979 resultados para Entraînement en endurance


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Neutrophils serve as an intriguing model for the study of innate immune cellular activity induced by physiological stress. We measured changes in the transcriptome of circulating neutrophils following an experimental exercise trial (EXTRI) consisting of 1 h of intense cycling immediately followed by 1 h of intense running. Blood samples were taken at baseline, 3 h, 48 h, and 96 h post-EXTRI from eight healthy, endurance-trained, male subjects. RNA was extracted from isolated neutrophils. Differential gene expression was evaluated using Illumina microarrays and validated with quantitative PCR. Gene set enrichment analysis identified enriched molecular signatures chosen from the Molecular Signatures Database. Blood concentrations of muscle damage indexes, neutrophils, interleukin (IL)-6 and IL-10 were increased (P < 0.05) 3 h post-EXTRI. Upregulated groups of functionally related genes 3 h post-EXTRI included gene sets associated with the recognition of tissue damage, the IL-1 receptor, and Toll-like receptor (TLR) pathways (familywise error rate, P value < 0.05). The core enrichment for these pathways included TLRs, low-affinity immunoglobulin receptors, S100 calcium binding protein A12, and negative regulators of innate immunity, e.g., IL-1 receptor antagonist, and IL-1 receptor associated kinase-3. Plasma myoglobin changes correlated with neutrophil TLR4 gene expression (r = 0.74; P < 0.05). Neutrophils had returned to their nonactivated state 48 h post-EXTRI, indicating that their initial proinflammatory response was transient and rapidly counterregulated. This study provides novel insight into the signaling mechanisms underlying the neutrophil responses to endurance exercise, suggesting that their transcriptional activity was particularly induced by damage-associated molecule patterns, hypothetically originating from the leakage of muscle components into the circulation.

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Objectives To investigate the frequency of the ACTN3 R577X polymorphism in elite endurance triathletes, and whether ACTN3 R577X is significantly associated with performance time. Design Cross-sectional study. Methods Saliva samples, questionnaires, and performance times were collected for 196 elite endurance athletes who participated in the 2008 Kona Ironman championship triathlon. Athletes were of predominantly North American, European, and Australian origin. A one-way analysis of variance was conducted to compare performance times between genotype groups. Multiple linear regression analysis was performed to model the effect of questionnaire variables and genotype on performance time. Genotype and allele frequencies were compared to results from different populations using the chi-square test. Results Performance time did not significantly differ between genotype groups, and age, sex, and continent of origin were significant predictors of finishing time (age and sex: p < 5 × 10−6; continent: p = 0.003) though genotype was not. Genotype and allele frequencies obtained (RR 26.5%, RX 50.0%, XX 23.5%, R 51.5%, X 48.5%) were found to be not significantly different from Australian, Spanish, and Italian endurance athletes (p > 0.05), but were significantly different from Kenyan, Ethiopian, and Finnish endurance athletes (p < 0.01). Conclusions Genotype and allele frequencies agreed with those reported for endurance athletes of similar ethnic origin, supporting previous findings for an association between 577X allele and endurance. However, analysis of performance time suggests that ACTN3 does not alone influence endurance performance, or may have a complex effect on endurance performance due to a speed/endurance trade-off.

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Purpose The aim of this study was to determine the early time course of exercise-induced signaling after divergent contractile activity associated with resistance and endurance exercise. Methods Sixteen male subjects were randomly assigned to either a cycling (CYC; n = 8, 60 min, 70% V?O2peak) or resistance (REX; n = 8, 8×5 leg extension, 80% one-repetition maximum, 3-min recovery) exercise group. Serial muscle biopsies were obtained from vastus lateralis at rest before, immediately after, and after 15, 30, and 60 min of passive recovery to determine early signaling responses after exercise. Results There were comparable increases from rest in AktThr308/Ser473 and mTORSer2448 phosphorylation during the postexercise time course that peaked 30-60 min after both CYC and REX (P<0.05). There were also similar patterns in p70S6K Thr389 and 4E-BP1Thr37/46 phosphorylation, but a greater magnitude of effect was observed for REX and CYC, respectively (P<0.05). However, AMPKThr172 phosphorylation was only significantly elevated after CYC (P<0.05), and we observed divergent responses for glycogen synthaseSer641 and AS160 phosphorylation that were enhanced after CYC but not REX (P<0.05). Conclusions We show a similar time course for Akt-mTOR-S6K phosphorylation during the initial 60-min recovery period after divergent contractile stimuli. Conversely, enhanced phosphorylation status of proteins that promote glucose transport and glycogen synthesis only occurred after endurance exercise. Our results indicate that endurance and resistance exercise initiate translational signaling, but high-load, low-repetition contractile activity failed to promote phosphorylation of pathways regulating glucose metabolism.

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PURPOSE: We used gene microarray analysis to compare the global expression profile of genes involved in adaptation to training in skeletal muscle from chronically strength-trained (ST), endurance-trained (ET), and untrained control subjects (Con). METHODS: Resting skeletal muscle samples were obtained from the vastus lateralis of 20 subjects (Con n = 7, ET n = 7, ST n = 6; trained [TR] groups >8 yr specific training). Total RNA was extracted from tissue for two color microarray analysis and quantative (Q)-PCR. Trained subjects were characterized by performance measures of peak oxygen uptake V?O 2peak) on a cycle ergometer and maximal concentric and eccentric leg strength on an isokinetic dynamometer. RESULTS: Two hundred and sixty-three genes were differentially expressed in trained subjects (ET + ST) compared with Con (P < 0.05), whereas 21 genes were different between ST and ET (P < 0.05). These results were validated by reverse transcriptase polymerase chain reaction for six differentially regulated genes (EIFSJ, LDHB, LMO4, MDH1, SLC16A7, and UTRN. Manual cluster analyses revealed significant regulation of genes involved in muscle structure and development in TR subjects compared with Con (P < 0.05) and expression correlated with measures of performance (P < 0.05). ET had increased whereas ST had decreased expression of gene clusters related to mitochondrial/oxidative capacity (P ?‰Currency sign 0.05). These mitochondrial gene clusters correlated with V?O2peak (P < 0.05). V?O2peak also correlated with expression of gene clusters that regulate fat and carbohydrate oxidation (P < 0.05). CONCLUSION: We demonstrate that chronic training subtly coregulates numerous genes from important functional groups that may be part of the long-term adaptive process to adapt to repeated training stimuli.

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Re-programming of gene expression is fundamental for skeletal muscle adaptations in response to endurance exercise. This study investigated the time-course dependent changes in the muscular transcriptome following an endurance exercise trial consisting of 1 h of intense cycling immediately followed by 1 h of intense running. Skeletal muscle samples were taken at baseline, 3 h, 48 h, and 96 h post-exercise from eight healthy, endurance-trained, male individuals. RNA was extracted from muscle. Differential gene expression was evaluated using Illumina microarrays and validated with qPCR. Gene set enrichment analysis identified enriched molecular signatures chosen from the Molecular Signatures Database. Three h post-exercise, 102 gene sets were up-regulated [family wise error rate (FWER), P < 0.05]; including groups of genes related with leukocyte migration, immune and chaperone activation, and cyclic AMP responsive element binding protein (CREB) 1-signaling. Forty-eight h post-exercise, among 19 enriched gene sets (FWER, P < 0.05), two gene sets related to actin cytoskeleton remodeling were up-regulated. Ninety-six h post-exercise, 83 gene sets were enriched (FWER, P < 0.05), 80 of which were up-regulated; including gene groups related to chemokine signaling, cell stress management, and extracellular matrix remodeling. These data provide comprehensive insights into the molecular pathways involved in acute stress, recovery, and adaptive muscular responses to endurance exercise. The novel 96 h post-exercise transcriptome indicates substantial transcriptional activity, potentially associated with the prolonged presence of leukocytes in the muscles. This suggests that muscular recovery, from a transcriptional perspective, is incomplete 96 h after endurance exercise involving muscle damage.

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Autonomous navigation and locomotion of a mobile robot in natural environments remain a rather open issue. Several functionalities are required to complete the usual perception/decision/action cycle. They can be divided in two main categories : navigation (perception and decision about the movement) and locomotion (movement execution). In order to be able to face the large range of possible situations in natural environments, it is essential to make use of various kinds of complementary functionalities, defining various navigation and locomotion modes. Indeed, a number of navigation and locomotion approaches have been proposed in the literature for the last years, but none can pretend being able to achieve autonomous navigation and locomotion in every situation. Thus, it seems relevant to endow an outdoor mobile robot with several complementary navigation and locomotion modes. Accordingly, the robot must also have means to select the most appropriate mode to apply. This thesis proposes the development of such a navigation/locomotion mode selection system, based on two types of data: an observation of the context to determine in what kind of situation the robot has to achieve its movement and an evaluation of the behavior of the current mode, made by monitors which influence the transitions towards other modes when the behavior of the current one is considered as non satisfying. Hence, this document introduces a probabilistic framework for the estimation of the mode to be applied, some navigation and locomotion modes used, a qualitative terrain representation method (based on the evaluation of a difficulty computed from the placement of the robot's structure on a digital elevation map), and monitors that check the behavior of the modes used (evaluation of rolling locomotion efficiency, robot's attitude and configuration watching. . .). Some experimental results obtained with those elements integrated on board two different outdoor robots are presented and discussed.

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Endurance exercise can cause immunosuppression and increase the risk of upper respiratory illness. The present study examined changes in the secretion of T helper (Th) cell cytokines after endurance exercise. Ten highly trained road cyclists [mean±SEM: age 24.2±1.7 years; height 1.82±0.02 m; body mass 73.8±2.0 kg; peak oxygen uptake 65.9±2.3 mL/(kg•min)] performed 2 h of cycling exercise at 90% of the second ventilatory threshold. Peripheral blood mononuclear cells were isolated and stimulated with phytohemagglutinin. Plasma cortisol concentrations and the concentration of Th1/Th2/Th17 cell cytokines were examined. Data were analyzed using both traditional statistics and magnitude-based inferences. Results revealed a significant decrease in plasma cortisol at 4–24 h postexercise compared with pre-exercise values. Qualitative analysis revealed postexercise changes in concentrations of plasma cortisol, IL-2, TNF, IL-4, IL-6, IL-10, and IL-17A compared with pre-exercise values. A Th1/Th2 shift was evident immediately postexercise. Furthermore, for multiple cytokines, including IL-2 and TNF (Th1), IL-6 and IL-10 (Th2), and IL-17 (Th17), no meaningful change in concentration occurred until more than 4 h postexercise, highlighting the duration of exercise-induced changes in immune function. These results demonstrate the importance of considering “clinically” significant versus statistically significant changes in immune cell function after exercise.

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La creación del término resiliencia en salud es un paso importante hacia la construcción de comunidades más resilientes para afrontar mejor los desastres futuros. Hasta la fecha, sin embargo, parece que hay poca literatura sobre cómo el concepto de resiliencia en salud debe ser definido. Este artículo tiene como objetivo construir un enfoque de gestión de desastres de salud integral guiado por el concepto de resiliencia. Se realizaron busquedas en bases de datos electrónicas de salud para recuperar publicaciones críticas que pueden haber contribuido a los fines y objetivos de la investigación. Un total de 61 publicaciones se incluyeron en el análisis final de este documento, que se centraron en aquéllas que proporcionan una descripción completa de las teorías y definiciones de resiliencia ante los desastres y las que proponen una definición y un marco conceptual para la capacidad de resiliencia en salud. La resiliencia es una capacidad inherente de adaptación para hacer frente a la incertidumbre del futuro. Esto implica el uso de múltiples estrategias, un enfoque de riesgos máximos y tratar de lograr un resultado positivo a través de la vinculación y cooperación entre los distintos elementos de la comunidad. Resiliencia en salud puede definirse como la capacidad de las organizaciones de salud para resistir, absorber, y responder al impacto de los desastres, mientras mantiene las funciones esenciales y se recupera a su estado original o se adapta a un nuevo estado. Puede evaluarse por criterios como la robustez, la redundancia, el ingenio y la rapidez e incluye las dimensiones clave de la vulnerabilidad y la seguridad, los recursos y la preparación para casos de desastre, la continuidad de los servicios esenciales de salud, la recuperación y la adaptación. Este nuevo concepto define las capacidades en gestión de desastres de las organizaciones sanitarias, las tareas de gestión, actividades y resultados de desastres juntos en una visión de conjunto integral, y utiliza un enfoque integrado y con un objetivo alcanzable. Se necesita urgentemente investigación futura de su medición

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Whilst native French speakers oftentimes collapse accountability to account giving, this paper outlines the shape of an accountability ala française. Reading Tocqueville’s (1835) work highlights that accountability as practiced in Anglo-Saxonc countries has been an offspring of American democracy. An accountability a la française would be characterised by conformance to a set or universal values, the submission of minorities to choices made by the majority, a means obligation as well as the rejection of transparency. [Alors que le francophone réduit généralement l’accountability à la reddition de comptes, cet article esquisse les contours d’une véritable accountability à la française. La lecture de Tocqueville (1835) révèle que l’accountability pratiquée dans les pays anglo-saxons trouve ses origines dans les fondements de la démocratie américaine. En France, l’accountability serait caractérisée par le respect d’un ensemble de valeurs universelles, l’adhésion des minorités aux choix majoritaires, l’absence de discriminations, une obligation de moyens et un rejet de la transparence.]

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This article presents a reflection of the application of multiculturality principles into tertiary educational programs at the University of Los Andes, Bogota Colombia. The main focus of this paper is debating the concept of 'positive discrimination' as a challenge taken by educational centres in societies with cultural diversity populations.

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This article explores a number of social control strategies on individuals and families actioned by the newly created state-national project during the first decades of Colombian XIX century. With special attention on the discourse of urbanity, also named 'civility or good manners', this paper analyses literary sources produced in the time for molding citizens behaviors in order to incorporate the society into the new paradigm of Modernity.

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Detection of faults in roller element bearing is a topic widely discussed in the scientific field. Bearings diagnostics is usually performed by analyzing experimental signals, almost always vibration signals, measured during operation. A number of signal processing techniques have been proposed and applied to measured vibrations. The diagnostic effectiveness of the techniques depends on their capacities and on the environmental conditions (i.e. environmental noise). The current trend, especially from an industrial point of view, is to couple the prognostics to the diagnostics. The realization of a prognostic procedure require the definition of parameters able to describe the bearing condition during its operation. Monitoring the values of these parameters during time allows to define their trends depending on the progress of the wear. In this way, a relation between the variation of the selected parameters and the wear progress, useful for diagnostics and prognostics of bearings in real industrial applications, can be established. In this paper, a laboratory test-rig designed to perform endurance tests on roller element bearing is presented. Since the test-rig has operated for a short time, only some preliminary available results are discussed.

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Este proyecto se desarrollo por iniciativa de las autoras y con el apoyo de un grupo interdisciplinario, con el interés común de desarrollar una investigación académica cuyo resultado sea de utilidad para el desarrollo del sector productivo artesanal Peruano. El proceso de investigación nace a partir de una observación de campo acerca de la problemática del producto artesanal Peruana y enfocada en los aspectos comerciales, de diseño y producción. Esta observación se centro en Cajamarca (por ser el departamento menos intervenido por otras investigaciones en este tema) en la zona de Aylambo y Cruz Blanca, en los talleres artesanales que desarrollan productos cerámicos. A partir de un análisis de tipo FODA de los productos y de su contexto de desarrollo, encontramos que los artesanos que trabajan con los empresarios exportadores, requieren un tipo de capacitación que les permita desarrollar su trabajo mediante un proceso orientado a cumplir con exigencias técnicas y de diseño para el desarrollo de productos validos como oferta exportable. Como punto de partida se recurrió a las instituciones no gubernamentales y del gobierno, que promueven el sector artesanal Peruano (Prompex, Adex, Proyecto PARA, IMPART) para conocer su opinión respecto a los mercados objetivos de este sector, y para adoptar como parte del proyecto, lo vigente respecto a las políticas y planes de comercialización. Para entender la contraparte comercial de este sector artesanal recurrimos a empresas privadas exportadoras con muchos años de experiencia, para ello contamos con la colaboración de empresas como Allpa, Manos Amigas, Novica. A partir de la observación de campo preliminar y de la información recogida de los expertos consultados, se realizo un diagnostico de la situación productiva en este sector. En base a la definición del problema, se establecieron las estrategias y metodologías para el diseño de la investigación, siendo parte de estas estrategias, la realización de un taller de desarrollo de productos en Cajamarca. Las estrategias tuvieron como enfoque principal la definición de metodologías de trabajo, cuya aplicación sea posible en el marco del contexto económico, político y cultural en el que se desarrolla este sector en la realidad inmediata del país. El proyecto culmina con la presentación de una propuesta que mas allá de abarcar únicamente lo metodológico en el área del diseño, presenta también ‘modelos’ de trabajo entre los diferentes actores que intervienen en el sector, de manera que a través de estrategias colaborativas se pueda potenciar el crecimiento del sector y beneficiar el desarrollo del artesano.

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Det har nu gått mer än tio år sedan en student vid Northeastern University i USA lanserade den första fildelningstjänsten som blev framgångsrik bland den breda allmänheten (e.g. Alderman 2001). Lanseringen av tjänsten, som kallades Napster, ses ofta som inledningen på ett av de mest dramatiska decennierna i musikbranschens historia. En lång rad internetbaserade tjänster som följt i Napsters spår har gjort det möjligt att sprida musik till miljontals användare utan att upphovsmän och rättighetsinnehavare fått någon ersättning. Katt-och-råtta-leken mellan lagstiftning och teknik har varit intensiv och har utvecklats till ett av decenniets allra hetaste diskussionsämnen bland politiker och ledarskribenter. Försäljningen av inspelad musik har sjunkit dramatiskt och musikbranschen har tvingats ifrågasätta många väletablerade sanningar. Det här kapitlet belyser ett antal fundamentala aspekter av denna förändring och utforskar några av den ”nya” musikbranschens viktigaste karaktäristika. Under den tid som musikbranschen har beforskats har vanligtvis betoningen legat på fonogrammen, det vill säga den del av branschen som rör produktion och konsumtion av inspelad musik. På grund av branschens förändrade struktur kommer dock det här kapitlet att vidga perspektivet en smula och även inkludera musikbranschens andra delar som exempelvis konserter och förlagsverksamhet...