A new stochastic process to model Heart Rate series during exhaustive run and an estimator of its fractality parameter

International audienceIn order to interpret and explain the physiological signal behaviors, it can be interesting to find some constants among the fluctuations of these data during all the effort or during different stages of the race (which can be detected using a change points detection method). Several recent papers have proposed the long-range dependence (Hurst) parameter as such a constant. However, their results induce two main problems. Firstly, DFA method is usually applied for estimating this parameter. Clearly, such a method does not provide the most efficient estimator and moreover it is not at all robust even in the case of smooth trends. Secondly, this method often gives estimated Hurst parameters larger than $1$, which is the larger possible value for long memory stationary processes. In this article we propose solutions for both these problems and we define a new model allowing such estimated parameters

Cardiac Output and Performance during a Marathon Race in Middle-Aged Recreational Runners

Purpose. Despite the increasing popularity of marathon running, there are no data on the responses of stroke volume (SV) and cardiac output (CO) to exercise in this context. We sought to establish whether marathon performance is associated with the ability to sustain high fractional use of maximal SV and CO (i.e, cardiac endurance) and/or CO, per meter (i.e., cardiac cost). Methods. We measured the SV, heart rate (HR), CO, and running speed of 14 recreational runners in an incremental, maximal laboratory test and then during a real marathon race (mean performance: 3 hr 30 min ± 45 min). Results. Our data revealed that HR, SV and CO were all in a high but submaximal steady state during the marathon (87.0 ± 1.6%, 77.2 ± 2.6%, and 68.7 ± 2.8% of maximal values, respectively). Marathon performance was inversely correlated with an upward drift in the CO/speed ratio (mL of CO × m−1) (r = −0.65, P < 0.01) and positively correlated with the runner's ability to complete the race at a high percentage of the speed at maximal SV (r = 0.83, P < 0.0002). Conclusion. Our results showed that marathon performance is inversely correlated with cardiac cost and positively correlated with cardiac endurance. The CO response could be a benchmark for race performance in recreational marathon runners

Protein catabolism and high lipid metabolism associated with long-distance exercise are revealed by plasma NMR metabolomics in endurance horses.

International audienceDuring long distance endurance races, horses undergo high physiological and metabolic stresses. The adaptation processes involve the modulation of the energetic pathways in order to meet the energy demand. The aims were to evaluate the effects of long endurance exercise on the plasma metabolomic profiles and to investigate the relationships with the individual horse performances. The metabolomic profiles of the horses were analyzed using the non-dedicated methodology, NMR spectroscopy and statistical multivariate analysis. The advantage of this method is to investigate several metabolomic pathways at the same time in a single sample. The plasmas were obtained before exercise (BE) and post exercise (PE) from 69 horses competing in three endurance races at national level (130-160 km). Biochemical assays were also performed on the samples taken at PE. The proton NMR spectra were compared using the supervised orthogonal projection on latent structure method according to several factors. Among these factors, the race location was not significant whereas the effect of the race exercise (sample BE vs PE of same horse) was highly discriminating. This result was confirmed by the projection of unpaired samples (only BE or PE sample of different horses). The metabolomic profiles proved that protein, energetic and lipid metabolisms as well as glycoproteins content are highly affected by the long endurance exercise. The BE samples from finisher horses could be discriminated according to the racing speed based on their metabolomic lipid content. The PE samples could be discriminated according to the horse ranking position at the end of the race with lactate as unique correlated metabolite. As a conclusion, the metabolomic profiles of plasmas taken before and after the race provided a better understanding of the high energy demand and protein catabolism pathway that could expose the horses to metabolic disorders

Effets de la fatigue et du niveau d'entraînement : étude des relations entre les coûts énerfétique et mécanique en course à pied

La performance en course d'endurance dépend à la fois des qualité énergétiques et mécaniques du coureur. En effet, le temps mis pour parcourir une distance donnée est fonction du travail mécanique réalisé par les muscles et de l'énergie consommée pour produire ce travail. Au cours du XXème siècle, de nombreux travaux ont mesuré la relation entre le coût mécanique et le coût énergétique de la locomotion. L'étude de cette relation pose de nombreux problèmes d'ordre méthodologique car la mesure du coût mécanique résulte d'une évaluation globale des changements dans les niveaux d'énergie mécanique. L'énergie réellement développée par chaque muscle reste inconnue. Pour contourner ces difficultés méthodologiques, notre approche consiste à mesurer les effets de la modification du coût énergétique sur le coût mécanique, ou inversement. Ce travail a permis de mesurer les effets de la fatigue et du niveau d'entraînement sur les différents composants du coût mécanique (les coûts mécaniques potentiel, cinétique et de gesticulation : Cpot, Ccin, et Cgest) et sur le coût énergétique (C). L'analyse des principaux résultats montre d'une part, que la modification du C induite par la fatigue n'est pas liée à une modification du coût mécanique et d'autre part, que la modification des différentes composantes du coût mécanique suivant le niveau d'entraînement n'est pas en relation avec une amélioration du C. Les modifications des paramètres mécaniques avec la fatigue ou le niveau d'entraînement ne sont donc pas associées à des modification du C. La performance en endureance paraît donc dépendres à la fois de paramères énergétiques et de paramètres mécaniques tels que la variabilités de la fréquence de pas, le déplacement vertical du centre de masse, ou le coût mécanique de gesticulation. Néanmoins, les résultats obtenus dans ce travail ne permettant pas de préciser avec certitude les mécanismes responsables des modifications du coût mécanique, deux hypothèses peuvent être formulées. Les modifications biomécaniques observées pourraient être associées à des modifications des propriétés élastiques des muscles et des tendons, ou à un mécanisme visant à diminuer le choc induit par la pose du pied au sol.EVRY-BU (912282101) / SudocSudocFranceF

Perceived exertion scales attest to both intensity and exercise duration.

The SNP rs167771 of the dopamine-3-receptor gene (DRD3) has been associated with autism spectrum disorder (ASD) in samples from the United Kingdom, The Netherlands and Spain. The DRD3 polymorphisms of rs167771 are significantly associated with a specific type of repetitive and stereotyped behavior, called sameness. Repetitive and stereotyped behavior occurs in several neuropsychiatric disorders and the combined picture across these disorders strongly suggests the involvement of the basal ganglia - frontal lobe circuitry. In autism, abnormalities of the basal ganglia, in particular the caudate nucleus, are the best replicated findings in neuroimaging studies. Interestingly, the DRD3 gene is highly expressed in the basal ganglia, most notably the caudate nucleus. The rs167771 SNP was recently also found to be related to risperidone-induced extra-pyramidal side effects (EPS) in patients with autism, which is important since risperidone is approved for the treatment of aggression, irritability and rigid behavior in ASD. To conclude, striatum abnormalities in autism are associated with repetitive and stereotyped behavior in autism and may be related to DRD3 polymorphisms

Consommation d'oxygène et performance en natation (effet de l'intensité, de la modalité de l'exercice et de l'entraînement)

Les travaux en course à pied ont montré que l étude de la réponse de la consommation d oxygène ( O2) par l analyse de la cinétique de O2 apportait de nombreuses connaissances sur le métabolisme aérobie et permettait d améliorer les concepts d entraînement. En natation, si le métabolisme aérobie a souvent été étudié, l étude de la réponse de la O2 pendant la nage en est à ses débuts et devient un nouveau point d intérêt pour la recherche et l entraînement. Le but de cette thèse fut donc l étude de l effet de l intensité, de la modalité de l exercice et de l entraînement sur la réponse de O2 pendant la nage et la performance. Nos résultats ont montré que la cinétique de O2 est accélérée avec l intensité de nage, et est sensible à l entraînement et au contrôle de la fréquence de bras ou de la vitesse de nage. Ces résultats ont pour but de dégager de nouvelles connaissances sur le métabolisme aérobie pendant la nage ainsi que des perspectives pour l entraînement.Publications in running showed that the study of the oxygen uptake ( O2) response by the analyse of the O2 kinetics brought knowledge on aerobic metabolism and allowed to improve training concepts. In swimming, aerobic metabolism was often studied. However, analyse of O2 response during swimming is at the beginning and presents a new point of interest for research and training. Thus, the aim of this thesis was to examine the effect of intensity, exercise modality and training on O2 response during swimming and performance. Our results showed that O2 kinetics is accelerated with swimming intensity, and is sensible to the training and the control of stroke rate or velocity. These results allow to bring out new knowledge on aerobic metabolism during swimming and new perspective for training.EVRY-Bib. électronique (912289901) / SudocSudocFranceF