculo-squelettique. Ce mouvement est décrit par les forces musculaires et les moments agissant sur une articulation particulière. En conséquence, les systèmes neuromusculaires et musculo-squelettique peuvent être évalués avec le diagnostic et le management des maladies neurologiques et orthopédiques à travers l'estimation de la force. Néanmoins, la force produite par un seul muscle ne peut être mesurée que par une technique très invasive. C'est pour cela, que l'estimation de cette force reste l'un des grands challenges de la biomécanique. De plus, comme dit précédemment, l'activation musculaire possède aussi une réponse électrique qui est corrélée à la réponse mécanique. Cette résultante électrique est appelée l'électromyogramme (EMG) et peut être mesurée d'une façon non invasive à l'aide d'électrodes de surface. L'EMG est la somme des trains de potentiel d'action d'unité motrice qui sont responsable de la contraction musculaire et de la génération du mouvement. Ce signal électrique peut être mesuré par des électrodes à la surface de la peau et est appelé I'EMG de surface {sEMG). Pour un muscle unique, en supposant que la relation entre l'amplitude du sEMG et la force est monotone, plusieurs études ont essayé d'estimer cette force en développant des modèles actionnés par ce signal. Toutefois, ces modèles contiennent plusieurs limites à cause des hypothèses irréalistes par rapport à l'activation neurale. Dans cette thèse, nous proposons un nouveau modèle de relation sEMG/force en intégrant ce qu'on appelle le sEMG haute définition (HD-sEMG), qui est une nouvelle technique d'enregistrement des signaux sEMG ayant démontré une meilleure estimation de la force en surmontant le problème de la position de l'électrode sur le muscle. Ce modèle de relation sEMG/force sera développé dans un contexte sans fatigue pour des contractions isométriques, isotoniques et anisotoniques du Biceps Brachii (BB) lors une flexion isométrique de l'articulation du coude à 90°. / The neuromuscular and musculoskeletal systems are complex System of Systems (SoS) that perfectly interact to provide motion. This interaction is illustrated by the muscular force, generated by muscle activation driven by the Central Nervous System (CNS) which pilots joint motion. The knowledge of the force level is highly important in biomechanical and clinical applications. However, the recording of the force produced by a unique muscle is impossible using noninvasive procedures. Therefore, it is necessary to develop a way to estimate it. The muscle activation also generates another electric phenomenon, measured at the skin using electrodes, namely the surface electromyogram (sEMG). ln the biomechanics literature, several models of the sEMG/force relationship are provided. They are principally used to command musculoskeletal models. However, these models suffer from several important limitations such lacks of physiological realism, personalization, and representability when using single sEMG channel input. ln this work, we propose to construct a model of the sEMG/force relationship for the Biceps Brachii (BB) based on the data analysis of a High Density sEMG (HD-sEMG) sensor network. For this purpose, we first have to prepare the data for the processing stage by denoising the sEMG signals and removing the parasite signals. Therefore, we propose a HD-sEMG denoising procedure based on Canonical Correlation Analysis (CCA) that removes two types of noise that degrade the sEMG signals and a source separation method that combines CCA and image segmentation in order to separate the electrical activities of the BB and the Brachialis (BR). Second, we have to extract the information from an 8 X 8 HD-sEMG electrode grid in order to form the input of the sEMG/force model Thusly, we investigated different parameters that describe muscle activation and can affect the relationship shape then we applied data fusion through an image segmentation algorithm. Finally, we proposed a new HDsEMG/force relationship, using simulated data from a realistic HD-sEMG generation model of the BB and a Twitch based model to estimate a specific force profile corresponding to a specific sEMG sensor network and muscle configuration. Then, we tested this new relationship in force estimation using both machine learning and analytical approaches. This study is motivated by the impossibility of obtaining the intrinsic force from one muscle in experimentation.

Ces dernières années, des travaux importants ont été observés dans le développement du contrôle prothétique afin d'aider les personnes amputées du membre supérieur à améliorer leur qualité de vie au quotidien. Certaines prothèses myoélectriques modernes des membres supérieurs disponibles dans le commerce ont de nombreux degrés de liberté et nécessitent de nombreux signaux de contrôle pour réaliser plusieurs tâches fréquemment utilisées dans la vie quotidienne. Pour obtenir plusieurs signaux de contrôle, de nombreux muscles sont requis mais pour les personnes ayant subi une amputation du membre supérieur, le nombre de muscles disponibles est plus ou moins réduit selon le niveau de l’amputation. Pour accroître le nombre de signaux de contrôle, nous nous sommes intéressés au biceps brachial, vu qu’anatomiquement il est formé de 2 chefs et que de la présence de compartiments a été observée sur sa face interne. Physiologiquement, il a été trouvé que les unités motrices du biceps sont activées à différents endroits du muscle lors de la production de diverses tâches fonctionnelles. De plus, il semblerait que le système nerveux central puisse se servir de la synergie musculaire pour arriver à facilement produire plusieurs mouvements. Dans un premier temps on a donc identifié que la synergie musculaire était présente chez le biceps de sujets normaux et on a montré que les caractéristiques de cette synergie permettaient d’identifier la posture statique de la main lorsque les signaux du biceps avaient été enregistrés. Dans un deuxième temps, on a réussi à démontrer qu’il était possible, dans un cube présenté sur écran, à contrôler la position d’une sphère en vue d’atteindre diverses cibles en utilisant la synergie musculaire du biceps. Les techniques de classification utilisées pourraient servir à faciliter le contrôle des prothèses myoélectriques. / In recent years, important work has been done in the development of prosthetic control to help upper limb amputees improve their quality of life on a daily basis. Some modern commercially available upper limb myoelectric prostheses have many degrees of freedom and require many control signals to perform several tasks commonly used in everyday life. To obtain several control signals, many muscles are required, but for people with upper limb amputation, the number of muscles available is more or less reduced, depending on the level of amputation. To increase the number of control signals, we were interested in the biceps brachii, since it is anatomically composed of 2 heads and the presence of compartments was observed on its internal face. Physiologically, it has been found that the motor units of the biceps are activated at different places of the muscle during production of various functional tasks. In addition, it appears that the central nervous system can use muscle synergy to easily produce multiple movements. In this research, muscle synergy was first identified to be present in the biceps of normal subjects, and it was shown that the characteristics of this synergy allowed the identification of static posture of the hand when the biceps signals had been recorded. In a second investigation, we demonstrated that it was possible in a virtual cube presented on a screen to control online the position of a sphere to reach various targets by using muscle synergy of the biceps. Classification techniques have been used to improve the classification of muscular synergy features, and these classification techniques can be integrated with control algorithm that produces dynamic movement of myoelectric prostheses to facilitate the training of prosthetic control.