Symmetric spaces of higher rank do not admit differentiable compactifications

Any nonpositively curved symmetric space admits a topological compactification, namely the Hadamard compactification. For rank one spaces, this topological compactification can be endowed with a differentiable structure such that the action of the isometry group is differentiable. Moreover, the restriction of the action on the boundary leads to a flat model for some geometry (conformal, CR or quaternionic CR depending of the space). One can ask whether such a differentiable compactification exists for higher rank spaces, hopefully leading to some knew geometry to explore. In this paper we answer negatively.Comment: 13 pages, to appear in Mathematische Annale

L'activité physique dans la prise en charge de la mucoviscidose.

National audienc

Etudes des réponses et stratégies ventilatoires en fonction de la modalité d'exercice chez des enfants prépubères sains et des enfants prépubères atteints de mucoviscidose

L'étude des courbes débit/volume d'exercice permet d'étudier la réponse ventilatoire d'un sujet et d'apporter des informations sur l'origine et la sévérité des contraintes mécaniques ventilatoires potentiellement observées au cours de l'exercice. Très peu d'études se sont focalisées sur l'effet d'un exercice sur l'adaptation de la réponse ventilatoire chez l'enfant prépubère à l'aide de cette méthodologie. Or, les caractéristiques du système pulmonaire de l'enfant pourraient induire une adaptation de la réponse ventilatoire à l'exercice spécifique chez l'enfant prépubère par rapport à l'adulte. De plus, l'exposition à une pathologie respiratoire chronique telle que la mucoviscidose pourrait accentuer la spécificité de la réponse ventilatoire à l'exercice chez l'enfant prépubère. Le premier objectif de ce travail de thèse a été d'étudier l'adaptation de la réponse ventilatoire lors d'un exercice incrémental chez des enfants sains et des enfants atteints de mucoviscidose. Nos résultats ont confirmé l'existence d'une spécificité de la réponse ventilatoire chez l'enfant prépubère et l'apparition de contraintes mécaniques ventilatoires lors de l'exercice incrémental, la mucoviscidose n'ayant pas d'effets sur l'adaptation de la réponse ventilatoire à ce type d'exercice. Toutefois, l'exercice incrémental n'est pas représentatif du type d'activité physique réalisé quotidiennement par les enfants. Aussi, le second objectif de ce travail était d'analyser l'effet de la modalité d'exercice: continue vs. intermittente, sur l'adaptation de la réponse ventilatoire. Ceci s'est traduit dans un premier temps par la recherche de correspondances entre les intensités d'exercices continus et intermittents afin de proposer des intensités d'exercices induisant des réponses cardiorespiratoires similaires entre les deux modalités d'exercice. Dans un second temps, nos résultats ont montré l'existence de contraintes mécaniques ventilatoires pour les deux modalités d'exercice, quelque soit l'intensité d'exercice, sans toutefois induire de fatigue des muscles respiratoires. Toutefois, la modalité d'exercice n'aurait aucune influence sur la sévérité de ces contraintes. De plus, comme pour l'exercice incrémental, la présence d'une pathologie respiratoire chronique légère n'influencerait pas l'adaptation de la réponse ventilatoire lors d'exercices continus et intermittents. Les enfants sains ou atteints de mucoviscidose présentent une régulation de la ventilation réalisée de manière prédominante par une augmentation de la fréquence respiratoire.Exercise flow/volume loops allow one to study the ventilatory response of a subject and could bring information on the origin and the severity of mechanical ventilatory constraints potentially observed during exercise. Few studies have focused on the effect of an exercise on the adaptation of ventilatory response in prepubescent children with exercise flow/volume loop methodology. However, the characteristics of the children's pulmonary system could induce a specific adaptation of ventilatory response during exercise in prepubescent children in comparison with the adult. Moreover, the exposition to a chronic respiratory disease like cystic fibrosis could accentuate the specificity of ventilatory response during exercise in prepubescent children. The first aim of this work was to study the adaptation of the ventilatory response during an incremental exercise in healthy children and children with cystic fibrosis. Our results have confirmed the existence of a specific ventilatory response in prepubescent children and the occurrence of mechanical ventilatory constraints during incremental exercise. Cystic fibrosis seems to have no effect on the adaptation of the ventilatory response during incremental exercise. However, incremental exercise was not representative of the physical activity frequently performed by children. The second aim of this work was to determine the effect of the exercise modality: continuous vs. intermittent, on the adaptation of the ventilatory response. Firstly, a search of correspondences between continuous and intermittent exercise intensities was performed in order to propose exercise intensities which induce similar cardio-respiratory responses between the two exercise modalities. Secondly, our results have shown the existence of mechanical ventilatory constraints for both exercise modalities, whatever the exercise intensity. However, the occurrence of mechanical ventilatory constraints does not induce respiratory muscles fatigue. Moreover, the exercise modality seems to have no effect on the severity of the mechanical ventilatory constraints. Finally, as for incremental exercise, mild chronic respiratory disease does not influence the adaptation of the ventilatory response during continuous and intermittent exercises. Children with cystic fibrosis showed similar ventilation regulation whatever the exercise modality, which is predominantly made possible by an increase of breathing frequency.LILLE2-BU Santé-Recherche (593502101) / SudocSudocFranceF

Chapitre 17 : Les maladies respiratoires.

International audienceLa mucoviscidose et l’asthme sont deux pathologies rencontrées chez les enfants et adolescents et qui touchent le système respiratoire. Pendant longtemps, l’activité physique a été déconseillée pour les patients porteurs de ces pathologies car elles étaient susceptibles de mettre en danger leur santé et leur vie. Depuis plusieurs décennies, il a été prouvé qu’au contraire la pratique régulière d’une activité physique permet une amélioration de la condition physique et de la qualité de vie de ces enfants, ainsi que l’acquisition d’une plus grande autonomie. Malgré tout, à notre époque, les réticences et les peurs sont tenaces et de nombreux enfants atteints de pathologies respiratoires continuent de réduire leur activité physique journalière, aidés en cela par leur entourage. La cohésion entre le monde médical, les parents et l’entourage scolaire et sportif des enfants devrait être encouragée. En effet, le manque de connaissances et d’éducation des bienfaits de l’activité physique adaptée à la pathologie ont été jusqu’à présent trop souvent un frein majeur à la prise en charge des enfants concernés.Ce chapitre s’intéressera respectivement à la mucoviscidose et à l’asthme chez l’enfant. Après quelques notions de physiopathologie, et une description des obstacles rencontrés à la pratique d’une activité physique chez ces enfants, nous résumerons les recommandations actuelles d’activité physique pour chacune de ces pathologies, en précisant les précautions à prendre et apportant quelques exemples de pratique

Occupational therapy for improving occupational performance in COPD patients: A scoping review

International audienceBackgroundChronic obstructive pulmonary disease (COPD) is a multisystemic chronic condition which may induce significant consequences in daily life activities. Preserving activities of daily living in COPD is therefore a common treatment goal among people living with COPD, which leaves ample opportunity for occupational therapy interventions to comprise part of their rehabilitation. However, the question of how exactly occupational therapists can and do contribute to pulmonary rehabilitation remains underexplored. Purpose. To reveal the contribution of occupational therapy intervention in the pulmonary rehabilitation on improving the occupational performance of patients with COPD. Method. A scoping review was performed by selecting articles focusing on occupational therapy in pulmonary rehabilitation for patients with COPD. A total of four databases were surveyed for article selection.FindingsAmong nine studies selected, seven studies reported a significant improvement in the occupational performance of patients with occupational therapy. However, two studies did not observe differences between the groups regarding occupational performance. Implications. Occupational therapy in pulmonary rehabilitation seems to contribute to the improvement of occupational performances of patients with COPD. Nevertheless, research focused on this field needs to be further developed to support the positive impact of occupational therapy in COPD management

Responsiveness of Various Exercise-Testing Protocols to Therapeutic Interventions in COPD.

International audienceExercise intolerance is a key element in the pathophysiology and course of Chronic Obstructive Pulmonary Disease (COPD). As such, evaluating exercise tolerance has become an important part of the management of COPD. A wide variety of exercise-testing protocols is currently available, each protocol having its own strengths and weaknesses relative to their discriminative, methodological, and evaluative characteristics. This paper aims to review the responsiveness of several exercise-testing protocols used to evaluate the efficacy of pharmacological and nonpharmacological interventions to improve exercise tolerance in COPD. This will be done taking into account the minimally important difference, an important concept in the interpretation of the findings about responsiveness of exercise testing protocols. Among the currently available exercise-testing protocols (incremental, constant work rate, or self-paced), constant work rate exercise tests (cycle endurance test and endurance shuttle walking test) emerge as the most responsive ones for detecting and quantifying changes in exercise capacity after an intervention in COPD

Comparison Between 30-15 Intermittent Fitness Test and Multistage Field Test on Physiological Responses in Wheelchair Basketball Players

International audienceThe intermittent nature of wheelchair court sports suggests using a similar protocol to assess repeated shuttles and recovery abilities. This study aimed to compare performances, physiological responses and perceived rating exertion obtained from the continuous multistage field test (MFT) and the 30-15 intermittent field test (30-15 IFT). Eighteen trained wheelchair basketball players (WBP) (WBP: 32.0 ± 5.7 y, IWBF classification: 2.9 ± 1.1 points) performed both incremental field tests in randomized order. Time to exhaustion, maximal rolling velocity (MRV), VO 2peak and the peak values of minute ventilation (V Epeak), respiratory frequency (RF) and heart rate (HR peak) were measured throughout both tests; peak and net blood lactate ([Lact − ] = peak–rest values) and perceived rating exertion (RPE) values at the end of each exercise. No significant difference in VO 2peak , VE peak , and RF was found between both tests. 30-15 IFT was shorter (12.4 ± 2.4 vs. 14.9 ± 5.1 min, P < 0.05) but induced higher values of MRV and [Lact − ] compared to MFT (14.2 ± 1.8 vs. 11.1 ± 1.9 km·h −1 and 8.3 ± 4.2 vs. 6.9 3.3 mmol L −1 ± · , P < 0.05). However, HR peak and RPE values were higher during MFT than 30-15 ± ± IFT (172.8 14.0 vs. 166.8 13.8 bpm and 15.3 ± 3.8 vs.13.8 ± 3.5, respectively, P < 0.05). The intermittent shuttles intercepted with rest period occurred during the 30-15 IFT could explain a greater anaerobic solicitation. The higher HR and overall RPE values measured at the end of MFT could be explained by its longer duration and a continuous load stress compared to 30-15 IFT. In conclusion, 30-15 IFT has some advantages over MFT for assess in addition physical fitness and technical performance in WBP

Effects of synchronous versus asynchronous mode of propulsion on wheelchair basketball sprinting.

International audienceThis study aimed to first investigate synchronous (SYN) versus asynchronous (ASY) mode of propulsion and, second, investigate the wheel camber effects on sprinting performance as well as temporal parameters. Seven wheelchair basketball players performed four maximal eight-second sprints on a wheelchair ergometer. They repeated the test according to two modes of propulsion (SYN and ASY) and two wheel cambers (9° and 15°). The mean maximal velocity and push power output was greater in the synchronous mode compared to the asynchronous mode for both camber angles. However, the fluctuation in the velocity profile is inferior for ASY versus SYN mode for both camber angles. Greater push time/cycle time (Pt/Ct) and arm frequency (AF) for synchronous mode versus asynchronous mode and inversely, lesser Ct and rest time (Rt) values for the synchronous mode, for which greater velocity were observed. SYN mode leads to better performance than ASY mode in terms of maximal propulsion velocity. However, ASY propulsion allows greater continuity of the hand-rim force application, reducing fluctuations in the velocity profile. The camber angle had no effect on ASY and SYN mean maximal velocity and push power output. The study of wheelchair propulsion strategies is important for better understanding physiological and biomechanical impacts of wheelchair propulsion for individuals with disabilities. From a kinematical point of view, this study highlights synchronous mode of propulsion to be more efficient, with regards to mean maximal velocity reaching during maximal sprinting exercises. Even if this study focuses on well-trained wheelchair athletes, results from this study could complement the knowledge on the physiological and biomechanical adaptations to wheelchair propulsion and therefore, might be interesting for wheelchair modifications for purposes of rehabilitation

Effects of modified multistage field test on performance and physiological responses in wheelchair basketball players.

International audienceA bioenergetical analysis of manoeuvrability and agility performance for wheelchair players is inexistent. It was aimed at comparing the physiological responses and performance obtained from the octagon multistage field test (MFT) and the modified condition in "8 form" (MFT-8). Sixteen trained wheelchair basketball players performed both tests in randomized condition. The levels performed (end-test score), peak values of oxygen uptake (VO2peak), minute ventilation (VEpeak), heart rate (HRpeak), peak and relative blood lactate (Δ[Lact(-)] = peak - rest values), and the perceived rating exertion (RPE) were measured. MFT-8 induced higher VO2peak and VEpeak values compared to MFT (VO2peak: 2.5 ± 0.6 versus 2.3 ± 0.6 L·min(-1) and VEpeak: 96.3 ± 29.1 versus 86.6 ± 23.4 L·min(-1); P < 0.05) with no difference in other parameters. Significant relations between VEpeak and end-test score were correlated for both field tests (P < 0.05). At exhaustion, MFT attained incompletely VO2peak and VEpeak. Among experienced wheelchair players, MFT-8 had no effect on test performance but generates higher physiological responses than MFT. It could be explained by demands of wheelchair skills occurring in 8 form during the modified condition