Running from Paris to Beijing: biomechanical and physiological consequences

Abstract The purpose of this study was to examine the physiological and biomechanical changes occurring in a subject after running 8,500 km in 161 days (i.e. 52.8 km daily). Three weeks before, 3 weeks after (POST) and 5 months after (POST?5) running from Paris to Beijing, energy cost of running (Cr), knee flexor and extensor isokinetic strength and biomechanical parameters (using a treadmill dynamometer) at different velocities were assessed in an experienced ultra-runner. At POST, there was a tendency toward a 'smoother' running pattern, as shown by (a) a higher stride frequency and duty factor, and a reduced aerial time without a change in contact time, (b) a lower maximal vertical force and loading rate at impact and (c) a decrease in both potential and kinetic energy changes at each step. This was associated with a detrimental effect on Cr (?6.2%) and a loss of strength at all angular velocities for both knee flexors and extensors. At POST?5, the subject returned to his original running patterns at low but not at high speeds and maximal strength remained reduced at low angular velocities (i.e. at high levels of force). It is suggested that the running pattern changes observed in the present study were a strategy adopted by the subject to reduce the deleterious effects of long distance running. However, the running pattern changes could partly be linked to the decrease in maximal strength

Caractéristiques structurales et fonctionnelles du muscle strié squelettique (effets de l'hémoglobine S et/ou de l'alpha-thalassémie)

De nombreuses études ont mis en évidence le caractère plastique du muscle strié squelettique en réponse à de nombreux stimuli. Ce travail de thèse s est attelé à caractériser les modifications structurales et fonctionnelles potentielles de ce tissu en présence de deux hémoglobinopathies génétiques : la drépanocytose (dans sa forme homozygote et hétérozygote), due à la production d'une hémoglobine anormale (appelée S), et/ou l alpha-thalassémie (dans sa forme hétérozygote, parfois associée à la drépanocytose), se caractérisant par une anémie microcytaire. Les analyses histologiques et biochimiques de prélèvements biopsiques du muscle vastus Iateralis témoignent d un remodelage structural et fonctionnel du muscle et notamment du réseau micro-vasculaire des sujets drépanocytaires. Une raréfaction des micro-vaisseaux, associée à une augmentation de leur diamètre et une diminution de leur tortuosité sont rapportées, adaptations qui pourraient limiter les troubles hémorhéologiques inhérents à l'hémoglobine S. Les activités des enzymes clés du métabolisme oxydatif (CS : citrate synthase et COx : cytochrome c oxydase) ont également été trouvées altérées chez les sujets porteurs de l hémoglobine S. L a-thalassémie fait elle aussi l objet d un léger remodelage micro-vasculaire marqué par une augmentation de la tortuosité des micro-vaisseaux. Enfin, l'association drépanocytose hétérozygote/a-thalassémie, connue pour atténuerles désordres hémorhéologiques et inflammatoires, n engendrerait aucune modification notable descaractéristiques structurales et fonctionnelles du tissu musculaire par rapport à une population contrôle (HbAA)Several studies have demonstrated the skeletal striated muscle plasticity in answer to differentstimuli. The aim of this thesis work was to characterize the structural and functional modifications of this particular tissue face to the sickle cell disease (in both homozygous and heterozygous forms), due to the production of an abnormal hemoglobin (called hemoglobin S), and/or the alpha thalassemia (in her heterozygous form, regularly associated with sickle cell disease). The histochemical and biochemical analysis of the vastus Iateralis biopsy showed evidence for 3 significant structural and functional remodeling of the sickle cell subjects muscle and most particularly of the microvasculature. A reduced capillary density, associated with enlarged microvessels and lower tortuosity are reported, that may possibly limit the hemorheological disorders linked to hemoglobin S. The main oxidative enzymes activities (CS: citrate synthase and COx: cytochrome c oxydase) were also altered in sickle cell subjects. Remodeling of the microvascular network occurs to a lesser extent in a-thalassemia, with an increase of the microvessels tortuosity. Finally, the association of the sickle cell heterozygous form with a-thalassemia, known to reduced hemorheological and inflammatory disorders, does not seem to modify muscle characteristics in comparison to a control population with normal hemoglobinST ETIENNE-Bib. électronique (422189901) / SudocSudocFranceF

Effet d’un exercice d’ultra-endurance sur le muscle squelettique

National audienc

Label-free quantitative protein profiling of the Human muscle during ultra-endurance exercise

National audienc

Non-oxidative Energy Supply Correlates with Lactate Transport and Removal in Trained Rowers

This study aimed to test if the non-oxidative energy supply (estimated by the accumulated oxygen deficit) is associated with an index of muscle lactate accumulation during exercise, muscle monocarboxylate transporter content and the lactate removal ability during recovery in well-trained rowers. Seventeen rowers completed a 3-min all-out exercise on rowing ergometer to estimate the accumulated oxygen deficit. Blood lactate samples were collected during the subsequent passive recovery to assess individual blood lactate curves, which were fitted to the bi-exponential time function: La(t)= [La](0)+A1·(1-e-? 1 t)+A2·(1-e-? 2 t), where the velocity constants ?1 and ?2 (min-1) denote the lactate exchange and removal abilities during recovery, respectively. The accumulated oxygen deficit was correlated with the net amount of lactate released from the previously active muscles (r =0.58,

Protein profiling of the Human muscle during ultra-endurance exercise

National audienc

Modulation of autophagy and ubiquitin-proteasome pathways during ultra-endurance running

In this study, the coordinated activation of ubiquitin-proteasome pathway (UPP), autophagy-lysosomal pathway (ALP), and mitochondrial remodeling including mitophagy was assessed by measuring protein markers during ultra-endurance running exercise in human skeletal muscle. Eleven male, experienced ultra-endurance athletes ran for 24 h on a treadmill. Muscle biopsy samples were taken from the vastus lateralis muscle 2 h before starting and immediately after finishing exercise. Athletes ran 149.8 ± 16.3 km with an effective running time of 18 h 42 min ( ± 41 min). The phosphorylation state of Akt (-74 ± 5%; P < 0.001), FOXO3a (-49 ± 9%; P < 0.001), mTOR Ser2448 (-32 ± 14%; P = 0.028), and 4E-BP1 (-34 ± 7%; P < 0.001) was decreased, whereas AMPK phosphorylation state increased by 247 ± 170% (P = 0.042). Proteasome β2 subunit activity increased by 95 ± 44% (P = 0.028), whereas the activities associated with the β1 and β5 subunits remained unchanged. MuRF1 protein level increased by 55 ± 26% (P = 0.034), whereas MAFbx protein and ubiquitin-conjugated protein levels did not change. LC3bII increased by 554 ± 256% (P = 0.005), and the form of ATG12 conjugated to ATG5 increased by 36 ± 17% (P = 0.042). The mitochondrial fission marker phospho-DRP1 increased by 110 ± 47% (P = 0.003), whereas the fusion marker Mfn1 and the mitophagy markers Parkin and PINK1 remained unchanged. These results fit well with a coordinated regulation of ALP and UPP triggered by FOXO3 and AMPK during ultra-endurance exercise.status: publishe

Vieillissement biologique du muscle squelettique chez l'Homme

Le thème des conférences portera sur : "La mobilité internationale pendant le doctorat"Vieillissement biologique du muscle squelettique chez l'Homme. Journée de la Recherche 2018, Ecole Doctorale Sciences, Ingénierie, Sant

Biological aging of skeletal muscle in humans

Grâce au rassemblement de la communauté de Lyon et de St Etienne, associant chercheurs, cliniciens, étudiants et entreprises, cette première conférence internationale visera à explorer comment et dans quelle mesure l’exercice peut être bénéfique pour les principales cellules de l’appareil locomoteur (muscle, tendon, os, cartilage, vaisseau). Cette journée offrira la possibilité de mettre en avant à la fois des travaux de recherche fondamentale réalisés à un niveau préclinique et des investigations conduites chez le volontaire sain ou sur des cohortes de patients. Des approches cellulaires, moléculaires et fonctionnelles seront mises en avant au cours de cette conférence.Présentation orale et posterAging is characterized by changes in body composition and particularly by a gradual loss of skeletal muscle mass, a phenomenon known as Sarcopenia. This age-related decline in muscle mass is accompanied by a loss of strength and a decline of physical performance, named Dynapenia. Both events decrease the autonomy and the quality of life of the individuals affecting about 40-50% of people over the age of 80. Nonetheless, inter-individual differences in prevalence of sarcopenia/dynapenia exist, as some remain fit and strong, whereas other become frail and weak when they get old. Until now, no study has examined the inter-individual variations of muscle tissue and its biomarkers. At the fiber level, age-related variations in skeletal muscle mass induce typological and capillarization modifications. Furthermore, the loss of muscle mass with aging could be associated with serious metabolic consequences or accumulation of intramyocellular lipid droplets. Immunohistochemical studies were performed with muscle biopsies from 30 healthy elderly men, aged 80 ±0.5 years selected from the PROgnostic indicator of cardiovascular and cerebrovascular events (PROOF) cohort, classified into three groups. On the basis of appendicular mass variation between two DEXA at mean interval of seven years, some people lose more muscle mass, named ”Lost”, others remain ”Stable”, and others ”Gain” muscle mass. The loss of skeletal muscle mass was associated with a reduction in Type-I fibers surface area (-24.6%), accompanied by a proportional loss of capillaries number around each fiber-type (CAF) and capillary-to-fiber perimeter exchange index (CFPE) (-15%, -10% respectively), compared to ”Stable” and ”Gain” groups. Also subjects from the ”Lost” group exhibited significant accumulation of intramyocellular lipid droplets in Type-I fibers compared to the ”Gain” (+23%). Lastly, this decline in muscle mass induced a remodeling of the extracellular matrix with an increase in the endomysium area (+12.2% vs Gain).If usually, it is recognized that chronological aging mainly affects Type-II motor units, our results suggest that biological aging is characterized by impairment of Type-I muscle fibers, their microvascular environment and oxidative metabolism for elderly men on their eighties

How Sickle Cell Disease Impairs Skeletal Muscle Function

International audienc