La mitochondrie est le siège principal de la production d’énergie sous forme d’ATP en conditions aérobies, mais aussi d’espèces réactives dérivées de l’oxygène (ROS). La fonction mitochondriale est étroitement liée à la production de ROS puisque ces derniers, selon leur taux, peuvent altérer ou optimiser le rendement énergétique. La plasticité structurale et fonctionnelle de la mitochondrie est essentielle au maintien de l’homéostasie dans toute situation qui nécessite des ajustements métaboliques comme l’exercice physique. Les mécanismes adaptatifs de la fonction mitochondriale et des ROS lors de l’entrainement sont encore loin d’être élucidés ainsi que l’impact du genre sur ces réponses. Dans cette perspective, deux modèles animaux (rat Wistar et anguille européenne) ont été choisis. Les effets d’un entrainement en endurance de même intensité (70% de la vitesse maximale aérobie de course ou de nage) ont été étudiés chez le rat Wistar et l’anguille européenne argentée. Cette dernière est une espèce endurante capable d’effectuer une migration de reproduction de 6000 km et caractérisée par un dimorphisme sexuel de taille. Des mesures in vitro de la consommation d’oxygène, la production radicalaire et d’ATP ont été effectuées simultanément à partir de fibres perméabilisées de cœur et de muscle squelettique. La vulnérabilité ou résistance de la fonction mitochondriale à l’exposition à un système générateur de ROS (mimant un stress oxydant) a également été étudiée. Avant entrainement, chez le rat Wistar, la femelle présente une fonction mitochondriale plus efficiente énergétiquement et plus résistante aux ROS, alors que chez l’anguille, ce profil métabolique et radicalaire est plutôt observé chez le mâle. Après entrainement, quelle que soit l’espèce, la meilleure performance physique observée s’accompagne de modifications métaboliques et radicalaires différentes selon le genre et l’espèce. Chez le rat, l’amélioration de la fonction mitochondriale se traduit différemment selon le sexe. Chez le mâle, l’entrainement induit une amélioration du rendement énergétique via un meilleur couplage entre oxydation et phosphorylation et/ou une meilleure utilisation des électrons au niveau de la chaine respiratoire. Chez la femelle, l’augmentation de la production d’ATP serait liée à l’augmentation de la consommation d’oxygène mitochondriale. Comme chez le rat, l’entraînement induit globalement chez l’anguille une amélioration du rendement énergétique et de la résistance de la fonction mitochondriale aux ROS, mais uniquement chez le mâle. L’ensemble de ces résultats montre des réponses métaboliques et radicalaires dépendantes du genre. Quelle que soit l’espèce, l’entrainement semble être chez le mâle plus bénéfique que chez la femelle en termes d’efficacité énergétique mitochondriale et de résistance de la fonction mitochondriale à un stress oxydant. Dans le contexte de la migration de l’anguille, ces adaptations permettraient au mâle, largement plus petit que la femelle, une efficacité de nage supérieure, permettant leur synchronisation d’arrivée sur le lieu de reproduction. Les similitudes interspécifiques de réponse à l’entraînement selon le genre confortent l’intérêt d’utilisation du modèle poisson dans le champ de la physiologie de l’exercice. / Mitochondrion is the main site of aerobic energy (ATP) and reactive oxygen species (ROS) productions. Mitochondrial function is closely linked to ROS, which, according their rate, can alter or optimize energy efficiency. Structural and functional plasticity of mitochondria is essential to maintain homeostasis in any situation that requires metabolic adjustments as physical exercise. The adaptive mechanisms of mitochondrial function and ROS during training and the impact of gender on these responses are still far from being solved. In this perspective, two animal models (Wistar rat and European eel) were chosen.The effects of endurance training of the same intensity (70% of maximal aerobic speed running or swimming) were studied in Wistar rat and silver European eel. The latter is an enduring species capable of performing a spawning migration of 6000 km and characterized by sexual dimorphism in size. In vitro measurements of oxygen consumption, free radical and ATP productions were carried out simultaneously from heart and skeletal muscle permeabilized fibers. The vulnerability or resistance of the mitochondrial function to a ROS generating system exposure (mimicking oxidative stress) was also studied.Before training, in rat, female has a mitochondrial function energetically more efficient and more resistant to ROS, whereas in eel, this metabolic and radical profile is observed rather in male. After training, whatever the species, the improved physical performance observed is associated with various metabolic and radical changes which depending on gender and species. In rats, the improving of mitochondrial function translates differently according to gender. In male, training induces improvement in energy efficiency through a better coupling between oxidation and phosphorylation and/or better use of electrons at the respiratory chain level. In female, increasing in ATP production may be related to the increase in mitochondrial oxygen consumption. As in rats, training induces globally in eel an improvement in energy efficiency and resistance of mitochondrial function to ROS, but only in male. All these results show metabolic and radical responses depending on gender. Whatever the species, training seems to be most beneficial in males than in females in terms of mitochondrial energy efficiency and resistance of mitochondrial function to oxidative stress. In the context of eel migration, these adaptations allow to male, largely smaller than female, a higher swim efficiency, allowing their synchronization on breeding site. Interspecific similarities in training response by gender confirm the interest of fish model’s using in the field of exercise physiology.

Exercise intensity and its distribution is probably the most important and most heavily debated variable of endurance training. Training induces adaptation but also induces stress responses. Controlling the training-intensity distribution may provide a mechanism for balancing these two effects. It has been reported that elite endurance athletes train with a high volume and load, relative to the sport. These athletes spend the vast majority (>80%) of training time at relatively low intensities (lower than the lactate threshold, zone one), and therefore <20% of training time above the lactate threshold (zones two and three). Experimental studies support the beneficial effects of a high training volume in zone one, and show detrimental effects of replacing zone one training with training in zone two. This is likely due to enhanced recovery from training in zone one compared with training in zone two. The acute recovery following training sessions in zones two and three has been reported to not be different, but the recovery following training in zone one has been reported to be faster. Improvements in physiological adaptation and endurance performance have been reported to be greater following training programmes with higher exercise intensities. Therefore, it has been suggested that a polarised training model, which includes ~80% of training in zone one with ~20% of training in zone three is more beneficial than a threshold training model, with the majority of training in zone two. However, research into an optimal training-intensity distribution is limited. Therefore, the aims of this thesis were to assess the effectiveness of training-intensity distribution on the improvements in physiological adaptation, endurance performance and assess if manipulating training-intensity distribution had an effect on immune function. Study one revealed that the lactate threshold, the lactate turnpoint and maximal performance measures in swimming, cycling and running, assessed using the methods outlined in the study, are reproducible in trained endurance athletes. These tests can therefore be used by trained endurance athletes as part of a physiological testing programme to assess not only endurance performance, but also to demarcate training intensity zones for exercise intensity prescription and monitor moderate to large adaptations to training. Practitioners should take care when deciding on the duration between tests to test for adaptations from training, as adaptations need to be greater than these detected test-retest variations to be considered physiologically meaningful. To the best of the author’s knowledge, study two was the first study to have assessed training-intensity distribution in a group of multisport athletes. Training was monitored over a 6-month period, and testing took place every two months to assess the effect of the training on physiological adaptation. Although speculative due to the number of variables involved, the results suggest that a greater proportion of training time spent in zone one and a lower proportion of training time spent in zone two is beneficial to physiological adaptation. However, given the number of variables associated with assessing the training-intensity distribution in multisport athletes, it is not easy to draw conclusions as to the effectiveness of the training in the different disciplines on the key measures of adaptation in the different disciplines. Study two highlighted the need for future research to focus on experimental manipulation of training-intensity distribution and thus improve our understanding of its impact on the training-induced adaptations in endurance athletes. Study three manipulated the training-intensity distribution in trained endurance athletes in just one discipline, to reduce the number of variables involved. A polarised training model was compared to a threshold training model on the effectiveness to improve physiological adaptation and endurance performance. Results revealed that a polarised training model is recommended for trained cyclists wishing to maximally improve performance and physiological adaptation over a short-term (six week) training period. The first part of study four assessed the effect of a polarised and a threshold training model on immune function markers in trained cyclists. Both endurance training programmes had similar volume, and were sufficient to induce improvements in performance and physiological adaptation. However, despite likely differences in recovery, both training programmes had no effect on the proportion of low or high differentiated or senescent CD8+ or CD4+ T-cells in blood. Therefore, training adaptation was achieved at no cost to this particular aspect of immune function. From these results and evidence from previous studies, it seems likely that athletes need to be overreached to induce any change in immune function following a period of intensified training. The second part of study four assessed the impact of an ironman triathlon race on Epstein-Barr virus (EBV) and Varicella-Zoster virus (VZV) antibody titres and the frequency of low and high differentiated and senescent blood T-cells in trained endurance athletes. Previous work has revealed that an ironman triathlon race increases the proportion of senescent CD4+ T cells and decreases the proportion of naive CD4+ T cells, and thus induces changes the immune space which could leave an individual at a greater risk of infection. This study however, did not find any changes in the proportions of these T cell subsets following an ironman triathlon race. The mean results of this study suggest that there is no relationship between EBV and VZV-specific antibody concentrations and the proportion of senescent, low and highly differientiated T cells. However, on analysis of individual subject data, it seems possible that subjects with a high antibody titre for EBV or VZV 3 wks before a competition might be more at risk of infection post race. A greater subject number would be needed in order to make a more conclusive statement about this relationship. The results of this thesis suggest that future research is required in the area of training-intensity distribution. Firstly, our understanding of the physiological mechanisms responsible for the effectiveness of a polarised training model in trained endurance athletes is limited, and thus studies should attempt to address this issue. Our current knowledge on the mechanisms underlying a blunted T cell response following strenous exercise is also limited. A change in the immune space to a greater proportion of senescent T cells and a lower proportion of naive T cells might contribute to this blunted response. In the current thesis however, the proportions of these T cell markers were unchanged following the training/racing interventions. It is possible that with a higher training load, there could be changes in these markers, and thus this is an exciting area that could have potential implications on athlete health. Finally, testing for antibody titres in endurance athletes is possibly an avenue to detect individuals at the greatest risk of infection if subjected to a large physical and/or mental stress. This could have implications on maintaining athlete health and therefore, allowing athletes to train consistently.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

Diverses études épidémiologiques ont mis en évidence une relation étroite entre pollution urbaine au monoxyde de carbone (CO) et mortalité cardiovasculaire. Récemment il a été mis en évidence, chez le rat, qu'une exposition prolongée à ce polluant urbain avait pour conséquence le développement d'un phénotype cellulaire pathologique, pouvant influencer la vulnérabilité du coeur à un stress aigu. L'objectif de nos travaux était donc i) d'évaluer l'impact de la pollution au CO, sur la sensibilité du myocarde de rats au syndrome d'ischémie-reperfusion (IR) ; et ii) d'évaluer les effets potentiellement cardioprotecteurs d'un exercice pratiqué régulièrement à intensité modérée, sur le remodelage phénotypique cellulaire myocardique. Pour cela, 187 rats Wistar ont été séparés en 3 groupes : des rats contrôles, des rats exposés pendant 4 semaines au CO (30-100 ppm), et des rats entraînés en endurance avant d'être exposés au CO. La sensibilité à l'IR était évaluée par ischémie régionale réalisée sur modèle de coeur isolé perfusé de Langendorff. La fonction et les mouvements calciques de cardiomyocytes isolés était évalués en condition basale et consécutivement à un protocole d'anoxie-réoxygénation. Les résultats de ce travail confirment l'apparition d’un phénotype pathologique chez les rats exposés de façon prolongée au CO. Ce phénotype pathologique caractérisé dans notre travail par une altération de l’homéostasie calcique et du statut redox cellulaire ainsi qu'une expression tissulaire de iNOS apparait comme à l'origine de la plus grande vulnérabilité du coeur à un stress d’IR. Un autre résultat majeur de ce travail est qu’une stratégie de cardioprotection par un exercice d'intensité modérée pratiqué de manière régulière, permet de prévenir le remodelage pathologique cardiomyocytaire et ainsi l'augmentation de la sensibilité du myocarde à l'IR / Epidemiological studies suggested that carbon monoxide (CO) urban air pollution is mainly related to cardiovascular mortality. In addition, recent experimental studies have highlighted that CO exposure was responsible for the development of cardiomyocytes’ pathological remodeling, which can render the heart more vulnerable to acute stresses. Therefore, the aim of this experimental work was to i) evaluate the impact of prolonged exposure to simulated CO urban pollution on the sensitivity of the myocardium to IR ; and ii) evaluate potential cardioprotective effects of regular bouts of endurance training in this model. 187 Wistar rats were separated into 3 groups : control rats, CO rats exposed during 4 weeks to CO (30-100 ppm), and CO exercised rats. Myocardial sensibility to IR was evaluated with a regional ischemia performed on a Langendorff model of isolated heart. Moreover, the cardiomyocytes’ function and calcium handling were evaluated at basal conditions, following a protocol of cellular anoxia and reoxygenation. The results of this study confirm that chronic exposure to CO is responsible for cardiac phenotypic changes, which are characterized in this work by an imbalance in the cardiomyocytes’ oxidative status, an impairment of calcium handling and iNOS expression. These phenotypic changes were associated in this work with higher heart vulnerability to IR. Another major result of this study is that regular bouts of endurance training conducted prior to CO exposure prevented the pathological cardiac remodeling, consequently leading to higher heart vulnerability due to IR

Fundação de Apoio a Pesquisa e à Inovação Tecnológica do Estado de Sergipe - FAPITEC/SE / Since it was introduced in the United States in 2001, Kettlebell training has grown exponentially among professional and amateur athletes from different sports. The main argument used by disseminators of this methodology was the fact that their ballistic exercises would be efficient to generate positive adaptations in muscle strength and power and cardiorespiratory endurance simultaneously, as well as being an extreme energy consumption activity. Such statements are currently supported by respected scientific publications however; it is not yet scientifically clear whether there is different adaptations between the two most common ways of practicing the swing, a fundamental exercise in Kettlebell training. Just as it´s unclear what is the best dose to prescribe for each goal during kettlebell training. Two studies were then developed with the following objectives: a) to compare the two most common forms of execution of the swing exercise, unilateral and bilateral (study one); b) to compare two typical kettlebell training routines with different volume and intensity (study two). Participated in this research physically active university students without experience (study one) or experience (study two) in kettlebell training. The results of our studies suggest that: a) the two forms of the swing exercise, unilateral and bilateral, are effective to improve the quality of motion muscle strength and cardiorespiratory endurance; b) Regardless of the volume and intensity used in the protocol of this study, the total training load was primarily responsible for the significantly positive response in the quality of movement, strength and cardiorespiratory endurance. / Desde que foi reintroduzido nos Estados Unidos em 2001, o treinamento com Kettlebell cresceu exponencialmente entre atletas profissionais e amadores das mais diversas modalidades. O principal argumento utilizado pelos disseminadores desta metodologia foi o fato de que seus exercícios balísticos seriam eficientes para gerar adaptações positivas na força e potência muscular e na resistência cardiorrespiratória simultaneamente, além de ser uma atividade de extremo consumo energético. Tais afirmações são atualmente suportadas por respeitadas publicações científicas entretanto, ainda não está claro cientificamente se existe diferentes adaptações entre as duas formas mais comuns de praticar o swing, exercício fundamental no treinamento com Kettlebell. Assim como, também não é de conhecimento científico, a dose de treinamento com kettlebell mais eficiente para que ocorram positivas adaptações nas capacidades físicas. Foram então desenvolvidos dois estudos com os seguintes objetivos: a) Comparar as duas formas mais comuns de execução do exercício swing, unilateral e bilateral (estudo um); b) Comparar duas típicas rotinas de treinamento com kettlebell com diferentes volume e intensidade (estudo dois). Participaram desta pesquisa estudantes universitários fisicamente ativos, sem experiência (estudo um) ou com experiência (estudo dois) em treinamento com kettlebell. Os resultados dos nossos estudos sugerem que: a) As duas formas de execução do exercício swing, unilateral e bilateral, são eficazes para melhorar a qualidade de movimento, a força muscular e a resistência cardiorrespiratória; b) Independentemente do volume e da intensidade utilizados no protocolo deste estudo, a carga total de treinamento foi o principal responsável pela resposta significativamente positiva na qualidade de movimento, na força e na resistência cardiorrespiratória.

Orientador: Mary Anne Heidi Dolder / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-15T21:18:52Z (GMT). No. of bitstreams: 1 Monteiro_JulianaCastro_D.pdf: 3195959 bytes, checksum: df90aa1ceb6206d4b8d1a040083df0c7 (MD5) Previous issue date: 2010 / Resumo: Este estudo investigou os efeitos da infusão de Heteropterys aphrodisiaca no músculo esquelético, tendão e osso de ratos submetidos ao treinamento de endurance. Ratos Wistar machos foram agrupados da seguinte maneira: CS-controle sedentário, HS-H. aphrodisiaca sedentário, CT-controle treinado, HT-H. aphrodisiaca treinado. O protocolo de treinamento consistiu de corrida em esteira motorizada, cinco vezes por semana, com aumento semanal de velocidade e duração. Os animais dos grupos controle receberam água, enquanto HS e HT receberam infusão de H. aphrodisiaca, diariamente, por gavagem durante 8 semanas, correspondente ao período de treinamento. O sangue foi coletado para dosagem de testosterona. O músculo extensor longo dos dedos (EDL), tendão calcanear e a tíbia foram congelados para análises histoquímicas, bioquímicas, biomecânicas e para Western Blot, ou preservados em fixador Karnovsky, sendo posteriormente processados para análises morfométricas e estereológicas utilizando microscopia de luz e eletrônica. O conteúdo de hidroxiprolina, a tensão máxima e o módulo de elasticidade aumentaram (p<0,05) nos tendões dos animais do grupo HT. A atividade da metalopeptidase-2 foi reduzida significativamente nos tendões dos animais do grupo HT. A região de compressão dos tendões dos animais do grupo HT apresentou intensa metacromasia, o que sugere aumento na concentração de glicosaminoglicanos nessa região tendão. Foi observada intensa birrefringência nas regiões de tensão e compressão dos tendões dos animais do grupo HT, o que pode indicar maior nível de organização dos feixes de colágeno. Os níveis de testosterona plasmáticos e a concentração de receptores de andrógeno no músculo esquelético aumentaram significativamente nos animais do grupo HS. A área média de secção transversa das fibras musculares dos animais do grupo HT foi semelhante à área das fibras dos animais sedentários, e aumentou significativamente quando comparados com os animais do grupo CT. A vascularização intramuscular e a densidade volumétrica de mitocôndria foram significativamente maiores nos animais do grupo HT. Nenhuma alteração foi observada nos tipos de fibras musculares para todos os grupos. Os animais do grupo HT mostraram significativo aumento de força e tensão no limite elástico durante o teste biomecânico da tíbia. O conteúdo de colágeno e os dados morfométricos da tíbia não foram alterados nos diferentes grupos. A força e tensão máxima, rigidez e módulo de elasticidade da tíbia foram semelhantes em todos os grupos experimentais. As microscopia eletrônica de varredura mostrou aumento de lacunas e canais de Havers nos ossos dos animais treinados, além disso, os ósteons estavam mais desorganizados quando comparados com os ossos dos animais sedentários. Essas alterações podem indicar que os ossos dos animais treinados estavam sendo remodelados. Portanto, com oito semanas de treinamento não foi possível verificar alterações nas medidas morfométricas, composição e nas propriedades mecânicas (rigidez e módulo de elasticidade) dos ossos dos animais treinados e/ou tratados com a infusão da planta. Por outro lado, a associação do treinamento de endurance com H. aphorodisiaca resultou em tendões mais resistentes para suportar as altas cargas geradas pelas contradições musculares repetidas, aumentou a área de secção transversa das fibras musculares, a densidade volumétrica de mitocôndrias e a vascularização do músculo, assim, sugerindo um aumento da capacidade de endurance dos animais. / Abstract: This study investigated the effects of Heteropterys aphrodisiaca infusion on the skeletal muscle, tendon and bone of rats under endurance training. Male Wistar rats were grouped as follows: CS- control sedentary, HS- H. aphrodisiaca sedentary , CT-control trained, HT- H. aphrodisiaca trained. The training protocol consisted in running on a motorized treadmill, five times a week, with weekly increase in treadmill velocity and duration. Control groups received water while the HS and HT groups received H. aphrodisiaca infusion, daily, by gavage for the 8 weeks of training. The blood was collected for testosterone dosage. Extensor digitorum longus (EDL) muscle, Achilles tendons and tibiae were frozen for histochemical, Western Blotting, biochemical and biomechanical analylis or preserved in Karnovsky's fixative, then processed for morphological analysis by light microscopy and electron microscopy. Biomechanical analysis showed significant increase (p<0.05) in maximum stress and modulus of elasticity of the tendons of the HT animal. The metalloproteinase-2 activity was reduced in the HT tendons. The compression region of tendons of HT animals had a stronger and more intense metachromasy, which suggests increase in glycosaminoglycan concentration in this region of the tendon. The most intense birefringence was observed in both compression and tesion regions of the tendon of HT animals, which may indicate a higher organizational level of collagen bundles. The tendon hidroxyproline content increased significantly is HS animals. The EDL mean cross-section area of HT group was similar to sedentary groups and increased significantly when compared with CT group. The intramuscular vascularization and mitochondria volume density were significantly greater in the HT group compared with other groups. No alterations were observed in the muscle fiber composition for all groups. The HT group showed significantly higher yield load and yield stress in the tibiae three-point bending test. The tibiae collagen content, morphometrical data were not significantly different for the four groups. The maximum load, stiffness, maximum stress and elastic modulus were statistically similar for all for the experimental groups. Scanning electron microscopy showed more lacunae and Havers canals in the bone of trained animals, moreover the osteons were more disorganized, when compared with sedentary groups. These alterations may indicate that the bone of trained animals was being remodeled. Possibly, the duration of training in this study was not sufficient to alter the bone morphometrical measurements, composition and mechanical properties (stiffness and modulus of elasticity) of the trained and treated animals. On the other hand, the association of endurance training with H. aphrodisiaca resulted in more resistant tendons to support high loads from repeated muscle contraction. Also, the association of H. aphrodisiacaI and the exercise protocol increased the mean area of muscle fiber, mitochondrial volume density and muscular vascularization , suggesting an increase of the endurance capacity of these animals. / Doutorado / Biologia Celular / Doutor em Biologia Celular e Estrutural

Le métabolisme lipidique est stimulé lors de l'exercice musculaire. La contribution énergétique des lipides s'accentue pendant l'exercice d'endurance d'intensité modérée de longue durée (40% à 60% de VO2max). Outre les acides gras circulants, les réserves de lipides intramyocellulaires (IMCL) sont sensées être utilisées pendant des performances dépassant 4 heures. Devant le manque de preuves expérimentales jusqu'à ce jour, une 1ere étude a été entreprise sur 10 sportifs (40 ± 6 ans) lors d'une course de 24h. Les résultats obtenus sur le muscle vaste externe ont montré une baisse significative d'IMCL de 56% et 45% dans les fibres de type I et IIA respectivement, alors que le glycogène n'a diminué que dans les fibres I. Ces données indiquent un catabolisme d'IMCL plus efficace que celui du glycogène dans les fibres rapides lors de l'exercice d'ultra endurance, dont le mécanisme reste à déterminer. IMCL s'accumule lors du vieillissement ou de l'obésité et peut constituer un risque de résistance à l'insuline (RI). Un entraînement combiné en endurance (EE) et en résistance (ER) de 14 semaines a été mené sur des sujets âgés (73 ± 4 ans) et d'autres en surpoids (58 ± 5 ans). Dans les deux groupes IMCL a augmenté (p<0.05) dans le muscle vaste externe (après EE) mais est resté stable dans le muscle deltoïde (après ER) et s'est accompagné de l'augmentation (p<0.05) de la capacité enzymatique de la β-oxydation après EE. Les céramides musculaires, une classe de lipides impliquée dans RI, ont été diminués (p=0.052) par EE et non par ER. Ces résultats confirment que l'augmentation d'IMCL n'est pas un facteur de risque métabolique et que EE se traduit par une diminution des céramides et de RI / Lipid metabolism is involved during muscle exercise. Energetic contribution of lipids increases during long lasting endurance exercise of moderate intensity (40% à 60% of VO2max). As well as circulating free fatty acids, intramyocellular lipid storages (IMCL) are postulated to be used during performances longer than 4 hours. Due the the lack experimental evidences untill today, a first study was undertaken on 10 athletes (40 ± 6 yrs) during a 24h running. Results obtained on vastus lateralis muscle showed a significant 56% and 45% decrease of IMCL in type I and IIA fibres respectively while glycogen decreased only in type I fibres. These data indicate a more efficient catabolism of IMCL than those of glycogen in fast twitch fibres during ultra endurance exercise, of which mechanism remains to be explored. IMCL accumulates during ageing or overweighting and may constitute a risk of insulin resistance (IR). A combined 14 weeks endurance (ET) and resistance (RT) training was followed by older (73 ± 6 yrs) and overweighted (58 ± 5 yrs) subjects. In the two groups IMCL increased (p<0.05) in vastus lateralis muscle (after ET) but remained stable in deltoidus muscle (after RT) and was linked to an increase (p<0.05) of β-oxydation enzymatic capacity after ET. Muscle ceramides, a category of lipids implicated in IR, decreased (p=0.052) after ET and not after RT. These results confirm that increase in IMCL is not a metabolic risk factor and that ET induces a decrease of both ceramides and IR

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Bidrog långdistanslöpning till att sätta fart på människans evolution? Flertalet forskare argumenterar för att långdistanslöpning var en viktig drivkraft i människans evolution. Men har den här teorin ben att stå på? Arkeologiska fynd visar att släktena Homo och Pan skiljdes åt för 4,6 till 6,2 miljoner år sedan. Det är vid den här tiden människans förfader gick sin egen väg med andra ord och blev bipedala. Trots att bipedala gångarter inkluderar gång och löpning, anses löpning inte generellt ha spelat en stor roll i människans evolution eftersom människan är, likt andra hominider, underlägsna sprinters jämfört med de flesta fyrfotade däggdjur. Den här uppsatsen, baserad på en kvalitativ metod med en abduktiv ansats, kommer att bedöma hur bra människan är på fortlöpande långdistanslöpning och narrativt granska den fysiologiska kapaciteten att springa långa distanser hos människor och andra däggdjur. Långdistanslöpning och löpning i allmänhet ställer dock en del fysiska krav på kroppens rörelse- och stödjeapparat. Tack vare en mångfald av fysiologiska egenskaper som möter dessa krav presterar människan anmärkningsvärt bra på att springa långa distanser. Dessa fysiologiska egenskaper kan delas in i fyra krav löpning utsätter kroppen för; energetik, muskuloskeletal styrka, stabilitet och temperaturreglering, varav många lämnar spår i skelettet. De fossila spåren av dessa egenskaper tyder på att förmågan att springa uppkom inom det mänskliga släktet och att löpning kan ha varit en bidragande faktor till utvecklandet av den mänskliga kroppsformen. / Did endurance running drive human evolution? Some researchers argue that endurance running was a key driving factor of human evolution. But does this theory have legs? Archaeological finds show that bipedalism is a key derived behaviour of hominins that originated after the divergence of the human and chimpanzee lineages. Although bipedal gaits include walking and running, running is generally considered to have played no major role in human evolution because humans, like other hominids, are poor sprinters compared to most quadrupedal terrestrial mammals. In this paper, based on a qualitative method with an abductive reasoning, I assess how well humans perform at sustained long-distance running and narratively review the physiological bases for endurance running capabilities in humans and other mammals. Endurance running and running in general expose the locomotor system for several physiological demands. Thanks to a diverse array of features that meet these demands, humans perform remarkably well at endurance running. These features can be divided into four types of demands posed by endurance running; energetics, musculoskeletal strength, stabilization and thermoregulation. Many of these features have left traces in the fossilized skeleton of early hominins for paleoanthropologist and other researchers to examine. The fossil evidence of these features suggests that endurance running originated in the genus Homo and may have been a contributing factor in the evolution of the human body form.

Thesis (MA)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: The small Middle Eastern country of Lebanon was once recognised as the exemplar of power-sharing democracy, upholding a system that promoted peace and coexistence between Christians and Muslims. Power was divided proportionally amongst confessional groups, granting each sect power according to their demographic proportion. This division of power was aimed at promoting national unity, but changes in the Lebanese demography made the division undemocratic, and the constitution no longer accurately represented Lebanese society. The 1926 constitution, supplemented by the National Pact in 1943, which had upheld this division of power, baulked under the pressure of a 15-year civil war, to the surprise of many scholars who had praised the Lebanese system. While many place the blame on the outside influences, it has been determined that the problem lay within the system. The static characteristic of the system did not sufficiently provide for changing demographics, or a change in interest groups. The problem lay in the fixed nature of the proportionality of the consociational system. The prolonged civil war, sometimes referred to as a proxy war between Israel and Syria, came to an end with the signing of the Taif Accord in 1990. Though none were satisfied with its provision, the Accord brought an end to the escalating violence. The Accord paved the way for the rebuilding of state institutions, enabling parliamentary elections in 1992 and 1996; general municipal elections in 1998; the peaceful transfer of power between presidents; as well as the reconstruction of the Lebanese economy. The main objective of this study of Lebanon is to determine whether the amended Lebanese constitution of 1990 adheres to the principles provided in the theoretical framework regarding constitutional endurance. This study is in the form of a qualitative case study. It aims to describe, at length, and to form an in-depth understanding of the actors and events leading up to the Taif Accord, as well as the formation and implementation thereof. The research questions include: What factors relating to flexibility, specificity and inclusion contributed to the breakdown of the 1943 National Pact?; What steps were taken leading to the Taif Accord?; and Have the changes made in the Lebanese constitution by means of the 1990 Taif Accord facilitated the endurance of the constitution? The study aims to contribute through its application of the theoretical framework to a particular case study, namely that of Lebanon. By 'testing' this theoretical framework, this study also provides an in-depth analysis of the happenings in Lebanon over the past 80 years. It remains in question whether the Taif Accord‟s amendments to the constitution have sufficiently provided for the resilience of thereof. Twenty years of relative peace have not convinced Lebanese citizens of the legitimacy and efficacy of the Accord. While the over-centralisation of power within the system was curbed by shifting power away from the president to a cabinet equally divided between Christian and Muslims, the Accord failed to effectively deal with the preset nature of the proportionality within the system. 20 years of relative peace may be enough to ensure the endurance of the constitution, but regional factors as well as the presence of radicalised groups play an important role in destabilising the fragile balance within the country. Should the Lebanese state continue to be inclusive and flexible in the wake of a constantly changing environment, it may endure. However, the tumultuous nature of the region in which Lebanon finds itself may eventually provide external shocks that the Lebanese system fails to weather. The hope is that the system builds on sound, systemic foundations in order to be able to endure regional conflict. / AFRIKAANSE OPSOMMING: Die klein Midde-Oosterse land Lebanon, was vroeër 'n voorbeeld van 'n magsdelende demokrasie wat 'n stelsel gehandhaaf het wat vrede en naasbestaan tussen Christene en Moslems bevorder het. Mag is proporsioneel onder geloofsgroepe verdeel volgens hul demografiese verhouding tot die ander groepe. Hierdie verdeling van mag was gemik op die bevordering van nasionale eenheid, maar veranderinge in die Lebanese demografie het veroorsaak dat die grondwet nie meer verteenwoordigend was van die Lebanese samelewing nie. Die Lebanese Grondwet van 1926, tesame met die Nasionale Verdrag van 1943, wat hierdie verdeling gehandhaaf het, het onder die druk van 'n 15-jare Burgeroorlog inmekaar gestort, ten spyte van die vertroue wat in die stelsel was. Alhoewel die skuld soms op eksterne invloede geplaas is, is dit egter bepaal dat die probleem in die Lebanese stelsel self lê. Die statiese kenmerk van die stelsel het nie voldoende voorsiening gemaak vir 'n verandering in die demografie of belangegroepe nie. Die probleem lê in die statiese en onwrikbare aard van die konsosiatiewe stelsel. Die uitgerekte Burgeroorlog, soms gesien as 'n oorlog tussen Israel en Sirië op Lebanese grond, is tot 'n einde gebring met die ondertekening van die Taif Verdrag in 1990. Alhoewel geen betrokke party ten volle tevrede was met die bepalinge van die Verdrag nie, het dit 'n einde gebring aan die toenemende geweld. Die Verdrag het die weg gebaan vir die heropbou van staatsinstellings; parlementêre verkiesings in 1992 en 1996; algemene munisipale verkiesings in 1998; die vreedsame oordrag van mag tussen presidente; sowel as die heropbou van die Lebanese ekonomie. Die hoof doel van hierdie studie van Lebanon is om te bepaal of die gewysigde grondwet van 1990 voldoen aan die beginsels van die teoretiese raamwerk rakende grondwetlike uithouvermoë. Die studie is in die vorm van 'n kwalitatiewe gevallestudie. Dit het ten doel om te beskryf en 'n in-diepte begrip van die akteurs en die gebeure wat gelei het tot die Taif Accord, asook die vorming en implementering daarvan te vorm. Die navorsing vrae sluit in: Watter faktore met betrekking tot buigsaamheid, spesifisiteit en insluiting het bygedra tot die verval van die 1943 National Pact?; Watter stappe is geneem wat gelei tot die Taif Verdrag?; en Het die veranderinge in die Lebanese grondwet deur middel van die 1990 Taif Verdrag die langdurigheid van die grandwet gefasiliteer? studie het ten doel om by te dra deur middel van sy toepassing van die teoretiese raamwerk om 'n bepaalde gevallestudie, naamlik dat van die Lebanon. Hierdie studie verskaf ook 'n in-diepte analise van die gebeure in Lebanon oor die afgelope 80 jaar. Die vraag bly staan of die Taif Verdrag se wysigings aan die grondwet voldoende voorsiening gemaak het vir die oorlewing van die grondwet. Twintig jaar van relatiewe vrede het nog nie Lebanese burgers oortuig van die legitimiteit en doeltreffendheid van die Verdrag nie. Alhoewel die oor-sentralisering van mag binne die stelsel ingeperk is deur die verskuiwing van mag weg van die President, na 'n kabinet wat gelykop tussen Christene en Moslems verdeel is, het die Verdrag versuim om effektief met die proporsionele aard van die grondwet te handel. Dit is egter belangrik om op die uniekheid van die Lebanese geval te let, ten spyte van die vele faktore rondom die saak. Hoewel 20 jaar van vrede genoegsaam kan wees om die langdurigheid van 'n grondwet te verseker, speel streeksfaktore, sowel as die teenwoordigheid van radikale groepe 'n belangrike rol in die destabilisering van die fyn balans wat in die land voorkom. Indien die Lebanese staat voortgaan om inklusief en buigsaam te wees in die nasleep van 'n voortdurende, veranderende omgewing, sal dit kan voortleef. Maar die onstuimige aard van die streek waarin Lebanon homself bevind mag eksterne negatiewe faktore na vore bring wat die Lebanese stelsel nie kan hanteer nie. Die hoop is dat hierdie stelsel sal voortbou op sterk, sistemiese fondasies om in staat te wees om eksterne, sowel as interne, konflik te hanteer.