Adaptations métaboliques en réponse à l'exercice excentrique dynamique : application au réentrainement.

Chronic pathologies are the world leading cause of death. In addition to reducing functional capacities and degrading patients' life quality, they constitute a major public health expenditure. Part of the management involves appropriate physical activity and exercise training. This aims to improve subjects' capacities, in particular endurance and muscle strength, in order to increase their autonomy and reduce the risk of morbidity and mortality. Classically, endurance cycling or treadmill running exercises are performed at a sub-maximal metabolic intensity (~60%) and in a classic concentric muscle contraction mode. These training conditions, and the associated adaptations, are however limited by the patients' ability to achieve or maintain such stresses over time. It is therefore necessary to develop alternative strategies that take into account cardiac, respiratory and/or muscular limitations linked to the pathology while allowing optimal adaptive responses. One approach is that of dynamic eccentric training through resistance pedaling or downhill running exercises. Compared to concentric mode, eccentric has the ability to generate significant mechanical loads for less cardio-respiratory stress. For several years, the feasibility of this type of training has been observed, including in patients with chronic diseases. Its effectiveness in increasing muscle mass and strength has also been widely demonstrated. Recent work also shows its interest in overweight and obesity management through its effects on body composition and fat reduction. However, aerobic adaptations following eccentric training remain incomplete with regard to initial expectations of improved oxygen uptake and mitochondrial function, for which exercise metabolic intensity appears to be the determining factor. Thus, mixed approaches can be considered in order to develop the best combination that will optimize the overall physical training outcomes by enhancing both muscle strength and endurance.Les pathologies chroniques sont la toute première cause de décès dans le monde. En plus de diminuer considérablement les capacités fonctionnelles des patients et de dégrader leur qualité de vie, elles constituent un poste de dépenses majeures en termes de santé publique. Une partie de la prise en charge de ces pathologies passe par l’activité physique adaptée et la mise en place d’un réentrainement à l’effort. Celui-ci vise à améliorer les capacités des sujets, notamment les capacités d’endurance et de force musculaire, afin de gagner en autonomie et diminuer les risques de morbi-mortalité. Classiquement, les exercices d’endurance de pédalage ou de course sur tapis roulant sont réalisés à une intensité métabolique sous maximale (~60 %) et en mode de contraction musculaire concentrique. Ces conditions de réentrainement et les adaptations associées sont cependant limitées par la capacité des patients à atteindre ou à maintenir dans le temps de telles sollicitations. Il est donc nécessaire de mettre au point des stratégies d’entrainement alternatives prenant en considération la problématique de limitations cardiaque, respiratoire et/ou musculaire liées à la pathologie tout en permettant la mise en place de réponses adaptatives optimales. L’une des pistes est celle de l’entrainement excentrique dynamique au travers d’exercices de pédalage en résistance ou de course en descente. Comparativement à la modalité concentrique, l’excentrique à la capacité de générer des charges mécaniques importantes pour une sollicitation cardio-respiratoire moindre. Depuis plusieurs années, la faisabilité de ce type d’entrainement a été observée, y compris auprès de patients atteints de maladies chroniques. Son efficacité dans la prise de masse musculaire et le gain de force a aussi largement été démontrée. De récents travaux montrent également son intérêt dans la gestion du surpoids et de l’obésité grâce à ses effets sur la composition corporelle via de la réduction de masse grasse. Toutefois, les adaptations aérobies suite à un entrainement excentrique restent incomplètes aux regards des attentes initiales d’amélioration de la consommation d’oxygène et de la fonctionnalité mitochondriale, pour lesquelles l’intensité métabolique de l’exercice semble être le facteur déterminant. Ainsi, des approches mixtes peuvent être envisagées afin de développer les meilleures combinaisons qui permettront d’optimiser les résultats globaux de l’entrainement en améliorant à la fois la force musculaire et l’endurance

Metabolic adaptations in response to dynamic eccentric exercise : application to rehabilitation

Les pathologies chroniques sont la toute première cause de décès dans le monde. En plus de diminuer considérablement les capacités fonctionnelles des patients et de dégrader leur qualité de vie, elles constituent un poste de dépenses majeures en termes de santé publique. Une partie de la prise en charge de ces pathologies passe par l’activité physique adaptée et la mise en place d’un réentrainement à l’effort. Celui-ci vise à améliorer les capacités des sujets, notamment les capacités d’endurance et de force musculaire, afin de gagner en autonomie et diminuer les risques de morbi-mortalité. Classiquement, les exercices d’endurance de pédalage ou de course sur tapis roulant sont réalisés à une intensité métabolique sous maximale (~60 %) et en mode de contraction musculaire concentrique. Ces conditions de réentrainement et les adaptations associées sont cependant limitées par la capacité des patients à atteindre ou à maintenir dans le temps de telles sollicitations. Il est donc nécessaire de mettre au point des stratégies d’entrainement alternatives prenant en considération la problématique de limitations cardiaque, respiratoire et/ou musculaire liées à la pathologie tout en permettant la mise en place de réponses adaptatives optimales. L’une des pistes est celle de l’entrainement excentrique dynamique au travers d’exercices de pédalage en résistance ou de course en descente. Comparativement à la modalité concentrique, l’excentrique à la capacité de générer des charges mécaniques importantes pour une sollicitation cardio-respiratoire moindre. Depuis plusieurs années, la faisabilité de ce type d’entrainement a été observée, y compris auprès de patients atteints de maladies chroniques. Son efficacité dans la prise de masse musculaire et le gain de force a aussi largement été démontrée. De récents travaux montrent également son intérêt dans la gestion du surpoids et de l’obésité grâce à ses effets sur la composition corporelle via de la réduction de masse grasse. Toutefois, les adaptations aérobies suite à un entrainement excentrique restent incomplètes aux regards des attentes initiales d’amélioration de la consommation d’oxygène et de la fonctionnalité mitochondriale, pour lesquelles l’intensité métabolique de l’exercice semble être le facteur déterminant. Ainsi, des approches mixtes peuvent être envisagées afin de développer les meilleures combinaisons qui permettront d’optimiser les résultats globaux de l’entrainement en améliorant à la fois la force musculaire et l’endurance.Chronic pathologies are the world leading cause of death. In addition to reducing functional capacities and degrading patients' life quality, they constitute a major public health expenditure. Part of the management involves appropriate physical activity and exercise training. This aims to improve subjects' capacities, in particular endurance and muscle strength, in order to increase their autonomy and reduce the risk of morbidity and mortality. Classically, endurance cycling or treadmill running exercises are performed at a sub-maximal metabolic intensity (~60%) and in a classic concentric muscle contraction mode. These training conditions, and the associated adaptations, are however limited by the patients' ability to achieve or maintain such stresses over time. It is therefore necessary to develop alternative strategies that take into account cardiac, respiratory and/or muscular limitations linked to the pathology while allowing optimal adaptive responses. One approach is that of dynamic eccentric training through resistance pedaling or downhill running exercises. Compared to concentric mode, eccentric has the ability to generate significant mechanical loads for less cardio-respiratory stress. For several years, the feasibility of this type of training has been observed, including in patients with chronic diseases. Its effectiveness in increasing muscle mass and strength has also been widely demonstrated. Recent work also shows its interest in overweight and obesity management through its effects on body composition and fat reduction. However, aerobic adaptations following eccentric training remain incomplete with regard to initial expectations of improved oxygen uptake and mitochondrial function, for which exercise metabolic intensity appears to be the determining factor. Thus, mixed approaches can be considered in order to develop the best combination that will optimize the overall physical training outcomes by enhancing both muscle strength and endurance

Impact of downhill running on body composition and energy expenditure

Poster session 1We aimed to compare the effects of 8-week eccentric versus concentric exercise training in rats on body composition and energy expenditure, since these parameters have not been fully investigated. Animals were assigned to group 1) control, 2) +15% uphill-running slope (CON), 3) -15% downhill- running slope (ECC15, iso-power output) or 4) -30% downhill-running slope (ECC30, iso-VO2). Total body mass increased in all groups over the 8 weeks. A significant gain in fat mass was only observed for control group (20.71±1.99g) compared to CON (-4.8±6.18g); ECC15 (0.6±3.32g) and ECC30 (2.6±6.01g). A gain in lean mass was mainly seen for ECC15 (88.9±6.85g, p=0.09) and ECC30 (101.6±11.07g, p=0.02). Basal metabolic rate increased for all running groups. Thereby, the impact of training on lean mass is enhanced with ECC30 compared to CON, and adaptations are still observed for lower VO2 (ECC15). Thus low intensity eccentric exercise training could be part of body composition regulation strategies

Eccentric and concentric exercises induce different adaptions in adipose tissue biology

International audienceAlterations in adipose tissue (AT) metabolism related to inflammation and adipokine's production lead to perturbations in its capacity to store lipids and release fatty acids (FA) during feeding/fasting transition or during exercise. Exercise has a beneficial effect on AT metabolism, but conventional trainings are not always suitable for patients with functional limitations. Dynamic eccentric (ECC) exercise prevents the accumulation of AT and may then overcome those limitations. Consequently, this study aimed at investigating AT's adaptations after ECC training. Nine-week-old male rats were randomly assigned to a control sedentary or three-trained groups for which treadmill slopes modulated exercise oxygen consumption (VO2) and mechanical work (n = 15 per group): (1) + 15% uphill-concentric group (CONC), (2) - 15% downhill group (ECC15, same mechanical work as CONC) and (3) - 30% downhill group (ECC30, same VO2, or oxygen cost as CONC). Body composition and energy expenditure (EE) were measured before and after 8 weeks of training. Subcutaneous AT was collected to study total FA profile and gene expression. Higher total EE was driven by lean mass gain in trained animals. In AT, there was a decrease in arachidonic acid with CONC or ECC15 training. Increased adiponectin, leptin, lipases, Glut4 and Igf1 mRNA levels in ECC15 group suggested major metabolic adaption in AT. In conclusion, ECC could induce beneficial modifications in AT fatty acid profile and the expression of key genes related to metabolism and insulin sensitivity

Eccentric Training Improves Body Composition by Inducing Mechanical and Metabolic Adaptations: A Promising Approach for Overweight and Obese Individuals

Eccentric Training Improves Body Composition by Inducing Mechanical and Metabolic Adaptations: A Promising Approach for Overweight and Obese Individual

Dietary Cocoa Flavanols Enhance Mitochondrial Function in Skeletal Muscle and Modify Whole-Body Metabolism in Healthy Mice

International audienceMitochondrial dysfunction is widely reported in various diseases and contributes to their pathogenesis. We assessed the effect of cocoa flavanols supplementation on mitochondrial function and whole metabolism, and we explored whether the mitochondrial deacetylase sirtuin-3 (Sirt3) is involved or not. We explored the effects of 15 days of CF supplementation in wild type and Sirt3-/- mice. Whole-body metabolism was assessed by indirect calorimetry, and an oral glucose tolerance test was performed to assess glucose metabolism. Mitochondrial respiratory function was assessed in permeabilised fibres and the pyridine nucleotides content (NAD+ and NADH) were quantified. In the wild type, CF supplementation significantly modified whole-body metabolism by promoting carbohydrate use and improved glucose tolerance. CF supplementation induced a significant increase of mitochondrial mass, while significant qualitative adaptation occurred to maintain H2O2 production and cellular oxidative stress. CF supplementation induced a significant increase in NAD+ and NADH content. All the effects mentioned above were blunted in Sirt3-/- mice. Collectively, CF supplementation boosted the NAD metabolism that stimulates sirtuins metabolism and improved mitochondrial function, which likely contributed to the observed whole-body metabolism adaptation, with a greater ability to use carbohydrates, at least partially through Sirt3