Dissertations / Theses on the topic 'Signal EMG du muscle'
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1
Portero, Pierre. "Adaptation du muscle humain à la microgravité simulée : apport de l'analyse spectrale du signal EMG." Compiègne, 1993. http://www.theses.fr/1993COMP566S.
Abstract:
Les modifications des paramètres spectraux du signal électromyographique de surface (EMGS) des muscles Triceps Surae (T. S. ) et Tibialis Anterior (T. A. ), au cours d'une épreuve de fatigue isométrique, sont étudiées en relation avec une situation de microgravité simulée chez l'homme, c'est-à-dire lors d'une période de Bed Rest (B. R. ). La revue de la littérature a permis de montrer que : d'une part, lors d'une période de microgravité réelle ou simulée, les muscles à fonction antigravitaire (T. S) sont plus affectés que les muscles à fonction phasique (T. A. ) ; d'autre part, les paramètres spectraux EMGS évoluent différemment lors d'épreuves de fatigue et ceci en fonction de leurs caractéristiques métaboliques musculaires. L'étude a comporté deux phases principales : la première a consisté en la validation du protocole expérimental, la caractérisation des réponses des différents muscles en terme d'évolution des paramètres spectraux EMGS, et l'établissement d'une relation entre ces paramètres spectraux et certains paramètres du métabolisme musculaire exploré par spectroscopie RMN 31P ; la deuxième a été de caractériser l'évolution des paramètres spectraux EMGS en fonction du statut fonctionnel du T. S. Et du T. A. Lors d'une période de B. R. (4 semaines), avec et sans contre-mesures d'exercice musculaire. Les résultats montrent que : grâce à la méthode proposée (épreuve isométrique à 50% de la force maximale volontaire et analyse spectrale du signal EMGS), il est possible de différencier les évolutions des muscles en fonction de leur résistance à la fatigue grâce à l'établissement d'un débit de la fréquence moyenne (MPF) du spectre EMGS (% de diminution de la valeur initiale de la MPF par minute de temps de contraction). Ce débit constitue un index de fatigabilité d'un point de vue EMGS : il existe une relation entre le glissement spectral vers les basses fréquences de L'EMGS et la concentration musculaire en H2PO4 d'une part et H+ d'autre part ; il est possible de différencier ces évolutions par rapport à une situation de microgravité simulée, les différents chefs musculaires du T. S. (les gastrocnemii et le soleus) présentant une augmentation du débit de MPF contrairement au T. A. ; et enfin, lorsqu'un entraînement musculaire est non spécifique de la fonction des muscles étudiés, celui-ci n'est pas suffisant pour contrecarrer les effets du déconditionnement exprimés en terme EMGS. En conclusion, l'analyse spectrale du signal EMGS, lors d'épreuves de fatigue isométrique, apparaît comme étant un outil fiable pour discriminer les muscles par rapport à leur fonction antigravitaire (ou non) et en situation de microgravité simulée. L'aspect non invasif de cette méthode en fait une technique de choix pour le suivi de l'adaptation du muscle dans les domaines de la physiologie spatiale, sportive et de la médecine
2
Liu, Ming Ming. "Dynamic muscle force prediction from EMG signals using artificial neural networks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq20875.pdf.
3
Moss, Christa Wheeler. "INVESTIGATION OF BELOW INJURY MUSCLE SIGNALS AS A COMMAND SOURCE FOR A MOTOR NEUROPROSTHESIS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1315924472.
4
Joubert, Michelle. "A finite element model for the investigation of surface EMG signals during dynami contraction." Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-09042008-105943/.
5
Ayachi, Fouaz Sofiane. "Étude du recrutement des unités motrices par analyse du signal EMG de surface." Compiègne, 2011. http://www.theses.fr/2011COMP1998.
Abstract:
Le système nerveux central contrôle des mouvements par l’activation des unités de motrices (UM), les plus petites structures fonctionnelles du muscle. Les UM produisent une activité électrique qui peut être détectée par la technique de l’électromyographie de surface (EMGs). Le caractère stochastique du signal EMGs est dû principalement à la superposition des trains de potentiels d’action d’UM (TPAUM) (recrutement spatial), les TPAUM sont caractérisés par leurs instants de décharge (recrutement temporel), ainsi que par la forme des potentiels d’action (PA), qui dépend de certains facteurs méthodologiques et de facteurs intrinsèques au muscle. Le but de cette thèse sera d’étudier les possibilités et les limites d’utilisation de l’analyse de forme de la densité de probabilité des amplitudes (DP) du signal EMGs comme indicateur sur les stratégies de recrutement des UM et du contrôle moteur. Cette analyse semble pertinente puisque le signal EMGs est la somme de processus aléatoires ; les TPAUM. Des modifications sur ces variables devraient être perçues sur le signal composite. La contribution apportée par cette thèse se scinde en deux parties : la proposition d’un modèle complet de génération qui s’inspire de travaux récents issus de la littérature. Ce modèle prend en considération, pour la génération du signal EMGs, de nombreux paramètres physiologiques, anatomiques et nerveux, ainsi que la génération de la force. Cette prise en compte permet d’avoir un meilleur réalisme lors de la simulation. La deuxième partie concerne plusieurs études, en simulation et en expérimental, sur l’analyse des signaux EMGs monopolaires détectés sur le biceps brachial lors de contractions isométriques isotonique (force constante)/anisotonique (force graduée). L’objectif est d’extraire de l’information sur le patron de recrutement des UM à partir de ces signaux. Dans ce contexte, nous avons testé deux approches d’analyse de forme de la DP du signal EMGs qui sont la Statistique d’Ordre Supérieur (SOS), et un algorithme récent, le modèle de forme noyau (CSM : Core Shape Modeling). Les résultats indiquent une forte sensibilité des descripteurs proposés pour la séparation des classes de signaux (force, niveau de synchronisation de décharge), à l’effet filtrant du tissu adipeux et de la composante non propagée. L’efficacité de la classification dépend d’autre part de l’anatomie et du nombre d’UM composant le muscle. Pour les facteurs neuronaux, les deux stratégies de recrutement testées donnent les mêmes tendances avec plus de réalisme physiologique pour l’une d’entre elles. De plus, l’analyse de forme (par SOS), dans certains cas, nous donne des informations sur l’anatomie du muscle considéré, en termes de position de l’UM par rapport à l’électrode. En termes de performance de classification, l’algorithme CSM, donne un résultat relativement meilleur que l’approche SOS, que ce soit en simulation ou en expérimentation. Pour résumer, ce travail de thèse s’inscrit comme une démarche exploratoire du potentiel de l’analyse de forme de la DP du signal EMGs dans l’extraction d’information sur les modalités d’activation musculaire. De nombreux efforts restent à fournir en accord avec les perspectives proposéesThe central nervous system control the movement through the activation of the motors units (MUs), the smallest muscle functional structure. The MU produce electrical activity that can be detected by the technique of surface electromyography (sEMG). The stochastic nature of EMGs signal is mainly due to the superposition of trains of MU action potentials ( MUAPT) (spatial recruitment), the MUAPT are characterized by their discharge frequency (temporal recruitment) and the shape of the action potential (PA), which depends on some factors methodological and intrinsic to the muscle. The aim of this thesis is to study the possibilities and limitations of using the shape analysis of the EMGs signal’s probability density function (DP) as an indicator on MU recruitment strategies and motor control. This analysis seems relevant since the EMGs signal is the sum of random processes, the MUAPT. The contribution of this thesis is divided into two parts : the proposal of a complete model generation inspired by recent work from the literature. This model takes into consideration, for the EMGs signal generation, many physiological, anatomical and nervous parameters, as well as the force generation. Such consideration allows for greater realism in the simulation. The second part concerns several studies, simulation and experimental analysis of EMGs monopolar signals detected on the biceps brachii during isometric contractions isotonic (constant force) / anisotonique (graduated force). The aim is to extract information on the pattern of MU recruitment from these signals. In this context, we tested two approaches based on the shape analysis of the EMGs signal’s DP which are the Higher Order Statistics (HOS), and a recent algorithm, the Core Shape Modeling (CSM). The results indicate a high sensitivity of the proposed descriptors for separating classes of signals (force, sync level of the discharge), the filtering effect of adipose tissue and non propagating component. The efficiency of the classification depends the other hand of the anatomy and the number of MU which composed the muscle. For neuronal factors, both recruitment strategies tested give similar trends with one of them is physiologically more realistic. In addition, analysis of shape (SOS), in some cases, gives us information about muscle anatomy of the concerned muscle, in terms of MU position relative to the electrode. Concerning performance of classification, the algorithm CSM gives a result relatively better than SOS approach, either in simulation or experimentation. To summarize, this thesis is listed as an exploratory process of the shape analysis potential of the EMGs signal’s DP in order to extract the information on the muscular activation’s modalities. A lot of efforts are still required in accordance with the perspectives offered
6
KHALIL, ULLAH XXX. "Extraction of Muscle Anatomical and Physiological Information from Multi-Channel Surface EMG Signals: Applications in Obstetrics." Doctoral thesis, Politecnico di Torino, 2016. http://hdl.handle.net/11583/2642318.
Abstract:
Motor Unit (MU) innervation zones (IZs) localization is an important step in several clinical and non-clinical applications including 1) Acquisition of sEMG signal for accurate estimation of its amplitude and other parameters by avoiding placing the electrodes on IZs, 2) Accurate estimation of the EMG-Force relationship, 3) Effective injection of Botulinum Toxin in Post-stroke Spasticity near the IZs, and 4) Guiding the obstetricians to perform episiotomy during child delivery by avoiding cutting near the IZs of External Anal Sphincter (EAS) muscle. The minimal invasive way to identify the location of the IZs generally for any muscle and specifically for EAS muscle is to use multi-channel EMG signals. MU IZs can be detected from the multi-channel sEMG signals, for a fusiform muscle if the signal is acquired with an array of electrodes placed parallel to the muscle fibers, using digital signal and image processing algorithms. As most of the signal processing algorithms work on an adequate quality of the signal, thus before detecting the innervation zone it is made sure that the signal is of good quality. For this purpose, a method based on statistical thresholding of various parameters is proposed to detect the bad channels in the sEMG signals. If the number of the bad consecutive channels are more than 2 then it is suggested to acquire the signal again, otherwise each bad channel is approximated by the interpolation of its neighbor channels. As some background noise is always acquired with the EMG signal so further image enhancement techniques are used to enhance the MUAP propagation region in the spatio-temporal images and suppress the background noise. The MUAP pattern is then detected in the spatio-temporal sEMG images using multi-scale Hessian based filtering and the corresponding MU IZs are identified as the starting point of propagation of the MUAP. A software is also developed which can be used to visualize the signals acquired from EAS, detect and display the IZs and more importantly compute and display the histogram of the IZs and generate reports which will help the obstetrician while performing episiotomy during child delivery to avoid cutting vulnerable regions that may lead to fecal incontinence at later age.
7
Rahman, Md Arifur. "A comparative study to explore the advantages of passive exoskeletons by monitoring the muscle activity of workers." Thesis, Högskolan i Gävle, Avdelningen för elektroteknik, matematik och naturvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-35150.
Abstract:
Manufacturing and construction workers undertake physically strenuous activities increasing the risk of health problems, disability, and sick leave, leading to lower job attractiveness and job candidate scarcity. In the EU, up to 44 million workers are affected by workplace-related musculoskeletal disorders (MSDs), representing a total annual cost of more than €240 billion. Exoskeleton use could alleviate muscle peak loads and reduce the risks of injury of workers. This work is related to the INTERREG's project "EXSCALLERATE" which aimed to accelerate the adoption of exoskeletons among SMEs. This research presents a comparative study of using exoskeletons by workers while performing different tasks related to their job. The tests evaluate the advantages of using exoskeletons in reducing human muscle activity, thereby, reducing the fatigue and tiredness. The study uses two commercially available exoskeletons, (1) upper body exoskeleton known as Eksovest and (2) lower body exoskeleton known as LegX. For upper body, the study performed drilling tasks at shoulder height and roof drilling positions, whereas, for the lower body, virtual chair position and squatting positions are tested which involved frequent bending of knees. Besides, the experiments based on accuracies of the data collection techniques and compare three volunteer’s body muscle data acquired by EMG sensor. From these comparisons, it is found that the muscle activity can be reduced up to 60% by using these exoskeletons, hence, increasing the work life of the workforce. The results of this study will help create awareness among SMEs towards the adoption of exoskeletons.
8
Rojas, Martínez Mónica. "Analysis of forearm muscles activity by means of new protocols of multichannel EMG signal recording and processing." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/124507.
Abstract:
Los movimientos voluntarios del cuerpo son controlados por el sistema nervioso central y periférico a través de la contracción de los músculos esqueléticos. La contracción se inicia al liberarse un neurotransmisor sobre la unión neuromuscular, iniciando la propagación de un biopotencial sobre la membrana de las fibras musculares que se desplaza hacia los tendones: el Potencial de Acción de la Unidad Motora (MUAP). La señal electromiográfica de superficie registra la activación continua de dichos potenciales sobre la superficie de la piel y constituye una valiosa herramienta para la investigación, diagnóstico y seguimiento clínico de trastornos musculares, así como para la identificación de la intención movimiento tanto en términos de dirección como de potencia.
En el estudio de las enfermedades del sistema neuromuscular es necesario analizar el nivel de actividad, la capacidad de producción de fuerza, la activación muscular conjunta y la predisposición a la fatiga muscular, todos ellos asociados con factores fisiológicos que determinan la resultante contracción mioeléctrica. Además, el uso de matrices de electrodos facilita la investigación de las propiedades periféricas de las unidades motoras activas, las características anatómicas del músculo y los cambios espaciales en su activación,
ocasionados por el tipo de tarea motora o la potencia de la misma.
El objetivo principal de esta tesis es el diseño e implementación de protocolos experimentales y algoritmos de procesado para extraer información fiable de señales sEMG multicanal en 1 y 2 dimensiones del espacio. Dicha información ha sido interpretada y relacionada con dos patologías específicas de la extremidad superior: Epicondilitis Lateral y Lesión de Esfuerzo Repetitivo. También fue utilizada para identificar la dirección de movimiento y la fuerza asociada a la contracción muscular, cuyos patrones podrían ser de utilidad en aplicaciones donde la señal electromiográfica se utilice para controlar interfaces hombre-máquina como es el caso de terapia física basada en robots, entornos virtuales de rehabilitación o realimentación de la actividad muscular.
En resumen, las aportaciones más relevantes de esta tesis son:
* La definición de protocolos experimentales orientados al registro de señales sEMG en una región óptima del músculo.
* Definición de índices asociados a la co-activación de diferentes músculos
* Identificación de señales artefactuadas en registros multicanal
* Selección de los canales mas relevantes para el análisis
Extracción de un conjunto de características que permita una alta exactitud en la identificación de tareas motoras
Los protocolos experimentales y los índices propuestos permitieron establecer que diversos desequilibrios entre músculos extrínsecos del antebrazo podrían desempeñar un papel clave en la fisiopatología de la epicondilitis lateral. Los resultados fueron consistentes en diferentes ejercicios y pueden definir un marco de evaluación para el seguimiento y evaluación de pacientes en programas de rehabilitación motora.
Por otra parte, se encontró que las características asociadas con la distribución espacial de los MUAPs mejoran la exactitud en la identificación de la intención de movimiento. Lo que es más, las características extraídas de registros sEMG de alta densidad son más
robustas que las extraídas de señales bipolares simples, no sólo por la redundancia de contacto implicada en HD-EMG, sino también porque permite monitorizar las regiones del músculo donde la amplitud de la señal es máxima y que varían con el tipo de ejercicio, permitiendo así una mejor estimación de la activación muscular mediante el análisis de los canales mas relevantes.Voluntary movements are achieved by the contraction of skeletal muscles controlled by the Central and Peripheral Nervous system. The contraction is initiated by the release of a neurotransmitter that promotes a reaction in the walls of the muscular fiber, producing a biopotential known as Motor Unit Action Potential (MUAP) that travels from the neuromuscular junction to the tendons. The surface electromyographic signal records the continuous activation of such potentials over the surface of the skin and constitutes a valuable tool for the diagnosis, monitoring and clinical research of muscular disorders as well as to infer motion intention not only regarding the direction of the movement but also its power. In the study of diseases of the neuromuscular system it is necessary to analyze the level of activity, the capacity of production of strength, the load-sharing between muscles and the probably predisposition to muscular fatigue, all of them associated with physiological factors determining the resultant muscular contraction. Moreover, the use of electrode arrays facilitate the investigation of the peripheral properties of the active Motor Units, the anatomical characteristics of the muscle and the spatial changes induced in their activation of as product of type of movement or power of the contraction.The main objective of this thesis was the design and implementation of experimental protocols, and algorithms to extract information from multichannel sEMG signals in 1 and 2 dimensions of the space. Such information was interpreted and related to pathological events associated to two upper-limb conditions: Lateral Epicondylitis and Repetitive Strain Injury. It was also used to identify the direction of movement and contraction strength which could be useful in applications concerning the use of biofeedback from EMG like in robotic- aided therapies and computer-based rehabilitation training.In summary, the most relevant contributions are:§The definition of experimental protocols intended to find optimal regions for the recording of sEMG signals. §The definition of indices associated to the co- activation of different muscles. §The detection of low-quality signals in multichannel sEMG recordings.§ The selection of the most relevant EMG channels for the analysis§The extraction of a set of features that led to high classification accuracy in the identification of tasks.The experimental protocols and the proposed indices allowed establishing that imbalances between extrinsic muscles of the forearm could play a key role in the pathophysiology of lateral epicondylalgia. Results were consistent in different types of motor task and may define an assessment framework for the monitoring and evaluation of patients during rehabilitation programs.On the other hand, it was found that features associated with the spatial distribution of the MUAPs improve the accuracy of the identification of motion intention. What is more, features extracted from high density EMG recordings are more robust not only because it implies contact redundancy but also because it allows the tracking of (task changing) skin surface areas where EMG amplitude is maximal and a better estimation of muscle activity by the proper selection of the most significant channels.
9
Cao, Hua. "Modélisation et évaluation expérimentale de la relation entre le signal EMG de surface et la force musculaire." Compiègne, 2010. http://www.theses.fr/2010COMP1856.
Abstract:
L’estimation de la force générée par un muscle est importante dans les études biomécaniques et pour les applications cliniques. Puisque cette force ne peut pas être mesurée directement, le signal électromyographique de surface (SEMG), reflétant le niveau d’activation musculaire, est utilisé pour quantifier la force développée. Cependant, tous les facteurs, contrôlant une contraction isométrique, n’influencent pas la force et le SEMG simultanément. Le but de ce travail de thèse est donc de développer un modèle de simulation conjointe du SEMG et de la force, afin d’étudier la relation EMG-force. Dans ce but, nous avons d’abord développé une nouvelle méthode de simulation de la force musculaire à partir d’un modèle d’EMG existant. Le modèle complet a été testé pour le choix de la stratégie de recrutement et l’influence de la durée de la consigne. Puis, nous avons utilisé une méthode de Monte Carlo pour étudier la sensibilité du modèle aux différents paramètres physiologiques d’entrée. Deux critères existants (relations EMG-force et force-variabilité de force) ainsi qu’un nouveau critère (erreur entre la consigne de force et la force générée), ont été utilisés pour optimiser les paramètres avec une consigne de force constante. Ce nouveau critère a ensuite été utilisé avec une consigne de force variable (sinusoïdale ou triangulaire), afin d’obtenir les plages optimales des paramètres. Enfin, pour évaluer notre modèle, nous avons réalisés des expérimentations et une simulation pour le biceps. Les résultats montrent que notre modèle EMG-force est capable de simuler qualitativement les comportements réels du biceps pour les contractions isotoniques et anisotoniquesThe estimation of the force generated by a muscle is important in biomechanical studies and clinical applications. As this force cannot be measured directly, the surface electromyography signal (SEMG), reflecting the level of muscle activation, is used to quantify the force developed. However, all the factors controlling an isometric contraction do not influence the force and the SEMG simultaneously. The aim of this study is to develop a simulation model of SEMG and force in order to study the EMG-force relationship. For this purpose, we first developed a new method to simulate the muscle force from an existing EMG model. We tested the complete model with two recruitment strategies and studied the influence of target force duration. Then we used a Monte Carlo method to study the sensitivity of the model to various input physiological parameters. Two existing criteria (EMG-force and force-force variability relationships) and a new criterion (error between the target force and the generated force) were used to optimize the parameters in constant target force contractions. This new criterion was then used in variable target force contractions (sinusoidal or triangular target) in order to obtain the optimum parameter ranges. Finally, to evaluate our model, we performed experiments and simulations for the biceps. The results have shown that our EMG-force model can qualitatively simulate the behaviour of the biceps for isotonic and anisotonic contractions
10
Grönlund, Christer. "Spatio-temporal processing of surface electromyographic signals : information on neuromuscular function and control." Doctoral thesis, Umeå universitet, Institutionen för strålningsvetenskaper, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-958.
Abstract:
During muscle contraction, electrical signals are generated by the muscle cells. The analysis of those signals is called electromyography (EMG). The EMG signal is mainly determined by physiological factors including so called central factors (central nervous system origin) and peripheral factors (muscle tissue origin). In addition, during the acquisition of EMG signals, technical factors are introduced (measurement equipment origin). The aim of this dissertation was to develop and evaluate methods to estimate physiological properties of the muscles using multichannel surface EMG (MCsEMG) signals. In order to obtain accurate physiological estimates, a method for automatic signal quality estimation was developed. The method’s performance was evaluated using visually classified signals, and the results demonstrated high classification accuracy. A method for estimation of the muscle fibre conduction velocity (MFCV) and the muscle fibre orientation (MFO) was developed. The method was evaluated with synthetic signals and demonstrated high estimation precision at low contraction levels. In order to discriminate between the estimates of MFCV and MFO belonging to single or populations of motor units (MUs), density regions of so called spatial distributions were examined. This method was applied in a study of the trapezius muscle and demonstrated spatial separation of MFCV (as well as MFO) even at high contraction levels. In addition, a method for quantification of MU synchronisation was developed. The performance on synthetic sEMG signals showed high sensitivity on MU synchronisation and robustness to changes in MFCV. The method was applied in a study of the biceps brachii muscle and the relation to force tremor during fatigue. The results showed that MU synchronisation accounted for about 40 % of the force tremor. In conclusion, new sEMG methods were developed to study muscle function and motor control in terms of muscle architecture, muscle fibre characteristics, and processes within the central nervous system.
11
Potes, Cristhian Mauricio. "Assessment of human muscle fatigue from surface EMG signals recorded during isometric voluntary contractions by using a cosine modulated filter bank." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2008. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Emrani, Mahdieh Sadat. "Relationships Between Motor Unit Anatomical Characteristics and Motor Unit Potential Statistics in Healthy Muscles." Thesis, University of Waterloo, 2005. http://hdl.handle.net/10012/897.
Abstract:
The main goal of this thesis was to discover the relationships between MU characteristics and MUP features. To reach this goal, several features explaining the anatomical structure of the muscle were introduced. Additionally, features representing specific properties of the EMG signal detected from that muscle, were defined. Since information regarding the underlying anatomy was not available from real data, a physiologically based muscle model was used to extract the required features. This muscle model stands out from others, by providing similar acquisition schemes as the ones utilized by physicians in real clinical settings and by modelling the interactions among different volume conductor factors and the collection of MUs in the muscle in a realistic way. Having the features ready, several relationship discovery techniques were used, to reveal relationships between MU features and MUP features. To interpret the results obtained from the correlation analysis and pattern discovery techniques properly, several algorithms and new statistics were defined. The results obtained from correlation analysis and pattern discovery technique were similar to each other, and suggested that to maximize the inter-relationships between MUP features and MU features, MUPs could be filtered based on their slope values, specifically MUPs with slopes lower than 0. 6 v/s could be excluded. Additionally PDT results showed that high slope MUPs were not as informative about the underlying MU and could be excluded to maximize the relationships between MUP features and MU characteristics. Certain MUP features were determined to be highly related to certain MU characteristics. MUP area and duration were shown to be the best representative feature for the MU size and average fiber density, respectively. For the distribution of fiber diameter in the MU, duration and number of turns were determined to reflect mean fiber diameter and stdv of fiber diameter the best, correspondingly.
13
Sahki, Nassim. "Méthodologie data-driven de détection séquentielle de ruptures pour des signaux physiologiques." Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0185.
Abstract:
Cette thèse traite de la problématique de la détection de rupture dans le cadre séquentiel où le signal est supposé être observé en temps réel et le phénomène passe de son état de départ "normal" à un état post-changement "anormal". Le défi de la détection séquentielle est de minimiser le délai de détection, soumis à une limite tolérable de fausse alarme. L'idée est de tester séquentiellement l'existence d'une rupture par l'écriture récursive de la statistique de détection en fonction du score, qui remplace le Log-Likelihood Ratio lorsque la distribution des données est inconnue. La procédure de détection repose ainsi sur une statistique récursive, un seuil de détection et une règle d'arrêt. Dans un premier travail, nous considérons la statistique score-CUSUM et proposons d'évaluer la performance de détection de certains seuils de détection. Deux seuils sont issus de la littérature, et trois nouveaux seuils sont construits par une méthode basée sur la simulation: le premier est constant, le second instantané et le troisième est une version dynamique "data-driven" du précédent. Nous définissons rigoureusement chacun des seuils en mettant en évidence les différentes notions du risque de fausse alarme contrôlé suivant le seuil. Par ailleurs, nous proposons une nouvelle règle d'arrêt corrigée pour réduire le taux de fausse alarme. Nous effectuons ensuite une étude de simulation pour comparer les différents seuils et évaluer la règle d'arrêt corrigée. Nous constatons que le seuil empirique conditionnel est le meilleur pour minimiser le délai de détection tout en maintenant le risque toléré de fausse alarme. Cependant, sur des données réelles, nous recommandons d'utiliser le seuil data-driven car c'est le plus simple à construire et à utiliser pour une implémentation pratique. Dans la seconde partie, nous appliquons notre méthodologie de détection data-driven sur des signaux physiologiques, à savoir des signaux temporels enregistrés au niveau du faisceau supérieur du trapèze de 30 sujets effectuant différentes activités bureautiques. La méthodologie est sujet-activité dépendante; elle inclut l'estimation on-line des paramètres du signal et la construction du seuil data-driven sur le début du signal de chaque activité de chaque sujet. L'objectif était d'identifier des changements de régimes au cours d'une activité afin d'évaluer le niveau de sollicitation du muscle et la variabilité du signal EMG, qui sont liés à la fatigue musculaire. Les résultats obtenus ont confirmé l'aisance de notre méthodologie et la performance et praticité du seuil data-driven proposé. Par la suite, les résultats ont permis la caractérisation de chaque type d'activité en utilisant des modèles mixtesThis thesis deals the problem of change-point detection in the sequential framework where the signal is assumed to be observed in real time and the phenomenon changes from its "normal" starting state to an "abnormal" post-change state. The challenge of sequential detection is to minimize the detection delay, subject to a tolerable false alarm limit. The idea is to sequentially test for the existence of a change-point by recursively writing the detection statistic as a function of the score, which replaces the Log-Likelihood Ratio when the data distribution is unknown. The detection procedure is thus based on a recursive statistic, a detection threshold and a stopping rule. In a first work, we consider the score-CUSUM statistic and propose to evaluate the detection performance of some detection thresholds. Two thresholds come from the literature, and three new thresholds are constructed by a method based on simulation: the first is constant, the second instantaneous and the third is a dynamic "data-driven" version of the previous one. We rigorously define each of the thresholds by highlighting the different notions of the controlled false alarm risk according to the threshold. Moreover, we propose a new corrected stopping rule to reduce the false alarm rate. We then perform a simulation study to compare the different thresholds and evaluate the corrected stopping rule. We find that the conditional empirical threshold is the best to minimize the detection delay while maintaining the tolerated risk of false alarms. However, on real data, we recommend using the data-driven threshold as it is the easiest to build and use for practical implementation. In the second part, we apply our data-driven detection methodology to physiological signals, namely temporal signals recorded at the level of the upper trapezium beam of 30 subjects performing different office activities. The methodology is subject-activity dependent; it includes the on-line estimation of the signal parameters and the construction of the data-driven threshold on the start of the signal of each activity of each subject. The objective was to identify regime changes during an activity in order to assess the level of muscle solicitation and EMG signal variability, which are associated with muscle fatigue. The results obtained confirmed the ease of our methodology and the performance and practicality of the proposed data-driven threshold. Subsequently, the results allowed the characterization of each type of activity using mixed models
14
Kamei, Ken, and ken kamei@student rmit edu au. "The reliability and validity of surface electromyography to study the functional status of the lumbar paraspinal muscles." RMIT University. Health Science, 2010. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20100210.145414.
Abstract:
The aim of this thesis is to determine whether surface electromyography (EMG) can be used as a diagnostic tool in chiropractic practice to identify the functional status of the lumbar paraspinal muscles. There were two main studies to achieve this aim. The reliability and validity of the surface EMG signal to measure the activity of paraspinal muscles during maintenance of simple static postures was evaluated. During maintenance of static postures, the raw surface EMG signal was often contaminated by an electrocardiographic (ECG) signal. Although the ECG artefact was successfully removed using two different ECG removal techniques (manual and semi-automatic), the reliability of the surface EMG signal was not significantly improved (ICC less than 0.75) for both non-normalised and normalised data. Therefore the static postures that were used in this thesis did not provide a protocol that can be used to measure the functional status of the lumbar paraspinal muscles in clinical practice. However, when muscle contraction was at a moderate level, the reliability of EMG signal became better. Walking was considered to be a possible protocol to record a reliable surface EMG signal from paraspinal muscles. Three components of the surface EMG signal were used to characterise the pattern of muscle activity during steady state walking. The narrow window technique was used to characterise the peak activation point of the activity envelope in order to capture a stationary signal from which to calculate amplitude and frequency measures. Walking is a cyclic activity. The back muscles contract rhythmically during a single gait cycle. It is possible to identify the start and end points of the activity envelope associated with the rhythmic contraction of the muscles and define the timing of the muscle activation cycle relative to heel strike. The metronome was found to be useful to control the pace of natural walking in this study. The surface EMG signal of the first recording minute (1 ~ 2 minute) was not associated with a signal that was stable in terms of the parameters that were used in this study. It wa s found that the last recording minute (9 ~ 10 minute) can be used. This suggests that it may be necessary for subjects to walk for a defined period lasting some minutes before the commencement of recording of the surface EMG. Surface EMG may be used as a tool to measure activation patterns of the low back muscles during muscle contraction associated with the support of various static postures or during the execution of dynamic movements such as walking in the real world. The static postures used in this thesis to record the surface EMG signal from the lumbar paraspinal muscles were found not to provide the basis for a reliable and valid tool. However, a walking exercise might be an alternative activity which can be used easily in clinical practice. The components of the surface EMG signal that may be used in future studies might include measures of the amplitude, frequency and timing of the surface EMG signal.
15
North, Graham M. "Signal characteristics of surface EMG." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55624.
16
Goncalves, Carlos Alberto. "Techniques d'évaluation de la vitesse de conduction des potentiels d'action musculaires : application à l'interprétation des remaniements spectraux de l'électromyogramme." Compiègne, 1985. http://www.theses.fr/1985COMPI195.
17
Plassman, Brenda L. 1957. "INSPIRATORY MUSCLE RESPONSES TO OCCLUSION (EMG)." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/291244.
18
Bida, Oljeta. "Influence of electromyogram (EMG) amplitude processing in EMG-torque estimation." Link to electronic thesis, 2005. http://www.wpi.edu/Pubs/ETD/Available/etd--01295-140510/.
Abstract:
Thesis (M.S.)--Worcester Polytechnic Institute.Keywords: system identification; EMG; optimal sampling rate; linear torque model; EMG-torque model; EMG amplitude; torque. Includes bibliographical references (p. 77-86).
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Szöllösi, Tomáš. "Měření EMG a posouzení vlivu zátěže." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-374762.
Abstract:
The task of this thesis was focused on influence of physical load on electrical activity of muscle. There are basic principals and terms from the problematic of measuring electric activity of muscle. Author suggested measuring protocol, got data from group of people, made an application and used this application to analyse measured signals. At the end of this work it was suggested statistical processing and evaluation of results.
20
Young, Richard N. (Richard Norman). "The effect of muscle contractility on surface EMG /." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60423.
Abstract:
This study was designed as an investigation of the role of changes in muscle force and changes in muscle length on the EMG for the Tibialis Anterior (TA).Using surface electrodes we examined the EMG for 4 contraction levels at 5 ankle positions over 60$ sp circ$ of ankle rotation. The change in median frequency with muscle length identified a significant shift in the power spectrum to lower frequencies with increasing muscle length.
To further investigate our results we performed three other experiments: First, using X-rays to identify the relative change in distance between two intramuscular wire electrodes we found the change in TA muscle length for this study to be 15% over the 60$ sp circ$ of ankle rotation. Second, to test for synergist contamination we used fine wire electrodes in the Extensor Digitorum Longus and the Peroneus. We found no evidence to support significant contamination. Third, we examined the role of smaller electrodes with a smaller interelectrode distance on our findings. The EMG showed drastic changes with even a slight shift in electrode position most likely due to the large number of innervation zones.
Therefore, the results indicate a shift in the power spectrum with a change in muscle length. In addition, surface EMG results are heavily dependent on the innervation zones and on the electrode geometry, all of which are important considerations in developing the EMG as an accurate diagnostic tool.
21
Cutts, Alison. "Surface EMG as an indicator of muscle force." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328893.
22
E, N. Shaban, and V. Abousetta S. "Online EMG signal analysis for Parkinson’s tremor determination." Thesis, Boston, USA, 2020. http://openarchive.nure.ua/handle/document/11838.
Abstract:
In this paper, we introduced a general development of software for quantifying the severity of the Parkinson's tremor. The extracted features from the surface EMG of the wrist and hand muscles were the input of the designed model of the application. Using the application that can record reliably the EMG signals and quantify the levels of tremor may contribute to the early diagnosis of the disorder online.
23
Shaban, N. E., and V. S. Abousetta. "Online EMG signal analysis for Parkinson’s tremor determination." Thesis, Boston, USA, 2020. http://openarchive.nure.ua/handle/document/13654.
Abstract:
In this paper, we introduced a general development of software for quantifying the severity of the Parkinson's tremor. The extracted features from the surface EMG of the wrist and hand muscles were the input of the designed model of the application. Using the application that can record reliably the EMG signals and quantify the levels of tremor may contribute to the early diagnosis of the disorder online.
24
Keating, Jennifer. "Relating forearm muscle electrical activity to finger forces." Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-theses/580.
Abstract:
The electromyogram (EMG) signal is desired to be used as a control signal for applications such as multifunction prostheses, wheelchair navigation, gait generation, grasping control, virtual keyboards, and gesture-based interfaces [25]. Several research studies have attempted to relate the electromyogram (EMG) activity of the forearm muscles to the mechanical activity of the wrist, hand and/or fingers [41], [42], [43]. A primary interest is for EMG control of powered upper-limb prostheses and rehabilitation orthotics. Existing commercial EMG-controlled devices are limited to rudimentary control capabilities of either discrete states (e.g. hand close/open), or one degree of freedom proportional control [4], [36]. Classification schemes for discriminating between hand/wrist functions and individual finger movements have demonstrated accuracy up to 95% [38], [39], [29]. These methods may provide for increased amputee function, though continuous control of movement is not generally achieved. This thesis considered proportional control via EMG-based estimation of finger forces with the goal of identifying whether multiple degrees of freedom of proportional control information are available from the surface EMG of the forearm. Electromyogram (EMG) activity from the extensor and flexor muscles of the forearm was sensed with bipolar surface electrodes and related to the force produced at the four fingertips during constant-posture, slowly force-varying contractions from 20 healthy subjects. The contractions ranged between 30% maximum voluntary contractions (MVC) extension and 30% MVC flexion. EMG amplitude sampling rate, least squares regularization, linear vs. nonlinear models and number of electrodes used in the system identification were studied. Results are supportive that multiple degrees of freedom of proportional control information are available from the surface EMG of the forearm, at least in healthy subjects. An EMG amplitude sampling frequency of 4.096 Hz was found to produce models which allowed for good EMG amplitude estimates. Least squares regularization with a pseudo-inverse tolerance of 0.055 resulted in significant improvement in modeling results, with an average error of 4.69% MVC-6.59% MVC (maximum voluntary contraction). Increasing polynomial order did not significantly improve modeling results. Results from smaller electrode arrays remained fairly good with as few as six electrodes, with the average %MVC error ranging from 5.13%-7.01% across the four fingers. This study also identified challenges in the current experimental study design and subsequent system identification when EMG-force modeling is performed with four fingers simultaneously. Methods to compensate for these issues have been proposed in this thesis.
25
Liu, Lukai. "A Study of Myoelectric Signal Processing." Digital WPI, 2016. https://digitalcommons.wpi.edu/etd-dissertations/34.
Abstract:
This dissertation of various aspects of electromyogram (EMG: muscle electrical activity) signal processing is comprised of two projects in which I was the lead investigator and two team projects in which I participated. The first investigator-led project was a study of reconstructing continuous EMG discharge rates from neural impulses. Related methods for calculating neural firing rates in other contexts were adapted and applied to the intramuscular motor unit action potential train firing rate. Statistical results based on simulation and clinical data suggest that performances of spline-based methods are superior to conventional filter-based methods in the absence of decomposition error, but they unacceptably degrade in the presence of even the smallest decomposition errors present in real EMG data, which is typically around 3-5%. Optimal parameters for each method are found, and with normal decomposition error rates, ranks of these methods with their optimal parameters are given. Overall, Hanning filtering and Berger methods exhibit consistent and significant advantages over other methods. In the second investigator-led project, the technique of signal whitening was applied prior to motion classification of upper limb surface EMG signals previously collected from the forearm muscles of intact and amputee subjects. The motions classified consisted of 11 hand and wrist actions pertaining to prosthesis control. Theoretical models and experimental data showed that whitening increased EMG signal bandwidth by 65-75% and the coefficients of variation of temporal features computed from the EMG were reduced. As a result, a consistent classification accuracy improvement of 3-5% was observed for all subjects at small analysis durations (< 100 ms). In the first team-based project, advanced modeling methods of the constant posture EMG-torque relationship about the elbow were studied: whitened and multi-channel EMG signals, training set duration, regularized model parameter estimation and nonlinear models. Combined, these methods reduced error to less than a quarter of standard techniques. In the second team-based project, a study related biceps-triceps surface EMG to elbow torque at seven joint angles during constant-posture contractions. Models accounting for co-contraction estimated that individual flexion muscle torques were much higher than models that did not account for co-contraction.
26
Konté, Cheick-Suhaibou. "Modélisation de l'atténuation du signal EMG diaphragmatique de surface." Grenoble, 2010. http://www.theses.fr/2010GRENS009.
Abstract:
Le recueil du signal EMG diaphragmatique par voie de surface est une mesure délicate. L'atténuation induite par les différents tissus se situant sur le trajet diaphragme-électrode et la faiblesse de l'amplitude des potentiels générés sont à l'origine d'un rapport signal sur bruit qui rend l'analyse de ce signal particulièrement difficile. Dans ce travail de thèse, nous proposons d'évaluer cette atténuation à deux niveaux d'échelles : Une première échelle appelée " grand volume " consiste à considérer la cage thoracique comme homogène et constituée de tissu pulmonaire et d'évaluer l'atténuation du signal diaphragmatique en fonction de la distance fibre électrode et de la conductivité du tissu pulmonaire. La volonté de confronter les résultats de modélisation avec des mesures expérimentales, nous a conduit à considérer le cas spécifique de la mesure œsophagienne couplée à une stimulation phrénique. Nous avons utilisé un plan d'expériences pour analyser les différents paramètres d'influence. Cette première approche était basée sur un modèle analytique. Une deuxième échelle, consiste à prendre compte l'effet d'inhomogénéités sur le trajet fibre-électrode. Cette étape, conduite à titre prospectif, est ici centrée sur l'analyse de l'influence des cotes sur l'atténuation du signal. A cette échelle, la confrontation avec la mesure devient plus délicate et nous proposons une étude basée sur la seule modélisation. Cette dernière est conduite ici à l'aide des éléments finisThe detection of diaphragmatic EMG signal by surface is a hard measure. The attenuation induced by the different tissues lying on the way diaphragm electrode and low amplitude potentials are generated to cause a signal to noise ratio which makes the analysis of the signal difficult. In this thesis, we propose to evaluate the levels of attenuation at two steps: A first level called "large volume" of considering the thorax as homogeneous and consists of lung tissue and to assess the diaphragmatic attenuation as a function of distance fiber electrode and the conductivity of the lung tissue. The desire to compare modeling results with experimental measurements, led us to consider the specific case of measuring esophageal coupled with phrenic nerve stimulation. We used an experimental design to analyze the different parameters of influence. This first approach was based on an analytical model. A second level is to take into account the effect of inhomogeneities on the path fiber electrode. This stage, conducted prospectively, is here focused on the analysis of the influence of ratings on the signal attenuation. At this scale, the confrontation with the measurement becomes more difficult and we propose a study based solely on modeling. The latter is conducted by using finite elements
27
Magbonde, Abilé. "Séparation de signaux électromyographiques de surface à haute densité pour la réduction de la diaphonie." Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALT008.
Abstract:
L’utilisation du signal électrique musculaire de surface (EMG) dans une perspective biomécanique, thérapeutique ou pour la commande nécessite une forte sélectivité spatiale des signaux. Pour des muscles contigus, cette contrainte est rarement observée rendant l’utilisation du signal EMG difficile. La diaphonie, ou contamination croisée des signaux, inhérentes aux enregistrements doit alors être supprimée.Cette thèse a pour but de proposer des méthodes pour séparer la diaphonie lorsque les muscles extenseurs de l'index et du petit doigt sont en contraction simultanée. Notre travail consiste alors à extraire l’activité musculaire liée à chaque muscle dans un contexte de séparation de sources. Pour cela, une première partie du travail a consisté à élaborer une base de données, de qualité et exploitable, en enregistrant de manière non invasive les signaux EMG à partir de matrices d’électrodes, et à la mettre en forme pour la mettre à disposition de la communauté scientifique. Dans un second temps, diverses approches de traitement du signal ont été mise en œuvre pour réduire la diaphonie. Au final, nous proposons une méthode basée sur la décomposition tensorielle non négative de type PARAFAC2 appliquée aux enveloppes des signaux EMG obtenues à partir de la RMS sur des fenêtres glissantes afin de séparer l’activité de chaque muscle. L’originalité du modèle proposé repose sur l’ajout de deux contraintes principales en plus de celles relatives à PARAFAC2. La première contrainte est liée à la physiologie musculaire et implique la continuité spatiale des cartes d’acquisition, tandis que la seconde contrainte est relative à notre protocole expérimental et introduit de la parcimonie. Le modèle a été testé et validé sur des signaux réels puis sur des mélanges artificiels de signaux réels. La méthode proposée offre de meilleures performances de séparation par rapport à l’algorithme NN-PARAFAC2 et plus généralement par rapport à l’ensemble des autres méthodes de séparation de sources classiquement utilisées. Les limites et perspectives sont envisagées dans la dernière partie du documentThe use of surface electromyographic (EMG) signals in a biomechanical, therapeutic, or control perspective requires a high spatial selectivity of the signals. In the case of adjacent muscles, this constraint is rarely met, making EMG signal utilization challenging. Crosstalk, or signal contamination inherent in recordings, must be eliminated.This thesis aims to propose methods for separating crosstalk when the extensor muscles of the index and little finger contract simultaneously. Our work focuses on extracting the muscle activity associated with each muscle in a source separation context. To achieve this, the initial part of the work involved creating a high-quality and usable database by non-invasively recording EMG signals from electrode arrays and formatting it for the scientific community's use. In the next phase, various signal processing approaches were employed to reduce crosstalk. Ultimately, we present a method based on non-negative tensor decomposition of the PARAFAC2 type applied to the envelopes of EMG signals obtained through root mean square (RMS) on sliding windows to separate the activity of each muscle. The uniqueness of the proposed model lies in the addition of two primary constraints in addition to those associated with PARAFAC2. The first constraint is related to muscle physiology and involves spatial continuity in the acquisition maps, while the second constraint is specific to our experimental protocol and introduces sparsity.The model was tested and validated on real signals and artificial mixtures of real signals. The proposed method demonstrates superior separation performance compared to the NN-PARAFAC2 algorithm and, more broadly, relative to conventional source separation methods. The document concludes by discussing its limitations and potential future directions
28
Rababy, Nada. "Estimation of EMG conduction velocity using system identification." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63819.
29
Cheng, Lui. "Improvement of signal-to-noise ratio in uterine EMG recordings." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/1548.
Abstract:
The objective of this study is to remove or, at least, reduce the noise in uterine EMG recordings, which at their present noise level render the data unusable. Predicting when true labor will start and recognizing when labor actually starts are important for both normal and complex pregnancies. For normal pregnancy, the prognosis of labor is important for reducing unnecessary hospital costs. About 10% of the four million babies born each year in the United States are born prematurely. At $1,500 a day for neonatal intensive care, this comprises national health care expenses of well over $5 billion. Spectral analysis, filter design, and 1/3 octave analysis were applied to analyze the uterine EMG recordings. Signal-to-noise ratio was increased with IIR Butterworth bandstop filter. The spectral band between 0.25 and 0.4 Hz shows matching of the Toco belt via spectral analysis. Nevertheless, 1/3 octave analysis gives the highest correct detection percentage compare with frequency analysis and filter design.
30
Tortopidis, Dimitrios Steliou. "Bite force and EMG studies on the jaw-closing muscles." Thesis, University of Glasgow, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361012.
31
Zbořilová, Nicol. "Mobilní EMG modul pro využití v terapii." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-241999.
Abstract:
This thesis explains structure of skeletal muscles, generation of action potencial and principle of muscle contraction. Further it shows types of electromyographic signal recording and its usage in therapy. Technical aspects of EMG signal and components required for electromyograph assemblage are next topic of this thesis. Another part presents design of simple EMG module for therapeutical application with bluetooth 4.0 interface.
32
Kaya, Ryan D. "Muscle Strength, Motor Units, and Aging." Ohio University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1365769270.
33
Sachs, Christina Michelle. "EMG analysis of type IIb muscle fibers correlated with blood lactate accumulation /." free to MU campus, to others for purchase, 2003. http://wwwlib.umi.com/cr/mo/fullcit?p1418061.
34
Platt, Ronald S. "Signal properties of respiratory muscle electromyograms." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0019/NQ47909.pdf.
35
Raghavendra, Jammalamadaka. "Optomyography: Detection of muscle surface displacement using reflective photo resistor." Thesis, KTH, Skolan för teknik och hälsa (STH), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-159204.
Abstract:
A human body can carry out many physiological complex processes which can be mechanical, electrical or bio-chemical. Each mechanical activity generates a signal that describes the characteristics of the particular action in the form of pressure or temperature. Any irregularity in the process changes the usual functioning thus affecting the performance of the system. Several techniques were introduced to evaluate these muscular signals in order to get a deeper understanding of the medical abnormalities. Displacement sensors, laser optics, electrodes, accelerometers and microphones are some of the widely used devices in measuring the electrical and mechanical activities produced in the muscles. The aim of this thesis project was to find and implement a simple non-contact optical method to measure and monitor the displacements caused on the surface of the skin due to muscular movements. In this study, a device was developed using photo electric sensors that can record surface changes caused on the skin due to the movements forearm muscles.Människokroppens aktiviteter genererar olika mätbara signaler som kan vara biokemiska, elektriska, mekaniska. Naturligtvis är det viktigt att kunna mäta dessa signaler för att kunna veta om kroppens olika organ fungerar som de ska göra eller inte. När det gäller rent mekaniska aktiviteter genereras signaler av olika typer som beskriver denna aktivitet, såsom tryck, temperatur och förflyttning. Om en sådan process avviker från det normala fallet, kommer kroppssystemets prestanda att försämras. Ett antal tekniker utvecklades för att kunna mäta dessa signaler och uppnå djupare förståelse av möjliga icke-normala medicinska konsekvenser. Förflyttningssensorer, laser optik, elektroder, accelerometrar och mikrofoner är exempel på mättekniker som används för att studera elektrisk och mekanisk aktivitet i muskelvävnader. Målet med detta arbete är att hitta, utveckla och implementera en enkel, användarvänlig, beröringsfri, optisk teknik för att mäta och studera de ytliga förflyttningar som förändrar hudytans landskap och resulterar från muskelaktiviteter och rörelser. Detta projekt resulterade i en enkel prototyp för ett mätinstrument som ser ut som ett armband med två fotoelektriska sensorer som används för att mäta hudytans förändringar på grund av olika arm- och handrörelser.
36
Rasheed, Sarbast. "A Multiclassifier Approach to Motor Unit Potential Classification for EMG Signal Decomposition." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/934.
Abstract:
EMG signal decomposition is the process of resolving a composite EMG signal into its constituent motor unit potential trains (classes) and it can be configured as a classification problem. An EMG signal detected by the tip of an inserted needle electrode is the superposition of the individual electrical contributions of the different motor units that are active, during a muscle contraction, and background interference.
This thesis addresses the process of EMG signal decomposition by developing an interactive classification system, which uses multiple classifier fusion techniques in order to achieve improved classification performance. The developed system combines heterogeneous sets of base classifier ensembles of different kinds and employs either a one level classifier fusion scheme or a hybrid classifier fusion approach.
The hybrid classifier fusion approach is applied as a two-stage combination process that uses a new aggregator module which consists of two combiners: the first at the abstract level of classifier fusion and the other at the measurement level of classifier fusion such that it uses both combiners in a complementary manner. Both combiners may be either data independent or the first combiner data independent and the second data dependent. For the purpose of experimentation, we used as first combiner the majority voting scheme, while we used as the second combiner one of the fixed combination rules behaving as a data independent combiner or the fuzzy integral with the lambda-fuzzy measure as an implicit data dependent combiner.
Once the set of motor unit potential trains are generated by the classifier fusion system, the firing pattern consistency statistics for each train are calculated to detect classification errors in an adaptive fashion. This firing pattern analysis allows the algorithm to modify the threshold of assertion required for assignment of a motor unit potential classification individually for each train based on an expectation of erroneous assignments.
The classifier ensembles consist of a set of different versions of the Certainty classifier, a set of classifiers based on the nearest neighbour decision rule: the fuzzy k-NN and the adaptive fuzzy k-NN classifiers, and a set of classifiers that use a correlation measure as an estimation of the degree of similarity between a pattern and a class template: the matched template filter classifiers and its adaptive counterpart. The base classifiers, besides being of different kinds, utilize different types of features and their performances were investigated using both real and simulated EMG signals of different complexities. The feature sets extracted include time-domain data, first- and second-order discrete derivative data, and wavelet-domain data.
Following the so-called overproduce and choose strategy to classifier ensemble combination, the developed system allows the construction of a large set of candidate base classifiers and then chooses, from the base classifiers pool, subsets of specified number of classifiers to form candidate classifier ensembles. The system then selects the classifier ensemble having the maximum degree of agreement by exploiting a diversity measure for designing classifier teams. The kappa statistic is used as the diversity measure to estimate the level of agreement between the base classifier outputs, i. e. , to measure the degree of decision similarity between the base classifiers. This mechanism of choosing the team's classifiers based on assessing the classifier agreement throughout all the trains and the unassigned category is applied during the one level classifier fusion scheme and the first combiner in the hybrid classifier fusion approach. For the second combiner in the hybrid classifier fusion approach, we choose team classifiers also based on kappa statistics but by assessing the classifiers agreement only across the unassigned category and choose those base classifiers having the minimum agreement.
Performance of the developed classifier fusion system, in both of its variants, i. e. , the one level scheme and the hybrid approach was evaluated using synthetic simulated signals of known properties and real signals and then compared it with the performance of the constituent base classifiers. Across the EMG signal data sets used, the hybrid approach had better average classification performance overall, specially in terms of reducing the number of classification errors.
37
Loudon, Gareth. "Advances in knowledge based signal processing : a case study in EMG decomposition." Thesis, University of Leicester, 1991. http://hdl.handle.net/2381/34799.
Abstract:
This thesis relates to the use of knowledge based signal processing techniques in the decomposition of EMG signals. The aim of the research is to fully decompose EMG signals recorded at fairly high force levels (up to twenty percent maximum voluntary contraction) automatically into their constituent motor unit potentials to provide a fast and accurate analysis routine for the clinician. This requires the classification of non-overlapping motor unit action potentials (MUAPs) and superimposed waveforms formed from overlapping MUAPs in the signal. Firstly, digital filtering algorithms are used to reduce noise in the signal. A normalisation and compression of the filtered signal is then performed to reduce the time of the analysis. Non-overlapping MUAPs are classified using a statistical pattern recognition method. The method first describes the MUAPs by a set of features and then uses diagonal factor analysis to form uncorrelated factors from these features. An adaptive clustering technique groups together MUAPs from the same MU using the uncorrelated factors. The decomposition of superimposed waveforms is divided into two sections. The first section is a procedural method that finds a reduced set of all possible combinations of MUAPs which are capable of forming each superimposed waveform. The second section is a knowledge based analysis of the selected MUAP combinations forming each superimposed waveform. An expert system has been designed to decide which combination is the most probable by studying the motor unit firing statistics and performs uncertainty reasoning based on fuzzy set theory. The decomposition method was tested on real and simulated EMG data recorded at different levels of maximum voluntary contraction. The different EMG signals contained up to six motor units (MUs). The new decomposition program decomposed all MUAPs in the EMG signals tested into their constituent MUs with an accuracy always greater than ninety five percent. The decomposition program takes about fifteen seconds to classify all non-overlapping MUAPs in an EMG signal of length one second and on average, an extra nine seconds to classify every superimposed waveform. Hardware limitations did not enable the testing of EMG signals containing more than six MUs. The results also show that the computer analysis can simulate the reasoning of a human expert when studying a complex EMG signal.
38
Sahlén, Adam. "Muscle activity in m.pectoralis major during bench press variations in healthy young males." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-29361.
Abstract:
Background. The bench press is a commonly used resistance training exercise for targeting the chest musculature. During hypertrophy training, different variations of bench press are often used to isolate different segments (pars clavicularis, pars sternocostalis and pars abdominals) of the chest muscle m.pectoralis major. Commonly used variations of the bench press are decline bench press (less than 0° from horizontal) and incline bench press (more than 0° from horizontal). Some research has been done into these variations of bench angle and their effect on muscle activation; however other commonly used bench angles is yet to be investigated. Aim. The aim of this study was to examine if there were any difference in muscle activity in the three segments of m.pectoralis majors while performing three different barbell bench press variations with different bench angles to obtain a greater understanding of m.pectoralis major activation and possibly optimize hypertrophy training in above mentioned muscles segments. Method. 13 healthy male (age: 23± 3.8 year and BMI: 24.3 ±1.8 kg/m2) participated in this single group study. EMG was used to measure muscle activity in m.pectoralis major's three segments. Test subjects performed 1 set of 6 repetitions on each bench press variation at a relative load of 6RM. An maximal voluntary isometric contraction (MVIC) test was performed and set as 100 percent reference value for comparison muscle activity in various angles. Results. While performing the decline bench press and the incline bench press, the muscle activity in pars clavicularis displayed a strong trend of a lower muscle activity (decline: p= 0.055 and incline: p=0.052) in comparison to the flat bench press. Muscle activity in pars sternocostalis while performing the incline bench press was significantly lower in comparison to the flat bench press (flat: p<0.001 and decline: p<0.001). Muscle activity in pars abdominals while performing the decline bench press was significantly higher (p=0.013) in comparison to the flat bench press. Muscle activity in pars abdominals while performing the incline bench press were significantly lower than both the flat and decline bench press (incline: p<0.001 and decline: p<0.001). Conclusion. For a better isolation of the pars abdominals segment, the decline bench press should be used. Muscle activity in pars sternocostalis did not show any significant difference between flat and decline bench press and could be isolated with either of these two exercises. The muscle activity in pars clavicularis showed a strong trend of higher activity while performing the flat bench press compared to the decline and incline bench press, however findings regarding the pars clavicularis differs between studies.
39
Rajotte, Kiriaki J. "Electromyogram (EMG) Signal Analysis: Extraction of a Novel EMG Feature and Optimal Root Difference of Squares (RDS) Processing in Additive Noise." Digital WPI, 2019. https://digitalcommons.wpi.edu/etd-theses/1339.
Abstract:
Electromyogram signals generated by human muscles can be measured on the surface of the skin and then processed for use in applications such as prostheses control, kinesiology and diagnostic medicine. Most EMG applications extract an estimate of the EMG amplitude, defined as the time-varying standard deviation of EMG, EMGσ. To improve the quality of EMGσ, additional signal processing techniques, such as whitening, noise reduction and additional signal features can be incorporated into the EMGσ processing. Implementation of these additional processing techniques improve the quality of the processed signal but at the cost of increased computational complexity and required calibration contractions. Whitening filters are employed to temporally decorrelate data so that the samples are statistically independent. Different types of whitening filters, linear and adaptive, and their performance have been previously studied in (Clancy and Hogan) and (Clancy and Farry). The linear filter fails at low effort levels and the adaptive filter requires a calibration every time electrodes are removed and reapplied. With the goal of avoiding the disadvantages of the previous whitening filter approaches, the first signal processing technique studied herein developed a universal fixed whitening filter using the ensemble mean of the power spectrum density of EMG recordings from the 64 subjects available in an existing data set. Performance of the EMG to torque model with the universal fixed whitening filter was computed to be 4.8% maximum voluntary contraction (MVC); this is comparable to the 4.84 %MVC error computed for the adaptive whitening filter. The universal fixed whitening filter preserves the performance of the adaptive filter but need not be calibrated for each electrode. To optimize noise reduction, the second signal processing technique studied derived analytical models using the resting EMG data. The probability density function of the rest contractions was observed to be very close to a Gaussian distribution, showing only a 1.6% difference when compared to a Gaussian distribution. Once the models were developed, they were used to prove that the optimal subtraction of the noise variance is to compute the root of the difference between the signal squared and noise variance (RDS). If this result would lead to a negative value, it must be set to zero; EMGσ cannot contain negative components. Once the RDS was proven to be the optimal noise subtraction, it was implemented on 0% MVC and 50% MVC data. The RDS processing has a considerable impact on lower level contractions (0% MVC), but not on higher level contractions (50% MVC), as expected. The third signal processing technique involved the creation of a new EMG feature from four individual signal features. Different techniques were used to combine EMGσ, zero crossings (ZC), slope sign changes (SSC) and waveform length (WL) into a single new EMG feature that would be used in an end application, such as the modeling of torque about the elbow or prosthesis control. The new EMG feature was developed to reduce the variance of the traditional EMGσ only feature and to eliminate the need for calibration contractions. Five different methods of combination were attempted, but none of the new EMG features improved performance in EMG to torque model.
40
Hewitt, G. "A study of developmental and intersubject differences in the use of EMG biofeedback to improve voluntary control of precise, directional contractions... frontalis muscles : Implications for clinical use." Thesis, Roehampton University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382549.
41
Hoeven, Johannes Harmen van der. "Conduction velocity in human muscle an EMG study in fatigue and neuromuscular disorders /." [S.l. : [Groningen] : s.n.] ; [University Library Groningen] [Host], 1995. http://irs.ub.rug.nl/ppn/142995223.
42
Bene, Cheryl Renee. "Visually displayed-EMG biofeedback : training muscle relaxation in hearing impaired children :a thesis." Scholarly Commons, 1988. https://scholarlycommons.pacific.edu/uop_etds/505.
Abstract:
The purpose of the present study was to test the use of visually displayed EMG biofeedback as a means for training hearing impaired adolescents to reduce anterior temporalis or frontalis muscle tension . Five male and four female hearing impaired students between the ages of 13 and 15 were chosen from the California School for the Deaf, Fremont, CA to serve as participants. Each participant was randomly assigned to either an experimental or control condition. Participants in the experimental groups were given five 15 minute EMG biofeedback training sessions. An additional group of 4 adolescents with normal hearing from Marshall Junior High School, Stockton, CA served as a hearing control group. The dependent measure was a 5 minute pretest and post-test measurement of muscle tension (in microvolts).
Split-plot analyses were performed to determine if there were significant differences between a ) the .hearing impaired experimental and the hearing impaired control groups, b) the hearing impaired control and the hearing control groups, and c) the hearing impaired experimental group and the hearing control group.
Results of the analyses showed that at post-test both the hearing impaired experimental group and the hearing control group showed a significant decrease in muscle tension F(1,7)=5.85 p< .05. The interaction was nonsignificant. Comparison of the two control groups showed that at post-test the two groups were not significantly different in levels of muscle tension. The comparison between the hearing impaired experimental and the hearing control groups resulted in a significant interaction (Group X Time of Testing) F( 1,6)=9.47, p=.02, and the main effect for time of testing approached significance.
43
Szabó, Balázs. "High density EMG based estimation of lower limb muscle characteristics using feature extraction." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-289859.
Abstract:
Electromyography (EMG) is a common tool in electrical muscle activity measurement and can be used in multiple areas of clinical and biomedical applications, mainly in identifying neuromuscular diseases, analyzing movement or in human machine interfaces. Traditionally a pair of electrodes were used to measure the signals, but in recent years the use of high density surface EMG (HD-sEMG) gained more popularity as it can sample myoelectric activities from multiple electrodes in an array on a single muscle and provide more information. In this thesis a measurement setup and protocol is proposed that can provide a reliably measurement, furthermore multiple features are extracted from the collected signals to characterise the major muscles around the ankle. 5 healthy subjects were tested using an ankle dynamometer with 5 HD-sEMG placed on the Tibialis Anterior, the Gastrocnemius Medialis, the Soleus, the Gastrocnemius Lateralis, and on the Peroneus Longus. Several tests were conducted using different initial angle of the ankle joint and different percentages of the maximum voluntary contraction. The reliability of the setup was assessed by comparing the variance between the collected signals of the same subject in a repeated test, and by comparing different subjects to each other. Results show a reasonably good reliability with less than $10\%$ variance, and adequate selectivity as well. To examine the muscle characteristics, 7 features were extracted from the collected and processed signals, then the features were plotted and compared to signs for muscle characteristics such as muscle fatigue, activation, and spatial distribution of activation. Correlations between features of mean average value (MAV) and zero crossing (ZC), and different muscle characteristics could be observed.
44
Takahashi, Luciana Sanae Ota. "Análise da relação entre eletromiografia e força do músculo quadríceps em exercícios resistidos." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/82/82131/tde-30072007-172711/.
Abstract:
A relação entre eletromiografia e força é objeto de numerosos estudos, porém tal relação ainda não está totalmente elucidada e necessita de uma melhor fundamentação. Uma possível razão para as divergências entre esses estudos reside na dificuldade em determinar a força de um músculo individualmente de forma direta. Dentro deste contexto, procurou-se utilizar a análise do sinal eletromiográfico, associada a um modelo biomecânico do segmento articular para a avaliação das forças internas do músculo. O objetivo do presente trabalho é avaliar o comportamento eletromiográfico do músculo quadríceps durante exercícios isométricos e isotônicos concêntricos e correlacioná-lo com a força muscular, calculada através de simulações, usando modelos biomecânicos. Busca-se também uma forma de reconstruir a sobrecarga a que o músculo é submetido durante o exercício isotônico, através do tratamento do sinal eletromiográfico. Para tanto, o exercício isotônico é realizado em baixa velocidade e com pequena sobrecarga, e além disso, utiliza-se o procedimento de normalizar o sinal eletromiográfico ponto-a-ponto. Tal procedimento não possibilitou que a força externa, aplicada pelo membro, fosse obtida a partir do tratamento do sinal eletromiográfico, porém permitiu a correlação da eletromiografia com a força interna, gerada pelo músculo. Verificou-se também que a relação entre eletromiografia e força varia com a posição angular, com a força, com a velocidade de contração muscular e com a velocidade angular. No que se refere às análises da atividade isotônica, uma importante conclusão é que a relação entre eletromiografia e força não é linear; no entanto, quando normalizados pelos seus valores máximos podem ser considerados proporcionais.The relationship between electromyography and force is largely investigated, however, such relation is not yet fully understood, still requiring better foundation. One of the reasons that might cause discrepancies between studies lies on directly calculating a single muscle force. Our approach handles the electromyographic signal coupled with a biomechanical model of the joint for assessment of internal muscle forces. This study aims at an evaluation of electromyographic behavior of the quadriceps muscle throughout isometric and concentric exercises, relating it to muscle force calculated by means of simulations, using biomechanical models. It is also handled in our study a means of assessing muscle overloading throughout dynamic exercises using eletromiographic signals. Accordingly, the dynamic exercise is undergone at slow speed and low resistance; and the electromyographic signal is normalized angle by angle. The approach did not allow the external force, produced by the limb, be assessed by means of electromyographic treatment, however, it allowed a relation between electromyography with internal force produced by the limb. It is worth mentioning that the electromyography-force relationship undergoes variations according to angular position, to degree of force, to muscle contraction velocity, to angular velocity. As to isotonic activity analysis, one important conclusion is the relation between electromyography and force is non-linear, with the proviso, that when normalized by peak values electromyography and force may be considered proportional.
45
Anjos, Fabio Vieira Dos. "High-density surface EMG to investigate muscle activity during standing: implications for the training of postural control with EMG biofeedback in the elderly." Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2690493.
Abstract:
By recording surface EMG using standard bipolar EMG, previous studies have demonstrated that elderlies tend to activate their postural muscles during standing with a higher degree of activity and for a prolonged duration compared with young adults. The EMG biofeedback technique has been widely used to reduce the excessive level of muscle activity in different fields, e.g. the prevention and reduction of low back pain. In this view, EMG biofeedback could be a potential tool to assist aged subjects in reducing the excessive muscle activity during standing balance. However, whether the greater, prolonged activation observed locally in the muscles of aged subjects reflects the activation of the entire muscle is still an open question. It is possible that differences in the activation of postural muscles with aging are more or less expressive than previously appreciated. This thesis aimed at obtaining new insights into the rationale and the effects of the use of EMG biofeedback for the improvement of muscle efficiency during standing in the elderly. It was evaluated whether muscle activation during standing differ between young and aged subjects through a sophisticated detection system for the acquisition of surface EMGs from multiple regions of a single muscle (i.e., high-density surface EMG). Before to test this hypothesis, a methodological issue was addressed to verify whether high-density surface EMG is selective enough to detect during standing: (a) different activation between ankle muscles, as observed with other techniques (intramuscular electromyography); (b) variations in the activity within ankle muscles (i.e., soleus muscles). The results of this methodological study revealed that the medial portion of soleus muscle was activated continuously compared to the lateral portion of soleus and medial gastrocnemius, which were activated intermittently. These results suggest high-density surface EMGs can be used to discriminate the activity between ankle muscles (i.e., medial gastrocnemius and soleus) and muscle activity sampled from different regions of a single muscle (i.e., soleus) can provide estimates more representative of muscle activity during standing. High-density surface EMG was therefore used to assess muscle activity between young and aged subjects during standing. Key results indicate that during standing: (a) tibialis anterior and medial gastrocnemius muscles were active for a longer duration in aged than young subjects; (b) a greater proportion of medial gastrocnemius volume was active in aged individuals. Collectively, these results corroborate previous evidence that elderlies tend to stand with a greater muscle effort than young subjects. Thus, the well-documented attenuation effect of EMG biofeedback on muscle activity may extend to the control of human standing posture with aging. This thesis addressed additional issues which could be relevant to provide more representative EMGs of muscle activity to the subject through EMG biofeedback and to prove the attenuation effect of EMG biofeedback on the activity of lower limb muscles during standing. The following two questions were addressed: i) should EMGs be sampled from both lower limbs to provide more representative information about calf muscles activity? It was observed differences in muscle activity between left and right ankle muscle while young subjects stood at ease. These results indicate muscle activity should be sampled from the ankle muscles of both legs to avoid a biased recording and feedback of muscle activity during standing. ii) Is the attenuation effect of EMG biofeedback on the ankle muscles activity generalized to – or compensated by – other muscles during standing? These findings revealed the attenuation effect of EMG-audio feedback on ankle muscles is not compensated by other lower limbs muscles not included for the feedback. Therefore, the EMG biofeedback may be a promising technique to assist individuals in more efficiently controlling lower limbs muscles during standing. If the short-term, attenuation, effect of EMG-audio feedback on ankle muscles’ activity in young individuals observed here is generalized to other populations (e.g., the elderly) and retained after training, then, improvement in postural muscle efficiency may contribute significantly to an ability to maintain standing balance, to respond to unexpected perturbation, standing on narrow stances and walking; with potential implication for the prevention of falls.
46
Koenig, Alexander C. "Simulation of agonist and antagonist muscle activation patterns in bidirectional postural perturbation in cats." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11576.
Abstract:
We studied the effects of varying perturbation magnitude and direction on the postural control process of the central nervous system (CNS) caused by perturbation, before and after sensory loss. The electromyogram (EMG) response to a postural perturbation can be composed by a weighted sum of the center of mass (CoM) kinematics. We extended an existing CoM feedback model which predicted EMG of one muscle for unidirectional perturbations; we used recorded data of bidirectional perturbations, which caused muscle activity in anterior as well as posterior muscles. Modeling the CNS as two delayed feedback controllers, we reconstructed the EMGs of two antagonistic muscles simultaneously that were recorded during postural perturbation experiments on cats. Minimizing the error between predicted and recorded EMG and CoM kinematics, we were able to identify controller gains that would result in the best prediction of the recorded EMGs.
We hypothesized that the weights on the CoM kinematics remained constant independent of variations in perturbation magnitude or reversed perturbation direction. We applied our model to data from bidirectional perturbations with varying magnitude, with which the cats were perturbed for a short time in one direction and a longer time in the opposite direction.
The gains showed small variation for EMG predictions following long perturbations; however, the prediction of EMG following the initial displacement resulted in large gain variations. We showed that these variations were caused by our optimization methods, which was not able to consistently identify controller gains for short initial movements. Using the weights identified for unidirectional perturbations, we were able to predict muscle activity for both directions with the same gains. This suggests that the weights of the CoM kinematics for each muscle did not change for varying perturbation magnitude. We conclude that varying EMG shapes were induced solely by the variation of the CoM kinematics.
We repeated the investigations on data that was recorded from cats suffering from sensory loss and found reduced CoM acceleration feedback.
47
Pettersson, Victor. "Repetitive climbing effect on muscle activation." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-42144.
Abstract:
Background. Climbing is growing as a recreational sport worldwide. Climbing is a physically demanding sport requiring well developed strength and endurance. Plenty of studies have been made in the area of climbing in order to understand how the body adapts, which muscles are being used and how to prevent injury. A lot of these studies uses electromyography (EMG), a tool that measures electrical currents in muscles to detect muscle activity, as measurement method in order to do findings within the area. Aim. The aim was to study differences in muscle activation in arm and leg muscles in climbers before and after 40 repeated attempts over two weeks on a boulder problem. Furthermore, correlation between climbing level and change in total measured muscle activation after repeated attempts was assessed. Methods. 15 participants (five women and ten men) participated in this study. Standardized electrode placements and maximal voluntary isometric contractions (MVIC) were made for muscles; Flexor Carpi Radialis (FCR), Bicep Brachii (BB), Rectus Femoris (RF) and Gastrocnemius Lateralis (GL) before each measurement in order to maintain good reliability. Participants repeated a specific climbing route, adapted to the participants climbing ability, 40 times, divided into four sessions over two weeks. Before the first measured attempt the participant got to practice the route twice to get familiar with the moves. Average muscle activation was calculated by dividing the total muscle activation from each muscle with the time it took to complete the climbing route. Peak muscle values were calculated by dividing the highest muscle activation value with the MVIC values to get a %MVIC value. Results. A decrease in average muscle activation for FCR and BB were found (p=0.038, 0.023) whereas an increase in average activation for GL was found (p=0.027). Peak muscle activation showed significant decreases regarding upper extremities FCR and BB (p=0.008, p=0.011) but no significant changes to lower extremities RF and GL. Total average muscular activation regarding all muscles combined showed a general decreased activation (p=0.001). Moderate correlation was found between red-point level and decrease in total average muscle activation (r=0.53). Conclusion. When repeating a climbing route, the climbers muscle activation differs in upper and lower extremities, with a decrease in upper extremities peak and average muscle values, and an increase in GL average muscle values. Repetitions improves technique and muscle memory which could be the reason for the overall decrease in total muscle activation. Hopefully, this study could enrich the climbing world with further knowledge in how to train for climbing.
48
Lockhart, Daniel Bruce. "Prediction of Muscle Activation Patterns During Postural Control Using a Feedback Control Model." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7280.
Abstract:
Neural mechanisms determining temporal muscle activity patterns during postural control are not well understood. We hypothesize that a feedback control mechanism can predict both temporal extensor muscle EMG and CoM kinematics (acceleration, velocity, and displacement) during postural perturbations before and following peripheral neuropathy to group I afferents induced by pyridoxine intoxication. We introduce a feedback model for analyzing temporal EMG patterns that decomposes recorded electromyogram (EMG) signals into the sum of three center of mass (CoM) feedback components. EMG and CoM kinematics during postural responses due to support surface translations were measured before and 14 days after somatosensory loss in cats. We successfully predicted EMG before and after peripheral neuropathy by modeling a standing cat as an inverted pendulum and decomposing temporal EMG patterns using a simulation with time delayed feedback loop of CoM kinematics. This model accounts for over 60% of the total temporal variability of recorded extensor EMG patterns. Feedback gains for acceleration, velocity and position necessary to predict EMGs before and after sensory loss were different. For intact animals, more that 90% of the initial burst of EMG were due to CoM acceleration feedback, while later portions were due entirely to velocity and position feedback. After peripheral neuropathy, the initial burst was absent and the acceleration gain was significantly reduced when compared to the acceleration gain of intact animals for extensor muscles (p lt 0.05). By successfully decomposing EMG into three kinematic gains, a quantitative comparison of temporal EMG patterns before and after peripheral neuropathy is possible. The reduction of acceleration gain in sensory loss cats suggests that group I afferents provide necessary information that is used as acceleration feedback.
49
Peña, Guido Gómez. "Controle de impedância adaptativo dirigido por EMG para reabilitacão robótica." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/18/18149/tde-19032019-144320/.
Abstract:
Esta tese trata da estimativa de torque e rigidez do paciente dirigida por EMG e sua utilização para adaptar a rigidez do robô durante a reabilitação assistida por robôs. Os sinais eletromiográficos (EMG), obtidos de músculos que atuam durante os movimentos de flexão e extensão de um usuário utilizando uma órtese de joelho ativa, são processados para obter as ativações dos músculos. Inicialmente, um modelo musculoesquelético simplificado e otimizado é usado para calcular as estimativas de torque e rigidez da junta do paciente. A otimização do modelo é realizada comparando o torque estimado com o torque gerado pela ferramenta de dinâmica inversa do software OpenSim, considerando um modelo musculoesquelético escalonado. Como uma solução complementar, é proposta uma rede neural perceptron multicamada (NN) para mapear os sinais EMG para o torque do paciente. Também é apresentado um Ambiente de Estimativa de Torque Gerado por EMG criado para analisar os dados obtidos a partir da aplicação das abordagens propostas considerando a aplicação de um protocolo criado para a análise de interação usuário-exoesqueleto. Um banco de dados de indivíduos saudáveis também foi disponibilizado neste trabalho. Além disso, uma estratégia de controle de impedância adaptativa é proposta para ajustar a rigidez do robô com base na estimativa de rigidez do paciente por EMG. A estratégia inclui uma solução ideal para a interação paciente-robô. Finalmente, são apresentados os resultados obtidos aplicando o controle de impedância adaptativo proposto durante os movimentos de flexão e extensão do usuário que usa a órtese ativa.This thesis deals with EMG-driven patient torque and stiffness estimation and its use to adapt the robot stiffness during robot-aided rehabilitation. Electromyographic (EMG) signals, taken from selected muscles acting during flexion and extension movements of an user wearing an active knee orthosis, are processed to get the muscles activations. First, a simplified and optimized musculoskeletal model is used to compute the estimate of patient joint torque and stiffness. The model optimization is performed by comparing the estimate torque with the torque generated by the inverse dynamics tool of the OpenSim software, considering a scaled musculoskeletal model. As a complementary solution, a multilayer perceptron neural network (NN) is proposed to map the EMG signals to the patient torque. It is also presented an EMG-driven Torque Estimation Environment created to analyze the data obtained from the application of the proposed approaches considering a protocol created for user-exoskeleton interaction analysis. A database with data from 5 healthy subjects is also made available in this work. Additionally, an adaptive impedance control strategy is proposed to adjust the robot stiffness based on the EMG-driven patient stiffness estimation. The strategy includes an optimal solution for the patient-robot interaction. Finally, the results obtained by applying the proposed adaptive impedance control during flexion and extension movements of the user wearing the active orthosis are presented.
50
Wang, Shuqiang. "A framework for medical decision support systems : a case study of EMG signal interpretation." Thesis, University of Leicester, 1995. http://hdl.handle.net/2381/34721.
Abstract:
This thesis contains a framework of medical decision support systems (DSS) and a case study of signal interpretation in electromyography (EMG). Methodologies required for architecture of such knowledge-based systems (KBS) are explored at both epistemological level and computational level in the thesis. Firstly, a research scheme is proposed under which system development is explicitly defined as a process of two stages, conceptual design and computational design. The conceptual design is mainly concerned with the medical domain. Its task is to abstract the problem-solving logic of that domain into symbolic forms of models. The computational design deals with more concrete issues related to system implementation and information technology (IT). Its task is to create applicable computing models in light of the conceptual system models. Object-oriented analysis (OOA) is introduced into the process of system analysis and design. At conceptual level, three fundamental inference patterns, forward reasoning (FR), backward reasoning (BR) and induction reasoning (IR), are abstracted as basic building blocks of domain problem-solving. Medical domain problem-solving can therefore be modelled as a hierarchical process made from the three basic patterns. A scheme extracted from a number of blackboard systems is determined as the framework's general problem-solving scenario. The blackboard scheme is then defined as a complex of interacting objects. At computational design, various computing algorithms are reviewed which range from object-oriented design (OOD), knowledge representation, uncertainty-handling to user-system interface. Decision strategies are also investigated in the context of EMG interpretation. The logic of medical decisions is revealed as a process of heuristic search and probabilistic thinking by Bayes' theorem. Decision-making is therefore modelled as a hierarchical process that combines inference reasoning and uncertainty-handling. An inference engine is designed using fuzzy logic and a decision network. It employs the decision principles of Bayes' theorem, but applies more realistic strategies of uncertainty-handling and inference. A preliminary EMG interpretation system is built under the framework. It is evaluated via a simulation study. The general methodology presented by the framework is shown to be a promising approach to system transparency, efficiency and performance.