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La consolidation est le processus qui transforme une nouvelle trace mnésique labile en ‎une autre plus stable et plus solide. Une des tâches utilisées en laboratoire pour ‎l’exploration de la consolidation motrice dans ses dimensions comportementale et ‎cérébrale est la tâche d’apprentissage de séquences motrices. Celle-ci consiste à ‎reproduire une même série de mouvements des doigts, apprise de manière implicite ou ‎explicite, tout en mesurant l’amélioration dans l’exécution. Les études récentes ont ‎montré que, dans le cas de l’apprentissage explicite de cette tâche, la consolidation de la ‎trace mnésique associée à cette nouvelle habileté dépendrait du sommeil, et plus ‎particulièrement des fuseaux en sommeil lent. Et bien que deux types de fuseaux aient ‎été décrits (lents et rapides), le rôle de chacun d’eux dans la consolidation d’une ‎séquence motrice est encore mal exploré. En effet, seule une étude s’est intéressée à ce ‎rôle, montrant alors une implication des fuseaux rapides dans ce processus mnésique ‎suite à une nuit artificiellement altérée. D’autre part, les études utilisant l’imagerie ‎fonctionnelle (IRMf et PET scan) menées par différentes équipes dont la notre, ont ‎montré des changements au niveau de l’activité du système cortico-striatal suite à la ‎consolidation motrice. Cependant, aucune corrélation n’a été faite à ce jour entre ces ‎changements et les caractéristiques des fuseaux du sommeil survenant au cours de la nuit ‎suivant un apprentissage moteur. Les objectifs de cette thèse étaient donc: 1) de ‎déterminer, à travers des enregistrements polysomnographiques et des analyses ‎corrélationnelles, les caractéristiques des deux types de fuseaux (i.e. lents et rapides) ‎associées à la consolidation d’une séquence motrice suite à une nuit de sommeil non ‎altérée, et 2) d’explorer, à travers des analyses corrélationnelles entre les données ‎polysomnographiques et le signal BOLD (« Blood Oxygenated Level Dependent »), ‎acquis à l’aide de l’imagerie par résonance magnétique fonctionnelle (IRMf), ‎l’association entre les fuseaux du sommeil et les activations cérébrales suite à la ‎consolidation de la séquence motrice. Les résultats de notre première étude ont montré ‎une implication des fuseaux rapides, et non des fuseaux lents, dans la consolidation ‎d’une séquence motrice apprise de manière explicite après une nuit de sommeil non ‎altérée, corroborant ainsi les résultats des études antérieures utilisant des nuits de ‎sommeil altérées. En effet, les analyses statistiques ont mis en évidence une ‎augmentation significative de la densité des fuseaux rapides durant la nuit suivant ‎l’apprentissage moteur par comparaison à la nuit contrôle. De plus, cette augmentation ‎corrélait avec les gains spontanés de performance suivant la nuit. Par ailleurs, les ‎résultats de notre seconde étude ont mis en évidence des corrélations significatives entre ‎l’amplitude des fuseaux de la nuit expérimentale d’une part et les gains spontanés de ‎performance ainsi que les changements du signal BOLD au niveau du système cortico-‎striatal d’autre part. Nos résultats suggèrent donc un lien fonctionnel entre les fuseaux ‎du sommeil, les gains de performance ainsi que les changements neuronaux au niveau ‎du système cortico-striatal liés à la consolidation d’une séquence motrice explicite. Par ‎ailleurs, ils supportent l’implication des fuseaux rapides dans ce type de consolidation ; ‎ceux-ci aideraient à l’activation des circuits neuronaux impliqués dans ce processus ‎mnésique et amélioreraient par la même occasion la consolidation motrice liée au ‎sommeil.‎ / Motor memory consolidation refers to brain plasticity processes resulting in enduring ‎long-term changes in the neural representations of the learned experiences. One of the ‎paradigms used in the laboratory to study motor consolidation in both its behavioral and ‎neuronal dimensions is the motor sequence learning task. The latter consists in executing ‎the same series of implicitly or explicitly learned movements, and then in looking at the ‎subsequent spontaneous improvement in performance after a period of time without ‎additional practice. On one hand, recent studies have shown that in the case of explicit ‎motor sequence learning, consolidation highly correlated with sleep, and more ‎particularly with N-REM sleep spindles. Even though two types of spindles have been ‎identified (fast and slow spindles), the role of these two sleep features in the ‎consolidation of motor sequence learning is still unclear. In fact, only one study explored ‎this role through artificially altered nights, showing an implication of fast spindles in this ‎process. On the other hand, several functional imaging studies (using functional ‎magnetic resonance imaging [fMRI] and positron emission tomography [PET] scans), ‎have shown changes in the activity of the cortico-striatal system following the ‎consolidation of an explicitly learned motor sequence. But to this day, no study has yet ‎investigated the relationship between these brain functional changes and the sleep ‎spindles characteristics occurring during the night following the experimental task. The ‎objectives of this study were thus: 1) to determine, through polysomnographic ‎recordings and correlation analysis, the contribution of the two spindle types (i.e. slow ‎and fast) to the consolidation of a newly learned motor sequence task following an ‎unaltered night of sleep, and 2) to explore through correlation analysis, the association ‎between sleep spindles and neuronal changes that occur during consolidation of this ‎motor skill. The results of our first study showed that fast, but not slow, sleep spindles ‎play a role in the motor memory consolidation process. Indeed, statistical analyses ‎revealed a significant increase in the density of fast spindles during the night following ‎the motor sequence learning when compared to the control night. Furthermore, this ‎increase in spindles correlated with the spontaneous gains in performance following ‎sleep. Interestingly, the results of our second study revealed correlations between the ‎amplitude of the spindles during the experimental night on the one hand, the amount of ‎spontaneous gains in performance overnight as well as the changes in the BOLD signal ‎within the cortico-striatal system on the other hand. Taken together, our results suggest a ‎functional link between sleep spindles and both overnight gains in performance and ‎brain correlates reflecting motor memory consolidation of a newly acquired sequence of ‎movements. They also support the notion that fast spindles seem to play a more ‎prominent role in this consolidation process, as they appear to help activate the cerebral ‎network involved in it and thus to improve sleep-dependent motor memory ‎consolidation.‎

La consolidation est le processus qui transforme une nouvelle trace mnésique labile en ‎une autre plus stable et plus solide. Une des tâches utilisées en laboratoire pour ‎l’exploration de la consolidation motrice dans ses dimensions comportementale et ‎cérébrale est la tâche d’apprentissage de séquences motrices. Celle-ci consiste à ‎reproduire une même série de mouvements des doigts, apprise de manière implicite ou ‎explicite, tout en mesurant l’amélioration dans l’exécution. Les études récentes ont ‎montré que, dans le cas de l’apprentissage explicite de cette tâche, la consolidation de la ‎trace mnésique associée à cette nouvelle habileté dépendrait du sommeil, et plus ‎particulièrement des fuseaux en sommeil lent. Et bien que deux types de fuseaux aient ‎été décrits (lents et rapides), le rôle de chacun d’eux dans la consolidation d’une ‎séquence motrice est encore mal exploré. En effet, seule une étude s’est intéressée à ce ‎rôle, montrant alors une implication des fuseaux rapides dans ce processus mnésique ‎suite à une nuit artificiellement altérée. D’autre part, les études utilisant l’imagerie ‎fonctionnelle (IRMf et PET scan) menées par différentes équipes dont la notre, ont ‎montré des changements au niveau de l’activité du système cortico-striatal suite à la ‎consolidation motrice. Cependant, aucune corrélation n’a été faite à ce jour entre ces ‎changements et les caractéristiques des fuseaux du sommeil survenant au cours de la nuit ‎suivant un apprentissage moteur. Les objectifs de cette thèse étaient donc: 1) de ‎déterminer, à travers des enregistrements polysomnographiques et des analyses ‎corrélationnelles, les caractéristiques des deux types de fuseaux (i.e. lents et rapides) ‎associées à la consolidation d’une séquence motrice suite à une nuit de sommeil non ‎altérée, et 2) d’explorer, à travers des analyses corrélationnelles entre les données ‎polysomnographiques et le signal BOLD (« Blood Oxygenated Level Dependent »), ‎acquis à l’aide de l’imagerie par résonance magnétique fonctionnelle (IRMf), ‎l’association entre les fuseaux du sommeil et les activations cérébrales suite à la ‎consolidation de la séquence motrice. Les résultats de notre première étude ont montré ‎une implication des fuseaux rapides, et non des fuseaux lents, dans la consolidation ‎d’une séquence motrice apprise de manière explicite après une nuit de sommeil non ‎altérée, corroborant ainsi les résultats des études antérieures utilisant des nuits de ‎sommeil altérées. En effet, les analyses statistiques ont mis en évidence une ‎augmentation significative de la densité des fuseaux rapides durant la nuit suivant ‎l’apprentissage moteur par comparaison à la nuit contrôle. De plus, cette augmentation ‎corrélait avec les gains spontanés de performance suivant la nuit. Par ailleurs, les ‎résultats de notre seconde étude ont mis en évidence des corrélations significatives entre ‎l’amplitude des fuseaux de la nuit expérimentale d’une part et les gains spontanés de ‎performance ainsi que les changements du signal BOLD au niveau du système cortico-‎striatal d’autre part. Nos résultats suggèrent donc un lien fonctionnel entre les fuseaux ‎du sommeil, les gains de performance ainsi que les changements neuronaux au niveau ‎du système cortico-striatal liés à la consolidation d’une séquence motrice explicite. Par ‎ailleurs, ils supportent l’implication des fuseaux rapides dans ce type de consolidation ; ‎ceux-ci aideraient à l’activation des circuits neuronaux impliqués dans ce processus ‎mnésique et amélioreraient par la même occasion la consolidation motrice liée au ‎sommeil.‎ / Motor memory consolidation refers to brain plasticity processes resulting in enduring ‎long-term changes in the neural representations of the learned experiences. One of the ‎paradigms used in the laboratory to study motor consolidation in both its behavioral and ‎neuronal dimensions is the motor sequence learning task. The latter consists in executing ‎the same series of implicitly or explicitly learned movements, and then in looking at the ‎subsequent spontaneous improvement in performance after a period of time without ‎additional practice. On one hand, recent studies have shown that in the case of explicit ‎motor sequence learning, consolidation highly correlated with sleep, and more ‎particularly with N-REM sleep spindles. Even though two types of spindles have been ‎identified (fast and slow spindles), the role of these two sleep features in the ‎consolidation of motor sequence learning is still unclear. In fact, only one study explored ‎this role through artificially altered nights, showing an implication of fast spindles in this ‎process. On the other hand, several functional imaging studies (using functional ‎magnetic resonance imaging [fMRI] and positron emission tomography [PET] scans), ‎have shown changes in the activity of the cortico-striatal system following the ‎consolidation of an explicitly learned motor sequence. But to this day, no study has yet ‎investigated the relationship between these brain functional changes and the sleep ‎spindles characteristics occurring during the night following the experimental task. The ‎objectives of this study were thus: 1) to determine, through polysomnographic ‎recordings and correlation analysis, the contribution of the two spindle types (i.e. slow ‎and fast) to the consolidation of a newly learned motor sequence task following an ‎unaltered night of sleep, and 2) to explore through correlation analysis, the association ‎between sleep spindles and neuronal changes that occur during consolidation of this ‎motor skill. The results of our first study showed that fast, but not slow, sleep spindles ‎play a role in the motor memory consolidation process. Indeed, statistical analyses ‎revealed a significant increase in the density of fast spindles during the night following ‎the motor sequence learning when compared to the control night. Furthermore, this ‎increase in spindles correlated with the spontaneous gains in performance following ‎sleep. Interestingly, the results of our second study revealed correlations between the ‎amplitude of the spindles during the experimental night on the one hand, the amount of ‎spontaneous gains in performance overnight as well as the changes in the BOLD signal ‎within the cortico-striatal system on the other hand. Taken together, our results suggest a ‎functional link between sleep spindles and both overnight gains in performance and ‎brain correlates reflecting motor memory consolidation of a newly acquired sequence of ‎movements. They also support the notion that fast spindles seem to play a more ‎prominent role in this consolidation process, as they appear to help activate the cerebral ‎network involved in it and thus to improve sleep-dependent motor memory ‎consolidation.‎

Οι διάφορες δραστηριότητες του εγκεφάλου συχνά χαρακτηρίζονται από ειδικούς ρυθμούς στο ηλεκτροεγκεφαλογράφημα (ΗΕΓ). Το 2ο στάδιο του ύπνου χωρίς ταχείες οφθαλμικές κινήσεις (στάδιο NREM) χαρακτηρίζεται από τις ατράκτους που σηματοδοτούν την ουσιαστική έναρξη του ύπνου. Αποτελούν 0.5-1 δευτερόλεπτα ρυθμικής διαδοχής κύρια αρνητικών κυμάτων γενικευμένα στο ΗΕΓ τα οποία παρουσιάζουν προϊούσα αύξηση και μετά μείωση του πλάτους τους. Οι άτρακτοι συμμετέχουν σε διάφορες σημαντικές λειτουργίες του εγκεφάλου. Η κατανόηση του πολύπλευρου και πολύ σημαντικού ρόλου των ατράκτων έχει αποτελέσει αφορμή ώστε να γίνουν προσπάθειες εντοπισμού των υπεύθυνων για τη γένεσή τους εγκεφαλικών κυκλωμάτων. Σκοπός της προτεινόμενης μεθόδου είναι η εφαρμογή της μεθόδου εντοπισμού σημάτων σε πολυκαναλικές καταγραφές χρησιμοποιώντας περιορισμούς που στηρίζονται στο πεδίο του χώρου (spatial constraints) και το πεδίο της συχνότητας (frequency constraints) χρησιμοποιώντας την τεχνική ανάλυσης σε ανεξάρτητες συνιστώσες (ICA). Η μέθοδος εφαρμόστηκε για την ανάλυση βραδέων και ταχέων ατράκτων σε εγκεφαλογραφήματα ύπνου. Στο εργαστήριο Φυσιολογίας έχουν γίνει ΗΕΓ καταγραφές ολονύκτιου ύπνου με καταμέτρηση πολλών εκατοντάδων ατράκτων οι οποίες χρησιμοποιήθηκαν για την ανάπτυξη της παραπάνω μεθόδου αυτομάτου ανίχνευσης και εντοπισμού των ατράκτων. / Several brain activities are characterized by specific rhythms in electroencephalogram (EEG). The non rapid eye movement (NREM) stage of sleep is characterized by sleep spindles signaling the beginning of sleep. Spindles are rhythmic generalized negative waves in EEG with progressively increasing and gradually decreasing amplitude lasting 0.5-1 sec. Spindles are involved in several brain functions. The comprehension of the significance and multilateral role of spindles has driven efforts to detect the brain circuits involved in their generation. The purpose of this study is the introduction of a signal detection method in multichannel records, using Independent Component Analysis with spatial and frequency constraints. This automatic detection method was applied to the analysis of fast and slow spindles in sleep EEG, obtained from whole-night sleep recording in the laboratory of Physiology Department at University of Patras.

Uma vibração aplicada a um tendão muscular aumenta a freqüência de disparos de aferentes, como os de fusos neuromusculares Ia e II, cujas terminações afetam circuitos da medula espinhal e com isto podem influenciar o controle motor. O objetivo deste estudo foi analisar o efeito de vibrações a duas freqüências (15 e 80Hz) e amplitudes de 1 e 2,5mm aplicadas ao tendão calcâneo direito sobre o sistema de controle postural e sobre a circuitaria neural associada a reflexos monosinápticos da perna. A hipótese era de que a vibração de alta freqüência ativasse preferencialmente os aferentes de fuso neuromuscular de tipo Ia enquanto a vibração a 15 Hz ativasse preferencialmente os aferentes de tipo II. Isto significaria que a vibração a 80 Hz teria forte efeito sobre o reflexo H, enquanto a vibração a 15 Hz teria um efeito significativo sobre a postura. Participaram deste estudo 14 sujeitos sãos. Na postura ereta quieta, foi realizada a aquisição do reflexo H enquanto o tendão calcâneo era vibrado. Após um intervalo de descanso, foi realizada a aquisição do Centro de Pressão (COP) tanto na direção Ântero-Posterior (AP) quanto na Médio-Lateral (ML) em paralelo à aquisição bilateral do EMG dos músculos (SO, TA, GL e GM) nas três condições (antes, durante e após a vibração do tendão calcâneo). Para os estímulos de 1 e 2,5mm realizados a 80 Hz as diferenças foram significativas em relação a todas as variáveis quando comparadas nas três condições, com exceção apenas do DP do TA e GM e, do valor médio do COP ML a 1mm. Em relação à freqüência de 15 Hz, notou-se que não houve diferenças significativas tanto no COP AP e ML quanto no DP do EMG dos músculos da perna esquerda entre as três condições. Quanto aos dados referentes ao DP dos músculos analisados na perna direita, os resultados mostraram que não houve efeitos significativos tanto ao utilizar 15Hz como 80Hz em todas as três condições. Em geral, estes dados mostraram que durante um estímulo vibratório mais forte o COP deslocouse mais para a direção posterior e lateral esquerda do sujeito. E, após interromper o estímulo, em alguns casos o COP ainda mostrava uma alteração prolongada. Em relação à amplitude média do reflexo H, para as amplitudes de vibração de 1 e 2,5 mm a 15 e 80 Hz, as análises apontaram que durante a vibração houve uma forte redução na amplitude do reflexo, sendo que em alguns casos ainda permaneceram reduzidas na condição pós-vibratória. Os resultados mostram que a vibração aplicada ao tendão calcâneo pode ser um forte estímulo à medula e capaz de alterar o controle postural, dependendo de suas características, uma vez que, com parâmetros apropriados, induziu alterações imediatas nos resultados do reflexo H, do COP e do EMG (p.e.). Porém, as alterações a vibrações aplicadas de modo a ativar seletivamente as fibras aferentes do grupo Ia e II mostraram efeitos diferenciais. Vibrações a 80Hz de frequência e a 1 e 2,5mm foram as que mais causaram alterações. A significativa ação sobre o reflexo H é compatível com o aumento da frequência de disparos dos aferentes Ia. Entretanto a forte ação sobre o COP dessas vibrações a 80 Hz sugere que os aferentes Ia podem ter uma importância maior do que a literatura recente tem preconizado, pelo menos para correções a perturbações posturais, uma vez que pode-se supor que a 80 Hz e 1 mm de amplitude os aferentes tipo II são pouco ativados. Por outro lado, a vibração a 15 Hz teve um efeito signficativo sobre o reflexo H mas sem afetar o COP, o que sugere que esta frequência consegue ativar a via Ia, causando depressão homossináptica e/ou inibição pré-sináptica dos aferentes Ia, mas sem chegar a influir no COP de forma significativa. Os resultados são interessantes do ponto de vista de aplicações em potencial para áreas como fisioterapia e reabilitação de pessoas com alterações posturais na clínica. Adicionalmente, abrem novas questões quanto às interpretações fisiológicas de vibrações a diferentes freqüências sobre o tendão calcâneo. / A vibration applied to a muscle tendon increases the firing frequency of afferents of types Ia and II innervating muscle spindles, and hence affects the spinal cord circuits and this can affect motor control. The aim of this study was to analyze the effect of vibrations of two frequencies (15 and 80Hz) and two amplitudes (1 and 2.5 mm) applied to the right Achilles tendon on the standing posture and on the H reflex. The hypothesis was that the high frequency vibration activates preferentially the Ia axons while the 15 Hz vibration activates preferentially the type II axons and hence the 80 Hz vibration would have a strong effect on the H reflex and the 15 Hz vibration would have a strong effect on posture. Fourteen subjects participated in this study. Their H reflex was acquired in the upright position while their Achilles tendon was vibrated. After an interval of rest, the center of pressure (COP) signal was acquired for both the antero-posterior (AP) and the medio-lateral (ML) directions in parallel with the acquisition of bilateral electromyograms (EMG) (SO, TA, and GL GM) in the three conditions (before, during and after the vibration of the Achilles tendon). For 1 and 2.5 mm vibrations at 80 Hz the differences were significant for all variables compared in the three conditions, except for the standard deviation (SD) of the TA and GM EMGs and the average value of COP ML for 1mm vibration. For the 15 Hz vibration, there were no significant differences in both the AP and ML COP and SD of the EMG of the left leg in the three conditions. The results for the EMG SD of the right leg showed no significant effects when using both 15Hz and 80Hz in all three conditions. These data showed that during a stronger vibratory stimulus the COP shifted more to the posterior direction and the left side of the subject. And, after stopping the stimulus, in some cases, the COP had not returned to the initial position. In relation to the mean H reflex amplitude for 1 and 2.5 mm vibrations at 15 and 80 Hz, the analysis showed that during vibration there was a stronger reduction in the amplitude of the H reflex, and in some cases the amplitude remained reduced in the post-vibratory period. The results showed that the vibration applied to the Achilles tendon can be a powerful stimulus to the spinal cord and capable of altering the postural control. The effects depended on the vibration features, since, with appropriate parameters, it led to immediate changes in the results of the H reflex, the COP and left leg EMG. However, 80 Hz vibration (1 and 2.5 mm) was the one that caused the largest changes both on COP and H reflex amplitude. The significant action on the H reflex is consistent with the increased frequency of firing of Ia afferent. However the strong action on the COP of vibrations at 80 Hz suggests that the Ia afferents may have a greater importance than what the recent literature has suggested, at least for postural corrections to disturbances, since it can be assumed that the type II afferents are little activated at 80 Hz and 1 mm amplitude. Furthermore, vibration at 15 Hz had a significant effect on the H reflex without affecting the COP, suggesting that vibrations at this frequency can activate Ia afferents, causing homosynaptic depression and / or presynaptic inhibition of Ia afferents, but without influencing the COP significantly. The results are interesting from the standpoint of potential applications to areas such as physical therapy and rehabilitation of patients in the clinic. Additionally, they raise new questions about the physiological mechanisms behind vibratory stimuli applied at different frequencies on the Achilles tendon.

by Chan Suk Ping. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 105-119). / Abstract also in Chinese. / Acknowledgments --- p.i / Abstract --- p.ii / List of Tables --- p.ix / List of Figures --- p.xii / Abbreviation --- p.xiv / Chapter CHAPTER ONE --- INTRODUCTION / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- The Research Problem --- p.7 / Chapter 1.2.1 --- Purpose of The Study --- p.7 / Chapter 1.2.2 --- Variables and Definition of Terms --- p.8 / Chapter 1.2.3 --- Hypotheses --- p.10 / Chapter 1.2.4 --- Significance of The Study --- p.11 / Chapter CHAPTER TWO --- REVIEW OF LITERATURE / Chapter 2.1 --- Benefits and Potential Disadvantages of Stretching --- p.12 / Chapter 2.1.1 --- Benefits of Stretching --- p.12 / Chapter (a) --- Muscle Relaxation --- p.12 / Chapter (b) --- Performance Enhancement --- p.14 / Chapter (c) --- Prevention of Injury --- p.17 / Chapter (d) --- Increase of Range of Motion --- p.19 / Chapter (e) --- Prevention of Muscle Soreness --- p.20 / Chapter 2.1.2 --- The Potential Disadvantages of Stretching --- p.20 / Chapter 2.2 --- Limiting Factors of Flexibility --- p.22 / Chapter 2.2.1 --- Muscle --- p.22 / Chapter (a) --- Histologic Components of Muscle --- p.22 / Chapter (b) --- Muscular Elongation --- p.23 / Chapter (c) --- The Effects of Immobilization --- p.23 / Chapter 2.2.2 --- Connective Tissue --- p.24 / Chapter (a) --- Collagen --- p.25 / Chapter (b) --- Elastic Tissue --- p.27 / Chapter (c) --- Tissue Composed of Connective Tissue --- p.27 / Chapter 2.2.3 --- The Mechanical Properties of Soft Tissue --- p.30 / Chapter 2.2.4 --- "Age, Gender, Physical Activity and Temperature" --- p.33 / Chapter 2.3 --- Neurophysiology of Stretching --- p.34 / Chapter 2.3.1 --- Muscle Spindles and Golgi Tendon Organs --- p.34 / Chapter (a) --- Structure and Role of Muscle Spindle --- p.35 / Chapter (b) --- Structure and Role of Golgi Tendon Organs --- p.38 / Chapter (c) --- Parallel and Series End Organs --- p.38 / Chapter 2.3.2 --- Electromyography --- p.39 / Chapter 2.4 --- Hamstrings --- p.43 / Chapter 2.4.1 --- Functions of Hamstrings --- p.43 / Chapter 2.4.2 --- Limited Range of Motion in Hamstrings --- p.45 / Chapter 2.4.3 --- Measurement of Hamstrings Flexibility --- p.46 / Chapter 2.5 --- Stretching Protocol --- p.50 / Chapter 2.5.1 --- Modes of Stretching --- p.50 / Chapter 2.5.2 --- Intensity of Stretching --- p.53 / Chapter CHAPTER THREE --- METHOD / Chapter 3.1 --- Subjects --- p.55 / Chapter 3.2 --- Instrumentation --- p.57 / Chapter 3.3 --- Procedure --- p.60 / Chapter 3.4 --- Reliability Study --- p.69 / Chapter 3.5 --- Data Analysis --- p.70 / Chapter CHAPTER FOUR --- RESULTS / Chapter 4.1 --- Reliability Study --- p.72 / Chapter 4.2 --- Experimental Study --- p.73 / Chapter 4.2.1 --- Range of Motion of Pre-Test and Post-Test --- p.74 / Chapter 4.2.2 --- Passive Resistance of Pre-Test and Post-Test --- p.75 / Chapter 4.2.3 --- Subjective Rating of Pre-Test and Post-Test --- p.76 / Chapter 4.2.4 --- Myoelectric Activities of Hamstrings of Pre-Test and Post-Test --- p.76 / Chapter 4.2.5 --- Hamstrings Performance of Pre-Test and Post-Test --- p.79 / Chapter 4.2.6 --- Range of Motion Difference among Trained and Untrained Groups --- p.81 / Chapter 4.2.7 --- Passive Resistance of Hamstrings Difference among Trained and Untrained Groups --- p.82 / Chapter 4.2.8 --- Subjective Rating of Perceived Stretch Difference among Trained and Untrained Groups --- p.82 / Chapter 4.2.9 --- Myoelectric Activities of Hamstrings Difference among Trained and Untrained Groups --- p.83 / Chapter 4.3.0 --- Performance of Hamstrings Difference among Trained and Untrained Groups --- p.83 / Chapter CHAPTER FIVE --- DISCUSSION / Chapter 5.1 --- Hamstrings Flexibility Analysis --- p.92 / Chapter 5.2 --- Hamstrings Passive Resistance Analysis --- p.94 / Chapter 5.3 --- Rating of Perceived Stretch Analysis --- p.97 / Chapter 5.4 --- Hamstrings Myoelectric Activities Analysis --- p.98 / Chapter 5.5 --- Hamstrings Performance Analysis --- p.100 / Chapter 5.6 --- Limitations and Suggestions --- p.102 / Chapter 5.7 --- Conclusions --- p.103 / REFERENCES --- p.105 / APPENDIX / Appendix A. Informed Consent / Appendix B. Personal Particulars and Past Medical History Screening Sheet / Appendix C. Perceived Stretch Rating Scale / Appendix D. Record Sheet

Orientador: Ney Lemke / Resumo: O sono (do latim, somnus) é um período que apresenta uma atividade fisiológica característica, que pode ser registrada com o EEG. Algumas ondas em um sinal de EEG são vistas apenas durante o sono, como os fusos do sono e complexos K. O fuso é um dos elementos mais bem conhecidos no estudo do sono. No presente estudo serão estudados fusos globais e potenciais complexos K, os quais são observados simultaneamente em todos os canais de EEG. Para isto, um novo método de investigação foi proposto, que estuda tanto o envelope do sinal quanto a fase/frequência de cada fuso. Através da análise da fase do fuso global, foi mostrado que 90% dos fusos de indivíduos saudáveis sincronizam com um tempo de latência de 0,11s. O método também avalia a frequência de modulação (chirp) de fusos globais, e foi averiguado que não há correlação entre o chirp destes fusos e sua sincronização. Através do estudo do envelope do sinal juntamente com a implementação de um modelo de propagação isotrópico, foi possível estimar a origem do fuso e sua velocidade de propagação. Os resultados obtidos indicam que através desta abordagem simples e não invasiva é possível determinar, com uma precisão razoável, o local de origem dos fusos do sono, e sua velocidade estimada de propagação de 0,12m/s. Os potenciais complexos K detectados foram usados para avaliar a robustez do método desenvolvido, e apresentaram frequências, durações e amplitudes dentro das faixas esperadas para complexos K. A velocidade do propagação ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Sleep (derived from the Latim, somnus) is a brain state with distinct physiological activity that can be investigated by EEG evaluation. Some waves are unique in sleep EEG such as sleep spindles and K complexes. Spindles are one of the best known elements in sleep studies. In this work we considered global spindles and K complexes, which are spindles that are observed simultaneously in all EEG channels. We propose a method that investigates both the signal envelope and phase/frequency of each global spindle. By analysing the spindle phase we showed that 90% of spindles in healthy subjects synchronize with a median latency time of 0.11 s. The method also measured the frequency slope (chirp) of global spindles and found that global spindle chirp and synchronization are not correlated. By investigating the signal envelopes and implementing a homogeneous and isotropic propagation model, we could estimate both the signal origin and velocity in global spindles. Our results indicate that this simple and non-invasive approach could determine with reasonable precision the spindle origin, and allowed us to estimate a signal speed of 0.12 m/s.Potential K complexes are used to assess the robustness of developed method and shows that frequencies, durations and amplitudes within the K complex expected range. Propagation velocity in potential K complexes are around 0.05 m/s which is lower than spindles velocity. Partial synchronization tendencies were detected in potential K complex, a... (Complete abstract click electronic access below) / Doutor

O músculo estriado esquelético apresenta em sua constituição células satélites (CS) que se encontram em estado quiescente localizadas entre o sarcolema e a lâmina basal das fibras musculares. As CS podem ser ativadas, diferenciando em mioblastos, contribuindo para regeneração e/ou crescimento do tecido muscular. Os Fusos neuromusculares são mecanorreceptores localizados no interior dos músculos esqueléticos considerados a unidade contrátil reguladora, monitorando a velocidade e duração do alongamento do músculo. Está composto de fibras intrafusais (FIF), circundadas por uma bainha de tecido conjuntivo e encontra-se paralelo às fibras extrafusais. A desnervação promove alterações no músculo esquelético, tanto em CS, quanto nos fusos neuromusculares. Este trabalho analisou quantitativamente as FIF e a proliferação de CS em músculos esquelético de ratos desnervados por longo período. Foram utilizados ratos Wistar. Os animais foram divididos em grupos desnervados e controle. Os músculos Sóleo e Extensor longo dos dedos (EDL) foram desnervados experimentalmente. Após os períodos de 0, 12, 16, 19, 30 e 38 semanas, os músculos foram dissecados, removidos e preparados histológicamente. A porcentagem de CS em músculos imediatamente após desnervação aumenta em relação ao músculo normal e depois decresce em ambos os músculos. Durante o progresso do tempo de desnervação ocorreu um aumento no número de FIF, se comparado com o grupo normal. O número de CS diminui significantemente entre os períodos de desnervação, em ambos os grupos. Nos músculos estudados quanto menor a porcentagem de CS maior é o número de FIF e, aumentando o tempo de desnervação, diminui o número de CS. Em relação às FIF, no grupo controle com o aumento do tempo, o número de fibras não se altera. Já para o grupo experimental, com o aumento do tempo de desnervação, diminui o número de CS e aumenta o número de FIF significantemente. Concluimos então que nos músculos desnervados por longo período ocorre diminuição na porcentagem de células satélites e aumento no número de FIF. Finalmente nossos resultados sugerem que entre 16ª e 19ª semana pós-desnervação encontra-se o melhor período para reinervação de um músculo desnervados. / The skeletal muscle consists of satellite cells (SC) which are in a quiescent state located between the sarcolemma and basal lamina of the muscle fibers. The SC can get activated, differentiating into myoblasts, contributing to regeneration and/or growth of muscle tissue. The neuromuscular spindles are mechanoreceptors located within the skeletal muscle and are considered as contractile regulatory unit, monitoring the speed and duration of muscle stretching. It is composed of Intrafusal muscle fibers (FIF), surrounded by a sheath and is parallel to extrafusal fibers. Denervation cause changes in skeletal muscles both in the CS and neuromuscular spindles. This study analyzed quantitatively the FIF and the proliferation of CS in rat skeletal muscle, denervated for long period. We used Wistar rats to perform this study. The animals were divided into control and denervated groups. The soleus and extensor digitorum longus (EDL) were denervated experimentally. After periods of 0, 12, 16, 19, 30 and 38 weeks, the muscles were dissected, removed and were prepared for histological analysis. The percentage of SC in muscles immediately after denervation, increases in relation to normal muscle and later decreases in both the groups. During the process of denervation, there was an increase in FIF when compared with normal group. The number of SC reduces significantly between the periods of denervation in both the groups. In the muscles studied, the smaller the percentage of SC, higher is the number of FIF and increase in the duration of denervation, reduces the number of SC. As for FIF, with the increase in time in control group, the number of fibres was unaltered. However, in the experimental group, with increase in the time of denervation, the number of SC decreases while there is increase in the number of FIF significantly. We thus conclude that in denervated mucles for long period, there is decrease in the percentage of satellite cells and increase in FIF. Finally our results suggest that the period between 16th and 19th week of post denervation is the best time for reinnervation of denervated muscle.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg 2016 / The quantity and particle size distribution of pulverised coal supplied to combustion equipment downstream of coal pulverising plants are critical to achieving safe, reliable and efficient combustion. These two key performance indicators are largely dependent on the mechanical condition of the pulveriser. This study aimed to address the shortfalls associated with conventional time-based monitoring techniques by developing a comprehensive online pulveriser condition monitoring philosophy. A steady-state Mill Mass and Energy Balance (MMEB) model was developed from first principles for a commercial-scale coal pulveriser to predict the raw coal mass flow rate through the pulveriser. The MMEB model proved to be consistently accurate, predicting the coal mass flow rates to within 5 % of experimental data. The model proved to be dependent on several pulveriser process variables, some of which are not measured on a continuous basis. Therefore, the model can only function effectively on an industrial scale if it is supplemented with the necessary experiments to quantify unmeasured variables. Moreover, a Computational Fluid Dynamic (CFD) model based on the physical geometry of a coal pulveriser used in the power generation industry was developed to predict the static pressure drop across major internal components of the pulveriser as a function of the air flow through the pulveriser. Validation of the CFD model was assessed through the intensity of the correlation demonstrated between the experimentally determined and numerically calculated static pressure profiles. In this regard, an overall incongruity of less than 5 % was achieved. Candidate damage scenarios were simulated to assess the viability of employing the static pressure measurements as a means of detecting changes in mechanical pulveriser condition. Application of the validated pulveriser CFD model proved to be highly advantageous in identifying worn pulveriser components through statistical analysis of the static pressure drop measured across specific components, thereby demonstrating a significant benefit for industrial application. / MT2016

Submitted by Rafael Toledo Fernandes de Souza (rafael@ibb.unesp.br) on 2016-04-27T21:08:41Z No. of bitstreams: 1 TeseRafaelTFS.pdf: 24959368 bytes, checksum: f8cc766a544e297b446817f14d467e4e (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-04-29T22:14:03Z (GMT) No. of bitstreams: 1 souza_rtf_dr_bot.pdf: 24959368 bytes, checksum: f8cc766a544e297b446817f14d467e4e (MD5) / Made available in DSpace on 2016-04-29T22:14:03Z (GMT). No. of bitstreams: 1 souza_rtf_dr_bot.pdf: 24959368 bytes, checksum: f8cc766a544e297b446817f14d467e4e (MD5) Previous issue date: 2016-03-10 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O sono (do latim, somnus) é um período que apresenta uma atividade fisiológica característica, que pode ser registrada com o EEG. Algumas ondas em um sinal de EEG são vistas apenas durante o sono, como os fusos do sono e complexos K. O fuso é um dos elementos mais bem conhecidos no estudo do sono. No presente estudo serão estudados fusos globais e potenciais complexos K, os quais são observados simultaneamente em todos os canais de EEG. Para isto, um novo método de investigação foi proposto, que estuda tanto o envelope do sinal quanto a fase/frequência de cada fuso. Através da análise da fase do fuso global, foi mostrado que 90% dos fusos de indivíduos saudáveis sincronizam com um tempo de latência de 0,11s. O método também avalia a frequência de modulação (chirp) de fusos globais, e foi averiguado que não há correlação entre o chirp destes fusos e sua sincronização. Através do estudo do envelope do sinal juntamente com a implementação de um modelo de propagação isotrópico, foi possível estimar a origem do fuso e sua velocidade de propagação. Os resultados obtidos indicam que através desta abordagem simples e não invasiva é possível determinar, com uma precisão razoável, o local de origem dos fusos do sono, e sua velocidade estimada de propagação de 0,12m/s. Os potenciais complexos K detectados foram usados para avaliar a robustez do método desenvolvido, e apresentaram frequências, durações e amplitudes dentro das faixas esperadas para complexos K. A velocidade do propagação encontrada para os potenciais complexos K foi de 0,05m/s, menor do que a dos fusos do sono. Os potenciais complexos K mostraram ter uma tendência de sincronização parcial, propriedade esta descrita para os complexos K na literatura. O método desenvolvido também foi aplicado em indivíduos com Apneia Obstrutiva do Sono (AOS). A maioria dos parâmetros analisados não apresentaram diferenças significativas entre indivíduos saudáveis e com AOS; exceto que, em indivíduos com AOS, a duração da sincronização apresentou um valor 34,18% menor, e a posição de origem dos fusos apresentou dois focos diferentes. Desta maneira, conclui-se que o método desenvolvido foi aplicado com sucesso nos grafoelementos avaliados, pois consegue recuperar as informações esperadas, e pode ser útil como uma ferramenta diagnóstica não invasiva. / Sleep (derived from the Latim, somnus) is a brain state with distinct physiological activity that can be investigated by EEG evaluation. Some waves are unique in sleep EEG such as sleep spindles and K complexes. Spindles are one of the best known elements in sleep studies. In this work we considered global spindles and K complexes, which are spindles that are observed simultaneously in all EEG channels. We propose a method that investigates both the signal envelope and phase/frequency of each global spindle. By analysing the spindle phase we showed that 90% of spindles in healthy subjects synchronize with a median latency time of 0.11 s. The method also measured the frequency slope (chirp) of global spindles and found that global spindle chirp and synchronization are not correlated. By investigating the signal envelopes and implementing a homogeneous and isotropic propagation model, we could estimate both the signal origin and velocity in global spindles. Our results indicate that this simple and non-invasive approach could determine with reasonable precision the spindle origin, and allowed us to estimate a signal speed of 0.12 m/s. Potential K complexes are used to assess the robustness of developed method and shows that frequencies, durations and amplitudes within the K complex expected range. Propagation velocity in potential K complexes are around 0.05 m/s which is lower than spindles velocity. Partial synchronization tendencies were detected in potential K complex, a propriety described for K complex in the literature. Obstructive Sleep Apnea (OSA) subjects were also assessed by our method. The majority of analysed parameters do not present significant difference between healthy and OSA subjects except by synchronization duration (34.18% lower in OSA) and two distinct focal points in OSA spindle origin. The proposed methodology retrieved the expected results, obtained by EEG analysis and other more complex techniques and our results indicate that it can be used as a diagnosis tool and to explore other sleep phenomena, such as K complexes. / FAPESP: 2012/22413-2