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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
251

The Effect of Ptellofemoral Pain Syndrome on the Hip and Knee Neuromuscular Control on Dynamic Postural Control Task

Goto, Shiho 28 September 2009 (has links)
No description available.
252

Assessment of postural, locomotor, and physical fitness status in individuals with intellectual and developmental disabilities

Turner, Alana J 09 August 2022 (has links)
Introduction: Postural control and locomotion deficits can be observed during the early years of childhood development and throughout life. For those with disabilities, these deficits can advance past the development years and into adolescence and adulthood while affecting the quality of life and daily activity. Finding interactive rehabilitative activities to delay or limit these deficits is essential for people with disabilities to improve their quality of life, inclusion, and overall movement. Adapted physical activity/sports like badminton and virtual reality could promote improvements in postural and locomotor status for young adults with intellectual and developmental disabilities like cerebral palsy (CP), intellectual disability (ID), and autism spectrum disorder (ASD). Purpose: These studies aim to assess the postural and locator status of young adults with intellectual and developmental disabilities after participating in a 12-week badminton and intensive virtual reality programs. Methods: Study A will follow a multiple baseline approach to access postural control, locomotion, and areas of physical fitness in young adults with IDD utilizing the immersive virtual reality game Fruit Ninja™ while study B will follow and repeated measures design accessing static postural control for students in a comprehensive transition program for intellectual disabilities at a southeastern university.
253

Assessing the Effects of Exoskeleton Use on Balance and Postural Stability

Park, Jangho 30 September 2021 (has links)
There is emerging evidence for the potential of occupational back-support exoskeletons (BSEs) to reduce physical demands, and thereby help control/prevent the risk of overexertion injuries associated with manual material handling. However, it is important to understand whether BSEs also introduce any unintended safety challenges. One potential risk associated with BSE use is increased risk of falls, since their extra weight, rigid structure, and external hip extension torque may increase demands on the postural control system. However, there is currently limited evidence on whether, and to what extent, BSE use alters postural stability and/or fall risk. The primary goal of this work was to understand the effects of exoskeleton use, and quantify the effects of exoskeleton design parameters, on balance and postural stability, with a focus on passive BSEs used for repetitive lifting work. A comprehensive evaluation of BSE use was performed under controlled laboratory conditions, focusing on three classes of human activity that form the basis of maintaining postural balance in diverse real-life scenarios: maintenance of a specified posture, voluntary movement, and reaction to an external perturbation. The first study demonstrated that during quiet bipedal stance, BSE use increased median frequency and velocity of the center of pressure in the anterior-posterior direction. In the second study on level walking, BSE use caused an increase in gait step width and gait variability, and decrease in the margin of stability. BSE use with high supportive torque led to adapted gait patterns in early-stance phase. Hip range of motion and peak hip flexion velocity also decreased, and participants exhibited different strategies to increase mechanical energy for propelling the leg in late-stance phase: these effects increased with increasing torque applied by the exoskeleton. In the final study, BSE use did not alter the maximal lean angle from which individuals could successfully execute single step balance recovery, following a forward loss of balance. However, several recovery responses were negatively affected by BSE use, including increased reaction time, impeded hip flexion, and reduced margin of stability in the high-torque condition. This is the first systematical investigation to quantify the effects of passive BSEs with multiple supportive torque levels on balance and postural stability. While exoskeleton effects on static balance were minimal, more substantial changes in gait spatiotemporal parameters, hip joint kinematics, and dynamic margins of stability were observed in the later studies. Our results indicate that postural stability deteriorated with exoskeleton use in dynamic conditions, and provide mechanistic insight into how stability is altered by different exoskeleton design factors such as added mass, restricted range of motion, and external hip extension torque. While our results are suggestive of increased fall risk, especially in the high-torque condition, fall risk in real life is moderated by a complex combination of individual and environmental conditions. Future work should consider more complex, realistic tasks and also include a more diverse sample that is studied under longer exposure durations, to further elucidate these findings. Our characterizations of a wide variety of postural responses as a function of exoskeleton torque settings are expected to contribute to improving both design and practice guidelines to facilitate the safe adoption of BSEs in the workplace. / Doctor of Philosophy / Occupational back-support exoskeletons (BSEs) – wearable mechanical systems designed to support, augment, and/or assist back extension – are expected to serve as an alternative workplace intervention to control and prevent overexertion injuries related to manual material handling tasks. While recent studies have shown the beneficial effects of BSE use in terms of physical load reduction on the low back, some concerns have also been raised on unexpected or unintended effects of exoskeletons. One potential risk associated with exoskeleton use is increased risk of falls, since a BSE's extra weight, rigid structure, and external hip extension torque are expected to place increased demands on the postural control system. Increase in fall risk is a critical safety concern, as occupational falls are a serious problem in terms of injuries, medical/industrial cost, and lost work time. However, there exists limited evidence on whether the use of a BSE alters postural stability and/or increases fall risk. Hence, the goal of our study was to quantify the effects of BSE use on postural stability in various conditions related to real-life scenarios, such as standing balance, walking stability and how one would respond to a loss of balance following an external perturbation. Our results showed that during quiet standing, BSE use slightly increased postural sway. In level walking tasks, BSE use had adverse effects on step length, step width, and dynamic stability. Furthermore, wearing a BSE with high supportive torque led to adapted gait patterns in early-stance phase, whereas participants showed different strategies to increase mechanical energy for propelling the leg in late-stance phase. In the final study investigating single step balance recovery following a forward loss of balance, we found that BSE use negatively affects balance recovery, mainly by impeding hip flexion. Thus, our work suggests that exoskeleton use can deteriorate balance and/or postural stability in situations of static standing, voluntary walking, and reacting to an external perturbation, thereby potentially leading to an increase in fall risk. These effects may be more pronounced among specific population sub-groups such as older workers, and may also affect individuals more severely under conditions of stress or fatigue. Hence, future studies must include more rigorous testing of BSE use using a variety of challenging and realistic scenarios, and also include more diverse population samples. The findings from this work are expected to contribute to improving design and practice guidelines to facilitate the safe adoption of BSEs in the workplace.
254

Impact des troubles musculosquelettiques sur les mécanismes du contrôle postural chez les adolescents-hockeyeurs de niveau élite et intervention en Reconstruction Posturale®

Pilon, Francine 07 1900 (has links)
Les adolescents-hockeyeurs peuvent être affligés de troubles musculosquelettiques (TMS) résultant d’un excès de tension musculaire lequel peut mener à des déformations ou déséquilibres musculaires ainsi qu’à une attitude posturale inadéquate. Les conséquences de ces changements mènent souvent à une surcharge inutile du système musculosquelettique (SMS), à la perturbation des mécanismes du contrôle postural et éventuellement à l’apparition de douleurs musculaires et articulaires. Les interventions qui s’attaquent aux TMS par une rééquilibration de la tension musculaire sont peu nombreuses. Les interventions qui s’attaquent aux TMS par une normalisation de la tension musculaire sont peu nombreuses. La Reconstruction Posturale® (RP), testée cliniquement, est l’une d’entre elles. Dans un premier temps, cette thèse visait à identifier les caractéristiques du contrôle postural chez les adolescents-hockeyeurs de niveau élite lorsque le système somatosensoriel est mis à l’épreuve en position debout quasi statique pieds nus et en patins. Dans un deuxième temps, nous avons évalué l’impact d’une intervention en RP sur des variables cliniques et biomécaniques, chez ces athlètes qui souffrent de TMS. Soixante-sept adolescents-hockeyeurs de niveau élite âgés de 15 à 18 ans ont participé à l’étude. Le contrôle postural de cinquante-sept joueurs a été évalué en position debout sur deux plateformes de force les yeux ouverts et les yeux fermés, pieds nus sur une surface dure et sur une mousse. De ce groupe, trente-cinq sujets ont également été évalués en patins, les yeux ouverts et les yeux fermés. Par la suite, neuf adolescents-hockeyeurs souffrant de TMS, ont été sélectionnés pour participer au protocole d’intervention thérapeutique en RP qui consistait en l’application de six séances de thérapie prodiguées sur une période de six semaines. Le déplacement du centre de pression (CP) sous les pieds a été calculé dans les directions antéro-postérieure (AP) et médio-latérale (ML). La vélocité moyenne du CP, le déplacement moyen du CP et l’étendue du CP ont été retenus pour rendre compte de la performance du contrôle posturale. D’autre part, l’asymétrie de mise en charge, la trajectoire du CP sous les pieds gauche et droit, le CPc pour rendre compte de la stratégie de chevilles et le CPv pour rendre compte de la stratégie de hanches ont été retenues pour identifier les stratégies utilisées pour maintenir l’équilibre. L’impact de l’intervention en RP a été évalué à l’aide de trois variables cliniques soit la douleur à l’aide de l’échelle visuelle analogue (ÉVA), la capacité fonctionnelle à l’aide d’un un questionnaire autoadministré et des photographies de la posture debout pour rendre compte des variables posturales biomécaniques. Nos résultats montrent que chez les adolescents-hockeyeurs la performance du contrôle postural en position debout statique est davantage perturbée par les changements somatosensoriels en direction ML alors qu’en AP, la perte d’informations visuelles ainsi que des changements somatosensoriels affectent la performance. Dans toutes les conditions expérimentales et dans les deux directions, nous avons observé une vélocité du CP remarquablement élevée, variant entre 18 et 22 mm/s. Au niveau des stratégies et indépendamment de la condition expérimentale, nous avons observé une dominance presque complète de la stratégie de cheville en AP alors qu’en ML, la stratégie de hanche dominait avec une contribution de la stratégie de cheville de plus de 20 %. En patins, en direction ML, aucun changement significatif de la performance n’a été observé. Toutefois en AP, nous avons observé une augmentation significative de la vélocité du CP, yeux ouverts et yeux fermés ainsi qu’une augmentation significative de l’étendue, yeux ouverts seulement. Au niveau des stratégies, la stratégie de cheville domine en AP et la stratégie de hanche domine en ML avec une contribution plus modeste de la stratégie de cheville qui était inférieure à 12 %. Chez les adolescents-hockeyeurs souffrant de TMS, post-intervention, nos résultats indiquent une diminution significative de la douleur et une amélioration des capacités fonctionnelles ainsi que de l’attitude posturale. Pré intervention en direction ML, nous avons observé une contribution significativement plus élevée de la stratégie de cheville au contrôle du CPnet et un retour vers des valeurs normales post-intervention. L’impact de l’intervention thérapeutique sur la performance du contrôle postural s’est avéré non significatif en ML et en AP. / Adolescent hockey players can suffer from musculoskeletal disorders (MSD) resulting from excess muscle tension that can lead to dysmorphisms, muscle imbalances as well as inadequate standing posture. The consequences of these changes often lead to unnecessary overload of the musculoskeletal system (MSS), disturbances in postural control mechanisms and eventually the development of muscular and joint pain. Very few interventions are design to address MSD by rebalancing muscle tension. One of the clinically tested interventions is Postural Reconstruction® (PR). Our first objective was to identify the characteristics of postural control among a population of elite adolescent-hockey players when the somatosensory system is disturbed while standing in a quasi static position barefoot and on skates. Secondly, we assessed the impact of an intervention in PR on various clinical and biomechanical variables among a population of elite adolescent hockey players suffering from MSD. Sixty seven elite adolescent hockey players, 15 to 18 years of age participated in the study. The postural control of fifty seven players was assessed in standing using two force platforms, in eyes open (EO) and eyes closed (EC) conditions barefoot on hard surface and on foam. From that group, thirty five players were also assessed on skates, EO and EC. Then, nine players suffering from MSD were selected to participate in the intervention protocol in RP consisting in the application of six therapeutic sessions held once a week for six consecutive weeks. Center of pressure (COP) movements under the feet was calculated in the antero-posterior (AP) and medio-lateral (ML) directions. To account for the performance of the postural control system, mean COP velocity and displacements as well COP range were used. The variables retained to account for the strategies used to maintain balance in the upright position were weight baring asymmetry, concordance of the COP trajectory as well as COPc for the contribution of the ankle strategy and COPv for the contribution of the hip strategy. Finally, the impact of PR intervention was assessed on pain level, functional capacity and postural biomechanical variables. Our results show that among elite adolescent hockey players, the performance of the postural control in standing in a quasi static position is more disturbed by changes somatosensory information in ML direction while in AP, the absence of visual information as well as changes in somatosensory information significantly affect the performance. In all experimental conditions, and in both directions, we observed a remarkably high mean velocity, ranging between 18 to 22 mm/sec. As for the strategies, independent of the experimental condition, we observed total dominance of the ankle strategy in AP while in ML, the hip strategy dominated with a 25 % contribution for the ankle strategy. On skates, in ML direction, no significant changes were observed in the performance. However, in AP, we observed a significant increase in the mean COP velocity, EO and EC, and significant increase in COP range, EO only. As for the strategies, we observed the same dominance but the contribution on the ankle strategy in ML was more modest, that is less than 12 %. For players suffering from MSD, our results show that six sessions of PR significantly improved the level of pain, functional capacity and body alignment in standing. Pre intervention in ML, we observed a significantly higher contribution of the ankle strategy to the control of the COPnet and post-intervention, a return to normal values. The impact of the PR intervention on postural control performance was not significant in ML and AP. In conclusion, our results show that in the early stage, a PR intervention has a greater impact on postural control stratégies rather than performance.
255

Posturální stabilizace a rovnováha - teoretická východiska problematiky a vymezení pojmů ( rešeršní práce ) / Postural stabilization and balance - theoretical background and definitions (literature review)

Uhlíková, Jana January 2016 (has links)
Title: Postural stabilization and balance - theoretical background and definitions (literature review) Objectives: The aim of this theses is to investigate the present situation of theoretical background of postural stabilization and balance and find out the differences between both of these phenomenons. The theses should summarize the current literature including the newest studies. Furthermore, it discusses the most used computerized measurements methods for assessing balance and postural control. Methods: The theses has character of literature review. It is divided into several parts. The beginning introduces the theoretical background. The descriptive and analytical chapter discuss the most used computerized measurement methods for assessing balance and postural control. The discussion summarizes the current situation and results of the theses. Results: The total amount of the 104 studies was found, but only 12 of them met the criteria of the theses. Currently the most used methods for assessing balance and postural control are the computerized dynamic posturography and the visual feedback posturography. In the published studies there were found several differences in the methods of posturography. Even, there was revealed ideological diversity in the authors' opinions and disunity in...
256

Interactions visuo-proprioceptives dans les pathologies dégénératives du rachis cervical relevant d'un traitement chirurgical / Visuo-proprioceptive interactions in degenerative cervical spine diseases requiring surgery

Freppel, Sébastien 12 December 2013 (has links)
La proprioception cervicale joue un rôle important dans le contrôle postural, mais la nature exacte de sa contribution est controversée. Dans certains cas de « coup du lapin », une atteinte posturale a été démontrée, sans que l'atteinte du rachis cervical puisse être tenue pour seule responsable. Malgré la forte prévalence des pathologies cervicales dégénératives, leurs conséquences posturales ont été peu étudiées dans la littérature scientifique. Il n'existe aucune publication centrée sur les deux types de pathologie responsables de névralgies cervicobrachiales : les hernies discales cervicales et l'arthrose cervicale. Cette étude a eu pour but d'évaluer le contrôle postural de deux groupes de patients présentant une pathologie cervicale dégénérative avec et sans stimulation optocinétique avant et après traitement chirurgical. Dix-sept patients présentant une radiculalgie ont été inclus dans cette étude et répartis en deux groupes selon l'origine arthrosique ou discale de la compression neurologique. Tous les patients ainsi que 31 témoins ont été soumis à un examen de posturographie statique comprenant 12 enregistrements : les quatre premiers enregistrements ont été réalisés la tête dans l'axe (à 0°) : yeux fermés, yeux ouverts sans stimulation optocinétique, yeux ouverts avec stimulation optocinétique dans le sens horaire, puis antihoraire. Ces quatre situations sensorielles ont été répétées tête tournée 30° à gauche, puis 30° à droite. Les patients ont à nouveau été soumis à ces 12 enregistrements six semaines après l'intervention. Aucun patient ne s'est plaint de sensations vertigineuses que ce soit en pré ou en postopératoire. Avant intervention, les yeux fermés, le groupe hernie discale était plus stable que le groupe arthrose. Après intervention, la contribution visuelle au contrôle postural avait diminué dans les deux groupes dans un environnement visuel dynamique, alors que dans un environnement visuel stable, elle n'avait diminué que dans le groupe arthrose. L'importance relative des informations visuelles et proprioceptives pour le contrôle postural varie selon le type de pathologie et la chirurgie tend à réduire la contribution visuelle surtout pour les patients présentant une arthrose cervicale / Cervical proprioception plays a key role in postural control, but its specific contribution is controversial. Postural impairment was shown in whiplash injuries without demonstrating the sole involvement of the cervical spine. The consequences of degenerative cervical spine diseases are underreported in posture-related scientific literature in spite of their high prevalence. No report has focused on the two different mechanisms underlying cervicobrachial pain: herniated discs and spondylosis. This study aimed to evaluate postural control of two groups of patients with degenerative cervical spine diseases with or without optokinetic stimulation before and after surgical treatment. Seventeen patients with radiculopathy were recruited and divided into two groups according to the spondylotic or discal origin of the nerve compression. All patients and a control population of 31 healthy individuals underwent a static posturographic test with 12 recordings; the first four recordings with the head in 0° position: eyes closed, eyes open without optokinetic stimulation, with clockwise and counter clockwise optokinetic stimulations. These four sensorial situations were repeated with the head rotated 30° to the left and to the right. Patients repeated these 12 recordings 6 weeks postoperatively. None of the patients reported vertigo or balance disorders before or after surgery. Prior to surgery, in the eyes closed condition, the herniated disc group was more stable than the spondylosis group. After surgery, the contribution of visual input to postural control in a dynamic visual environment was reduced in both cervical spine diseases whereas in a stable visual environment visual contribution was reduced only in the spondylosis group. The relative importance of visual and proprioceptive inputs to postural control varies according to the type of pathology and surgery tends to reduce visual contribution mostly in the spondylosis group
257

Conséquences de contractions musculaires volontaires et électro-induites exhaustives sur le contrôle postural bipodal et la fatigue centrale / Consequences of voluntary and stimulated fatiguing muscular contractions on bipedal postural control and central fatique

Felipe Fernandez, Emma 12 December 2011 (has links)
L’objectif général de ce travail doctoral était de comparer les effets de la fatigue musculaire des quadriceps femoris après un exercice musculaire volontaire (VOL) et un exercice musculaire électroinduit (ES) sur le contrôle postural bipodal, ainsi que sur la fatigue centrale. Les résultats montrent qu’à l’issue d’une tâche fatigante unilatérale ou bilatérale, l’exercice ES dégrade davantage la force usculaire que l’exercice VOL. Cependant, le contrôle postural bipodal est indifféremment perturbépar les deux exercices. En outre, les vitesses de récupération des capacités posturales et de force musculaire ne diffèrent pas à l’issue des exercices. Par ailleurs, l'exercice VOL altère davantage la commande centrale que l'exercice ES (immédiatement à l’issue de l’effort), tandis que celui-ci retarde l’apparition de la fatigue centrale et la maintient plus longuement. Etant donné que l'exercice VOL estinduit par la commande centrale et que l'exercice ES est généré par une stimulation artificielle externe, on peut émettre l’hypothèse que l'exercice VOL produit essentiellement une fatigue supraspinale, tandis que l'exercice ES engendre surtout une fatigue spinale. / The overall objective of this thesis was to compare the effect of fatigue of the quadriceps femoris after fatiguing voluntary contractions (VOL) and fatiguing neuromuscular electrical stimulation (ES) on bipedal postural control, and central fatigue. The results show that after unilateral or bilateral muscle fatigue, the ES exercise affected the muscle strength more than the VOL exercise. However, bipedal postural control was similarly deteriorated for both exercises. Moreover, the recovery speeds of postural control and muscle strength abilities did not differ for the both exercises. In addition, the VOL exercise alters central drive quicker than the ES exercise immediately after their completion while the ES exercise delays and prolongs the central fatigue. As the VOL exercise is induced by central command and the ES exercise is generated by artificial external stimulation, one can hypothesize that the VOL exercise especially produces supraspinal fatigue, while the ES exercise especially engenders spinal fatigue.
258

Efeitos da atividade física no controle postural e capacidade funcional de idosos

Lopes, Andrei Guilherme [UNESP] 27 October 2010 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:30:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-10-27Bitstream added on 2014-06-13T20:00:59Z : No. of bitstreams: 1 lopes_ag_dr_rcla.pdf: 2903807 bytes, checksum: 228b34baf835343d3246b38b7c81d87c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O envelhecimento, associado ao sedentarismo vem acompanhado de muitas alterações estruturais, funcionais e comportamentais. O controle postural depende da integridade dos sistemas sensoriais e motor e, portanto, as deteriorações que ocorrem nestes sistemas com a ausência de um estilo de vida saudável, podem influenciar o desempenho de controle postural. Entretanto, ainda não estão claras quais alterações funcionais nos sistemas sensoriais e motor podem ser promovidas pela pratica de exercícios físicos, bem como a relação entre estas alterações e as mudanças no desempenho de controle postural de adultos idosos. Assim, o objetivo deste estudo foi examinar os efeitos de um programa de atividade física no controle postural e componentes de capacidade funcional de idosos, abordando aspectos sensoriais, motores e o relacionamento entre ambos. Treze adultos idosos com idade entre 60 e 70 anos foram submetidos a avaliações sensoriais, motoras, de controle postural e capacidade funcional antes e após a participação em um programa de exercícios físicos generalizado. As avaliações sensoriais foram compostas por avaliação visual (acuidade e sensibilidade ao contraste) e somatossensorial (sensibilidade cutânea e sensibilidade ao movimento passivo). As avaliações motoras consistiram de medidas de torque articular e de latência de ativação muscular após perturbação da superfície de suporte. As avaliações de controle postural consistiram de medidas de oscilação corporal durante manutenção da postura ereta (em semitandem stance) e para capacidade funcional foi aplicada a bateria da AAHPERD, Os resultados indicaram que o programa de exercícios proposto influenciou positivamente as capacidades de agilidade, força e capacidade aeróbia e, ainda, a capacidade de produzir torque e latência muscular. Estes resultados indicam que o aumento causado na força muscular... / Aging and a sedentary life style exhibit several structural, functional and behavioral changes. A good postural control performance depends on the integrity of the sensory and motor systems, deterioration of these systems occurring with aging could influence the postural control performance, specifically in older adults that are more susceptible to falls. However, it is still unclear which sensory and motor functional changes can be affected by a physical fitness program, neither the relationship between these changes and the changes of the performance of postural control in older adults. Therefore, the purpose of this study was to examine the effects of a exercise training program in the performance of the sensory and motor systems and postural control in older adults and to investigate the relationship between changes in these systems and postural control in this population. Thirteen older adults with age from 60 to 70 years old were submitted to sensory, motor and postural control assessments. Sensory assessments were composed of visual (acuity and contrast sensitivity) and somatosensory assessments (tactile sensitivity of and sensitivity to passive motion). Motor assessments consisted of measurements of joint torque and muscular activity latency after displacement of support surface. Postural control assessments consisted of measuring the body oscillation during maintenance of the upright stance (semi-tandem stance) and de functional capacity where measured by the Functional fitness tests of AAHPERD. The results indicated that the training program improved de agility, strength and aerobic capacity of the functional capacity, the torque capacity and a reduction of the muscular latency. The absence of training effects on the postural control can indicate that the processing of sensory information can be more weight on de stand stance than the physical capabilities. The present study shows...(Complete abstract click electronic access below)
259

Influence de la fatigue sur le contrôle postural : spécificités des effets d’une fatigue musculaire volontaire ou électro-induite et impact d’une fatigue mentale occasionnée par une tâche cognitive prolongée. / Influence of fatigue on postural control : specificities of the effects of voluntary or electro-induced muscle fatigue and impact of mental fatigue caused by prolonged cognitive task.

Hachard, Betty 05 September 2019 (has links)
L’objectif général de ce travail doctoral était d’étudier les effets de la fatigue (physique et mentale) sur le contrôle postural. Tout d’abord, les effets de la fatigue musculaire du quadriceps fémoral induite par des contractions volontaires et des contractions électro-induites ont été comparés. Les résultats ont montré que des contractions volontaires altéraient davantage le contrôle postural que des contractions électro-induites pour une perte de force musculaire équivalente. Ceci s’expliquerait par la présence d’une fatigue centrale après les contractions volontaires, ainsi qu’une sollicitation différente des fibres musculaires entre les deux modalités de contraction. Des mécanismes compensatoires seraient mis en œuvre après ces deux modalités de contractions fatigantes, mais de façon plus prononcée pour les contractions volontaires. Concernant la fatigue mentale, les effets d’une tâche cognitive exigeante et prolongée sur ordinateur (induisant un état de fatigue mentale) et d’un visionnage de documentaire (tâche contrôle) sur le contrôle postural ont été comparés. De prime abord, la fatigue mentale affecterait le contrôle postural en condition de privation visuelle, en réduisant l’efficacité des stratégies d’attention associatives. De façon surprenante, visionner un documentaire conduirait également à une altération du contrôle postural, potentiellement en raison du maintien prolongé d’une posture assise affaissée. La posture assise pourrait ainsi constituer un facteur confondant dans les protocoles expérimentaux comportant une évaluation posturale. Une analyse statistique de classification en cluster hiérarchique a permis de mettre en évidence des sensibilités différentes au sein des individus à l’égard de la tâche mentalement fatigante. Le niveau de fatigue mentale serait associé au niveau de dégradation du contrôle postural sur un support stable avec les yeux ouverts. La réalisation d’une tâche cognitive prolongée exigeant une attention visuelle soutenue face à un écran d’ordinateur provoquerait une fatigue visuelle. Cette fatigue visuelle affecterait différemment les individus. Elle toucherait plus particulièrement les sujets les plus dépendants des informations visuelles, pour lesquels le contrôle postural se dégraderait davantage que les autres individus. / The overall objective of this doctoral work was to study the effects of fatigue (physical and mental) on postural control. First, the effects of femoral quadriceps muscle fatigue induced by voluntary contractions and electro-induced contractions were compared. The results showed that voluntary contractions affected postural control more than electro-induced contractions for an equivalent loss of muscle strength. This could be explained by the presence of central fatigue after voluntary contractions, as well as a different strain on muscle fibres between the two modes of contraction. Compensatory mechanisms would be implemented after these two modes of tiresome contractions, but more pronounced for voluntary contractions. With regard to mental fatigue, the effects of demanding and prolonged cognitive computer work (inducing mental fatigue) and documentary viewing (task control) on postural control were compared. At first glance, mental fatigue would affect postural control in conditions of visual deprivation, reducing the effectiveness of associative attention strategies. Surprisingly, viewing a documentary would also lead to an alteration in postural control, potentially due to the prolonged maintenance of a collapsed sitting posture. Sitting posture could thus be a confounding factor in experimental protocols involving postural evaluation. A statistical analysis of hierarchical cluster classification revealed different sensitivities within individuals towards the mentally demanding task. The level of mental fatigue would be associated with the level of degradation of postural control on a stable support with eyes open. Performing a prolonged cognitive task requiring sustained visual attention to a computer screen would cause visual fatigue. This visual fatigue would affect individuals differently. It would particularly affect the subjects most dependent on visual information, for which postural control would be more degraded than other individuals.
260

Étude des qualités psychométriques du Mini-BESTest avec la clientèle lésée médullaire en réadaptation

Roy, Audrey 09 1900 (has links)
No description available.

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