904 resultados para Fatigue musculaire


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Background: Chronic fatigue syndrome, also known as myalgic encephalomyelitis (CFS/ME), is characterized by chronic disabling fatigue and other symptoms, which are not explained by an alternative diagnosis. Previous trials have suggested that graded exercise therapy (GET) is an effective and safe treatment. GET itself is therapist-intensive with limited availability. Objective: While guided self-help based on cognitive behavior therapy appears helpful to patients, Guided graded Exercise Self-help (GES) is yet to be tested. Methods: This pragmatic randomized controlled trial is set within 2 specialist CFS/ME services in the South of England. Adults attending secondary care clinics with National Institute for Health and Clinical Excellence (NICE)-defined CFS/ME (N=218) will be randomly allocated to specialist medical care (SMC) or SMC plus GES while on a waiting list for therapist-delivered rehabilitation. GES will consist of a structured booklet describing a 6-step graded exercise program, supported by up to 4 face-to-face/telephone/Skype™ consultations with a GES-trained physiotherapist (no more than 90 minutes in total) over 8 weeks. The primary outcomes at 12-weeks after randomization will be physical function (SF-36 physical functioning subscale) and fatigue (Chalder Fatigue Questionnaire). Secondary outcomes will include healthcare costs, adverse outcomes, and self-rated global impression change scores. We will follow up all participants until 1 year after randomization. We will also undertake qualitative interviews of a sample of participants who received GES, looking at perceptions and experiences of those who improved and worsened. Results: The project was funded in 2011 and enrolment was completed in December 2014, with follow-up completed in March 2016. Data analysis is currently underway and the first results are expected to be submitted soon. Conclusions: This study will indicate whether adding GES to SMC will benefit patients who often spend many months waiting for rehabilitative therapy with little or no improvement being made during that time. The study will indicate whether this type of guided self-management is cost-effective and safe. If this trial shows GES to be acceptable, safe, and comparatively effective, the GES booklet could be made available on the Internet as a practitioner and therapist resource for clinics to recommend, with the caveat that patients also be supported with guidance from a trained physiotherapist. The pragmatic approach in this trial means that GES findings will be generalizable to usual National Health Service (NHS) practice.

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The correspondence in the Spanish-English translation is analyzed of three different fields of technical metaphors based upon blindness, fatigue, and the spiritual world. Some terms have been left aside that under the appearance of metaphors were mere samples of no-deviated language or cases of homonymy. The study reveals a higher presence of the metaphor in the Spanish language in the three fields of study, although the English language also shows a high index of metaphors. In between metaphors and non-metaphors, we find a lack of metaphorical equilibrium between Spanish and English in certain cases, which is a sign of the different perception of the reality. Finally, the conclusions shed light on the meaning of these words: blind, annoyance, fatigue, antifading, core, angels, espectrum, phantom, ghost, magic, postmortem, dead, etc.

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Nano-scale touch screen thin film have not been thoroughly investigated in terms of dynamic impact analysis under various strain rates. This research is focused on two different thin films, Zinc Oxide (ZnO) film and Indium Tin Oxide (ITO) film, deposited on Polyethylene Terephthalate (PET) substrate for the standard touch screen panels. Dynamic Mechanical Analysis (DMA) was performed on the ZnO film coated PET substrates. Nano-impact (fatigue) testing was performed on ITO film coated PET substrates. Other analysis includes hardness and the elastic modulus measurements, atomic force microscopy (AFM), Fourier Transform Infrared Spectroscopy (FTIR) and the Scanning Electron Microscopy (SEM) of the film surface.
Ten delta of DMA is described as the ratio of loss modulus (viscous properties) and storage modulus (elastic properties) of the material and its peak against time identifies the glass transition temperature (Tg). Thus, in essence the Tg recognizes changes from glassy to rubber state of the material and for our sample ZnO film, Tg was found as 388.3 K. The DMA results also showed that the Ten delta curve for Tg increases monotonically in the viscoelastic state (before Tg) and decreases sharply in the rubber state (after Tg) until recrystallization of ZnO takes place. This led to an interpretation that enhanced ductility can be achieved by negating the strength of the material.
For the nano-impact testing using the ITO coated PET, the damage started with the crack initiation and propagation. The interpretation of the nano-impact results depended on the characteristics of the loading history. Under the nano-impact loading, the surface structure of ITO film suffered from several forms of failure damages that range from deformation to catastrophic failures. It is concluded that in such type of application, the films should have low residual stress to prevent deformation, good adhesive strength, durable and good resistance to wear.

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Fatigue two months after myocardial infarction may indicate risk for persistent fatigue

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A research project entitled "Residual Stresses and Fatigue Behavior of Welded Structural Members" was conducted at the Structural Research Laboratory of the Engineering Research Institute at Iowa State University under the sponsorship of the Iowa State Highway Commission. The objective of the project was to study experimentally the fatigue behavior of flange plates in welded beam sections as influenced by different residual stress distributions which are caused by different sizes of welds.

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Several studies have found that fatigue is one of the most commonly reported symptoms after stroke and the most difficult to cope with. The present study aimed to investigate the presence and severity of self-reported fatigue six years after stroke onset and associated factors. The cohort "Life After Stroke Phase I" (n = 349 persons) was invited at six years to report fatigue (Fatigue Severity Scale 7-item version), perceived impact of stroke and global recovery after stroke (Stroke Impact Scale), anxiety and depression (Hospital Anxiety and Depression Scale), life satisfaction (Life Satisfaction Checklist) and participation in everyday social activities (Frenchay Activities Index). At six years 37% of the 102 participants in this cross-sectional study reported fatigue. The results showed that in nearly all SIS domains the odds for post-stroke fatigue were higher in persons with a higher perceived impact. Furthermore, the odds for post-stroke fatigue were higher in those who had experienced a moderate/severe stroke and had signs of depression and anxiety. Fatigue is still present in one-third of persons as long as six years after stroke onset and is perceived to hinder many aspects of functioning in everyday life. There is an urgent need to develop and evaluate interventions to reduce fatigue.

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The aim of this study was to investigate whether rinsing the mouth with a carbohydrate solution could improve skill-specific fencing performance and cognitive function following a fatigue inducing simulated bout of fencing in epee fencers. Eleven healthy, competitive epee fencers (three female; eight male; 33.9 ± 14.7 years; body mass 79 ± 16 kg; height 162 ± 54 cm) volunteered to participant in a single-blind crossover design study. During visit 1 participants completed a 1-minute lunge test and stroop test pre and post fatigue inducing fencing protocol. A 30 second electroencephalography (EEG) recording was taken pre-protocol participants were instructed stay in a seated stationary position with their eyes closed. Heart rate and ratings of perceived exertion were recorded following each fight during the fatiguing protocol. Participants mouth rinsed (10 seconds) either 25ml of a 6.7% maltodextrin solution (CHO) or 25ml of water (placebo) between fights and during the EEG recording. Blood lactate and glucose measurements were taken at baseline, pre and post protocol. All measurements and tests were repeated during a 2nd visit to the laboratory, except participants were given a different solution to mouth rinse, separated by a minimum of 5 days. The results showed an increase in heart rate (P < 0.05) and overall RPE (P < 0.001) over time in both trials. There were no recorded differences in blood glucose (F(1,8) = 0.634, P = 0.4, ηp 0.07) or blood lactate levels (F(1,8) = 0.123, P = 0.7, ηp 0.01) between trials. There was a significant improvement in lunge test accuracy in the CHO trial (F(1,8) = 5.214, P = 0.05, ηp 0.40). However, there was no recorded difference in response time to congruent (F(1,8) = 0.326, P = 0.58, ηp 0.04) or incongruent (F(1,8) = 0.189, P = 0.68, ηp 0.02) stimuli between trials. In conclusion mouth rinsing a CHO solution significantly improves accuracy of skill-specific fencing performance but does not affect cognitive function following a fatigue inducing fencing protocol in epee fencers.

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This study investigated the impact that mouth rinsing carbohydrate solution has on skill-specific performance and reaction time following a fatigue inducing bout of fencing in epee fencers. Nine healthy, national level epee fencers visited a laboratory on 2 occasions, separated by a minimum of 5 days, to complete a 1-minute lunge test and Stroop test pre and post fatigue. Heart rate and ratings of perceived exertion (RPE) were recorded during completion of the fatiguing protocol. Between fights the participants mouth rinsed for 10 seconds, either 25ml of 6.7% maltodextrin solution (MALT) or water (PLAC). Blood lactate and glucose were recorded at baseline, pre- and post-testing. Results showed an increase in heart rate and overall RPE over time in both conditions. There were no differences in blood glucose (F(1,8)=.63, P=.4, ηp=.07) or blood lactate levels (F(1,8)=.12, P=.70, ηp=.01) between conditions as a function of time. There was a significant improvement in lunge test accuracy during the MALT trial (F(1,8)=5.21, P=.05, ηp=.40) with an increase from pre (81.2 ±8.3%) to post (87.6 ±9.4%), whereas there was no significant change during the placebo (pre 82.1 ±8.8%, post 78.8 ±6.4%). There were no recorded differences between conditions in response time to congruent (F(1,8)=.33, P=.58, ηp=.04) or incongruent stimuli (F(1,8)=.19, P=.68, ηp=.02). The study indicates that when fatigued mouth rinsing MALT significantly improves accuracy of skill-specific fencing performance but no corresponding influence on reaction time was observed.

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The V˙O2 slow component (V˙O2sc) that develops during high-intensity aerobic exercise is thought to be strongly associated with locomotor muscle fatigue. We sought to experimentally test this hypothesis by pre-fatiguing the locomotor muscles used during subsequent high-intensity cycling exercise. Over two separate visits, eight healthy male participants were asked to either perform a non-metabolically stressful 100 intermittent drop-jumps protocol (pre-fatigue condition) or rest for 33 min (control condition) according to a random and counterbalanced order. Locomotor muscle fatigue was quantified with 6-s maximal sprints at a fixed pedaling cadence of 90 rev·min−1. Oxygen kinetics and other responses (heart rate, capillary blood lactate concentration and rating of perceived exertion, RPE) were measured during two subsequent bouts of 6 min cycling exercise at 50% of the delta between the lactate threshold and V˙O2max determined during a preliminary incremental exercise test. All tests were performed on the same cycle ergometer. Despite significant locomotor muscle fatigue (P = 0.03), the V˙O2sc was not significantly different between the pre-fatigue (464 ± 301 mL·min−1) and the control (556 ± 223 mL·min−1) condition (P = 0.50). Blood lactate response was not significantly different between conditions (P = 0.48) but RPE was significantly higher following the pre-fatiguing exercise protocol compared with the control condition (P < 0.01) suggesting higher muscle recruitment. These results demonstrate experimentally that locomotor muscle fatigue does not significantly alter the V˙O2 kinetic response to high intensity aerobic exercise, and challenge the hypothesis that the V˙O2sc is strongly associated with locomotor muscle fatigue.

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Cover title.

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Altération de la régénération musculaire dans la maladie pulmonaire obstructive chronique. La maladie pulmonaire obstructive chronique (MPOC) est caractérisée par une obstruction bronchique irréversible et progressive. L’atrophie musculaire périphérique y est fréquente et a un impact négatif sur la capacité fonctionnelle et la survie des sujets atteints. Toutefois, on ignore si une altération du processus de régénération musculaire est un processus ayant cours dans l’atrophie musculaire périphérique. Le but de la présente thèse était donc d’étudier les cellules satellites, principales cellules responsables de la régénération musculaire dans les muscles périphériques de patients ayant une MPOC. Dans un premier temps, nous avons évalué l’historique de réplication du tissu musculaire et la sénescence des cellules satellites. Les changements morphologiques ayant lieu dans le muscle au cours de la progression de la maladie rendent le muscle plus susceptible aux dommages, induisant un raccourcissement prématuré des télomères. Un raccourcissement des télomères chez les sujets ayant une MPOC avec atrophie est concomitant avec une augmentation du nombre de cellules satellites sénescentes et de l’épuisement du potentiel de régénération compromettant le maintien de la masse musculaire chez ces sujets. Dans un deuxième et troisième temps, nous avons étudié les étapes amenant une cellule satellite vers une cellule musculaire dans les muscles périphériques et respiratoires de patients ayant une MPOC comparativement à des sujets contrôles. Les cellules satellites sont impliquées dans la réparation du tissu musculaire. Dans les cellules satellites provenant des sujets ayant une MPOC, une altération de la prolifération et de la différentiation a été observée. Ces résultats sont compatibles avec une altération de la régénération musculaire pouvant conduire à l’atrophie musculaire dans la MPOC. Le quatrième volet de ce projet s’intéressait à l’impact d’un entraînement en résistance sur l’activité des cellules satellites et le rôle joué par la myostatine dans ce contexte. La littérature montre que l’exercice en résistance est bien toléré et aide les patients ayant une MPOC à retrouver une meilleure qualité de vie. Cependant, il semble qu’ils n’y répondent pas tous aussi bien que les sujets contrôles. La capacité de réponse des cellules satellites à un entraînement en résistance semble inadéquate, suggérant ainsi un défaut de leur activation. Dans la dernière étude de cette thèse, nous avons voulu évaluer l’impact de l’inflammation systémique en étudiant SAA1, une protéine de phase aiguë et p21, une protéine du cycle cellulaire dans la dégradation des protéines des cellules musculaires. Les liens de causalité entre l’affection primaire et les différentes comorbidités demeurent nébuleux dans la MPOC. SAA1 et p21 sont augmentés dans les muscles squelettiques des patients ayant une MPOC et par ailleurs, SAA1 est capable d’induire la dégradation des protéines musculaires. Cette thèse expose les premiers éléments impliquant l’altération de la régénération musculaire avec la dysfonction musculaire observée chez les patients ayant une MPOC. Ces résultats vont certainement contribuer au développement de nouvelles thérapies et stratégies d’intervention dans le but d’améliorer la qualité de vie des personnes atteintes d’une MPOC. En somme, les travaux effectués dans le cadre de la présente thèse montrent que plusieurs mécanismes agissent de concert avec l’inactivité physique afin d’induire le phénotype dysfonctionnel dans les muscles des patients ayant une MPOC.

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This dissertation demonstrates an explanation of damage and reliability of critical components and structures within the second law of thermodynamics. The approach relies on the fundamentals of irreversible thermodynamics, specifically the concept of entropy generation due to materials degradation as an index of damage. All failure mechanisms that cause degradation, damage accumulation and ultimate failure share a common feature, namely energy dissipation. Energy dissipation, as a fundamental measure for irreversibility in a thermodynamic treatment of non-equilibrium processes, leads to and can be expressed in terms of entropy generation. The dissertation proposes a theory of damage by relating entropy generation to energy dissipation via generalized thermodynamic forces and thermodynamic fluxes that formally describes the resulting damage. Following the proposed theory of entropic damage, an approach to reliability and integrity characterization based on thermodynamic entropy is discussed. It is shown that the variability in the amount of the thermodynamic-based damage and uncertainties about the parameters of a distribution model describing the variability, leads to a more consistent and broader definition of the well know time-to-failure distribution in reliability engineering. As such it has been shown that the reliability function can be derived from the thermodynamic laws rather than estimated from the observed failure histories. Furthermore, using the superior advantages of the use of entropy generation and accumulation as a damage index in comparison to common observable markers of damage such as crack size, a method is proposed to explain the prognostics and health management (PHM) in terms of the entropic damage. The proposed entropic-based damage theory to reliability and integrity is then demonstrated through experimental validation. Using this theorem, the corrosion-fatigue entropy generation function is derived, evaluated and employed for structural integrity, reliability assessment and remaining useful life (RUL) prediction of Aluminum 7075-T651 specimens tested.