Search

In healthy subjects, at low minute ventilation (V_ E) during physical exercise, the water content and temperature of the airways are well regulated. However, with the increase in V_ E, the bronchial mucosa becomes dehydrated and epithelial damage occurs. Our goal was to demonstrate the correspondence between the ventilatory threshold inducing epithelial damage, measured experimentally, and the dehydration threshold, estimated numerically. In 16 healthy adults, we assessed epithelial damage before and following a 30-min continuous cycling exercise at 70% of maximal work rate, by measuring the variation pre- to postexercise of serum club cell protein (cc16/cr). Blood samples were collected at rest, just at the end of the standardized 10 min warm-up, and immediately, 30 min and 60 min postexercise. Mean V_ E during exercise was kept for analysis. Airway water and heat losses were estimated using a computational model adapted to the experimental conditions and were compared with a literature-based threshold of bronchial dehydration. Eleven participants exceeded the threshold for bronchial dehydration during exercise (group A) and five did not (group B). Compared with post warm-up, the increase in cc16/cr postexercise was significant (mean increase ± SE: 0.48 ± 0.08 ng·L 1 only in group A but not in group B (mean difference ± SE: 0.10 ± 0.04 ng·L 1). This corresponds to an increase of 101 ± 32% [range: 16%–367%] in group A (mean ± SE). Our findings suggest that the use of a computational model may be helpful to estimate an individual dehydration threshold of the airways that is associated with epithelial damage during physical exercise. 132;4

Purpose:This study examined the effects of a five-week intervention combining vigorous interval training (VIT) with diet among twenty-four obese adolescents. Fourteen girls and ten boys (aged 14–15) schooled in a pediatric rehabilitation center participated. Methods:The VIT intensity was targeted and remained above 80% of maximal heart rate (HR) and over six kilocalories per minute. Pre- and postintervention measures were body composition (BMI, weight, body fat percentage), physical self-perceptions (PSP), physical fitness (6-min walking distance and work) and its associated physiological responses (HRpeak and blood lactate concentration). A series of two-way analyses of variance or covariance controlling for weight loss were used to examine the changes. Results:Significant improvements were found in body composition, physical fitness and PSP (endurance, activity level, sport competence, global physical self-concept and appearance). In addition, boys presented higher levels of perceived strength and global physical self-concept than girls. Finally, there was a significant increase in perceived endurance, sport competence, and global physical self-concept in girls only. Conclusion:This five-week VIT program combined with diet represents an effective means for improving body composition, physical fitness, and PSP in obese adolescents, the effects on PSP being larger among girls.

The health benefits of physical activity (PA) are acknowledged and promoted by the scientific community, especially within primary care. However, there is little evidence that such promotion is provided in any consistent or comprehensive format. Brief interventions (i.e. discussion, negotiation or encouragement) and exercise referral schemes (i.e. patients being formally referred to a PA professional) are the two dominant approaches within primary care. These cost-effective interventions can generate positive changes in health outcomes and PA levels in inactive patients who are at increased risk for non-communicable diseases. Their success relies on the acceptability and efficiency of primary care professionals to deliver PA counselling. To this end, appropriate training and financial support are crucial. Similarly, human resourcing and synergy between the different stakeholders must be addressed. To obtain maximum adherence, specific populations should be targeted and interventions adapted to their needs. Key enablers include motivational interviewing, social support and multi-disciplinary approaches. Leadership and lines of accountability must be clearly delineated to ensure the success of the initiatives promoting PA in primary care. The synergic and multisectoral action of several stakeholders, especially healthcare professionals, will help overcome physical inactivity in a sustainable way.

The purpose of this study was to identify the influence of different magnitudes and directions of the vibration platform acceleration on surface electromyography (sEMG) during whole-body vibration (WBV) exercises. Therefore, a WBV platform was used that delivers vertical vibrations by a side-alternating mode, horizontal vibrations by a circular mode, and vibrations in all 3 planes by a dual mode. Surface electromyography signals of selected lower limb muscles were measured in 30 individuals while they performed a static squat on a vibration platform. The WBV trials included 2 side-alternating trials (Side-L: 6 Hz, 2.5 mm; Side-H: 16 Hz, 4 mm), 2 circular trials (Circ-L: 14 Hz, 0.8 mm; Circ-H: 43 Hz, 0.8 mm), and 4 dual-mode trials that were the combinations of the single-mode trials (Side-L/Circ-L, Side-L/Circ-H, Side-H/Circ-L, Side-H/Circ-H). Furthermore, control trials without vibration were assessed, and 3-dimensional platform acceleration was quantified during the vibration. Significant increases in the root mean square of the sEMG (sEMGRMS) compared with the control trial were found in most muscles for Side-L/Circ-H (+17 to +63%, p ≤ 0.05), Side-H/Circ-L (+7 to +227%, p ≤ 0.05), and Side-H/Circ-H (+21 to +207%, p < 0.01) and in the lower leg muscles for Side-H (+35 to +138%, p ≤ 0.05). Furthermore, only the vertical platform acceleration showed a linear relationship (r = 0.970, p < 0.001) with the averaged sEMGRMS of the lower limb muscles. Significant increases in sEMGRMS were found with a vertical acceleration threshold of 18 m·s(-2) and higher. The present results emphasize that WBV exercises should be performed on a platform that induces vertical accelerations of 18 m·s(-2) and higher.

Background Health effects of sedentary behaviors (SB) may vary depending on their characteristics such as type, purpose, duration, and intensity of the behavior. While a growing number of questionnaires assess sedentary behaviors, it is unclear which characteristics of SB are measured. The aim of this review was to examine the content of self-report SB questionnaires. Methods Three databases were searched for sedentary behavior questionnaires published before January 1st, 2016. Based on the inclusion criteria, 82 articles out of 1369 were retrieved for a total of 60 questionnaires. For each questionnaire, the sedentary behavior characteristics identified were reported and analyzed. Results Most of the questionnaires assessed the time (n = 60), posture (n = 54), purpose (n = 46) and the types (n = 45) of SB performed. Fewer questionnaires assessed the environment (n = 20) social context (n = 11), status (n = 2), and associated behaviors (n = 2) related to sedentary behaviors. All the questionnaires except two assessed time spent in SB with 17 assessing frequency and 6 assessing breaks in SB. The most frequent characteristics identified in the questionnaires were the categories of sitting (90%), a day (95%), watching television (65%) and using a computer (55%). Many characteristics of SB were not measured. Conclusions By knowing the breadth of SB included in questionnaires, this review provides support to shape the design of new questionnaires designed to reduce the gaps in measuring sedentary behaviors.

The present work aimed to determine the influence of exercise duration and endurance training level on the mechanisms underlying neuromuscular fatigue regulation and the effect of a deceptive strategy on exercise performance. This thesis also aimed to elaborate a new training method that would optimize exercise-induced training stimuli that are known to trigger complementary physical abilities adaptations. The main outcomes of these works are detailed in an expanded abstract at the end of the manuscript.; Ce travail de thèse visait à déterminer l’influence de la durée et du niveau d’entraînement en endurance sur les mécanismes de régulation de la fatigue neuromusculaire et d’une stratégie de modulation de ces mécanismes sur la performance motrice. Ce travail de thèse consistait également à élaborer une nouvelle méthode d’entraînement permettant d’optimiser les stimuli responsables des adaptations résultantes d’un programme de conditionnement physique. Les résultats principaux issus de ces travaux sont présentés dans un résumé plus détaillé en fin de manuscrit.

International audience; The purpose of this study was to compare lower limb muscle activity between physically active and inactive individuals during whole-body vibration exercises. Additionally, transmissibility of the vertical acceleration to the head was quantified. 30 active and 28 inactive participants volunteered to stand in a relaxed (20°) and a squat (60°) position on a side-alternating WBV platform that induced vibrations at 16 Hz and 4 mm amplitude. Surface electromyography (sEMG) was measured in selected lower limb muscles and was normalized to the corresponding sEMG recorded during a maximal voluntary contraction. The vertical acceleration on the head was evaluated and divided by the vertical platform acceleration to obtain transmissibility values. Control trials without vibration were also assessed. The outcomes of this study showed that (1) WBV significantly increased muscle activity in the active (absolute increase: +7%, P 0.05). However, (3), transmissibility to the head was greater in the active (0.080) than the inactive participants (0.065, P

Background and Purpose— This study was designed to compare the effects of high-intensity interval training (HIT) and moderate-intensity aerobic training (MOD) on functional recovery and cerebral plasticity during the first 2 weeks after cerebral ischemia. Methods— Rats were randomized as follows: control (n=15), SHAM (n=9), middle cerebral artery occlusion (n=13), middle cerebral artery occlusion at day 1 (n=7), MOD (n=13), and HIT (n=13). Incremental tests were performed at day 1 (D1) and 14 (D14) to identify the running speed associated with the lactate threshold ( S LT ) and the maximal speed ( S max ). Functional tests were performed at D1, D7, and D14. Microglia form, cytokines, p75 NTR (pan-neurotrophin receptor p75), potassium–chloride cotransporter type 2, and sodium–potassium–chloride cotransporter type 1 expression were made at D15. Results— HIT was more effective to improve the endurance performance than MOD and induced a fast recovery of the impaired forelimb grip force. The ionized calcium binding adaptor molecule 1 (Iba-1)–positive cells with amoeboid form and the pro- and anti-inflammatory cytokine expression were lower in HIT group, mainly in the ipsilesional hemisphere. A p75 NTR overexpression is observed on the ipsilesional side together with a restored sodium–potassium–chloride cotransporter type 1/potassium–chloride cotransporter type 2 ratio on the contralesional side. Conclusions— Low-volume HIT based on lactate threshold seems to be more effective after cerebral ischemia than work-matched MOD to improve aerobic fitness and grip strength and might promote cerebral plasticity.

While effects of the two classes of proteins found in milk (i.e., soluble proteins, including whey, and casein) on muscle protein synthesis have been well investigated after a single bout of resistance exercise (RE), the combined effects of these two proteins on the muscle responses to resistance training (RT) have not yet been investigated. Therefore, the aim of this study was to examine the effects of protein supplementation varying by the ratio between milk soluble proteins (fast-digested protein) and casein (slow-digested protein) on the muscle to a 9-week RT program. In a double-blind protocol, 31 resistance-trained men, were assigned to 3 groups receiving a drink containing 20g of protein comprising either 100% of fast protein (FP(100), n = 10), 50% of fast and 50% of slow proteins (FP(50), n = 11) or 20% of fast protein and 80% of casein (FP(20), n = 10) at the end of training bouts. Body composition (DXA), and maximal strength in dynamic and isometric were analyzed before and after RT. Moreover, blood plasma aminoacidemia kinetic after RE was measured. The results showed a higher leucine bioavailability after ingestion of FP(100) and FP(50) drinks, when compared with FP(20) (p< .05). However, the RT-induced changes in lean body mass (p < .01), dynamic (p < .01), and isometric muscle strength (p < .05) increased similarly in all experimental groups. To conclude, compared with the FP(20) group, the higher rise in plasma amino acids following the ingestion of FP(100) and FP(50) did not lead to higher muscle long-term adaptations.

Stroke is a major public health issue because associated functional disorders have detrimental impacts on life quality and independence of patients as well as on economic state. This thesis work is focused on 2-research axis concerning cerebral ischemia in rat. The aim of the first axis is to study plasticity at spinal level by investigating the alteration of somatic reflex regulation that could contribute to partially explain functional deficits. Ours results show early fatigue of triceps brachii during an isometric contraction and H-reflex inhibition perturbation post-exercise. We also observed that the disturbance of reflex pathway activity is associated with a decrease of the inhibitory effect induced by muscular metabosensitive afferents that might explain early fatigue and observed functional deficits. The second axis treats about endurance training that is a promising strategy to reduce stroke-induced disorders but remains to improve. In that way, the purpose is to determine which endurance strategy is the most suitable by focusing on exercise intensity. In order to ensure this, the effects of moderate intensity exercise (classically recommended) have been compared to high intensity interval training (HIT) by analysing the functional recovery and cerebral neuroplasticity. Our data show that work intensity, based on lactic threshold, is a critical parameter. Indeed, HIT is more effective for increasing grip strength recovery, aerobic capacity as well as promoting neuroplasticity. The results of these 2 lines of research could be now associated by deepening the HIT effects at cerebral and spinal level that lead to numerous perspectives.; L’accident vasculaire cérébral (AVC) est un problème majeur de santé publique car les troubles fonctionnels associés ont des répercussions délétères sur la qualité de vie des patients. Deux axes de recherche portant sur l’ischémie cérébrale chez le rat sont abordés. Pour le premier, il s’agira d’étudier les modifications de la régulation des réflexes somatiques qui peuvent contribuer à expliquer en partie les déficits fonctionnels. Nos résultats montrent une fatigue précoce au cours d’un exercice isométrique du triceps brachial et une perturbation de l’inhibition du réflexe-H post-exercice. Nous avons précisé que la perturbation de l’activité des voies réflexes est associée à une modification de l’action inhibitrice des afférences musculaires des groupes III et IV pouvant expliquer la fatigue précoce observée. L’axe 2 concerne l’optimisation de l’entrainement d’endurance, stratégie prometteuse pour traiter les déficits. L’objectif est de définir la stratégie d’endurance la plus appropriée en nous focalisant sur l’intensité de l’exercice. Pour cela, les effets des exercices d’intensité modérée (classiquement recommandés) ont été confrontés avec ceux des exercices intermittents de haute intensité (HIT) en analysant la récupération fonctionnelle et la neuroplasticité cérébrale. Nos résultats montrent que l’intensité de travail, déterminée à partir du seuil lactique, est un paramètre crucial car les HIT se révèlent être plus efficaces en termes de récupération de la force, d’aptitude aérobie et de neuroplasticité. Ces travaux ouvrent de nombreuses perspectives où ces 2 axes pourraient se rejoindre en approfondissant les effets des HIT au niveau cérébral et spinal.

PURPOSE This study aimed to investigate the effect of different magnitudes of deception on performance and exercise-induced fatigue during cycling time trial. METHODS After three familiarization visits, three women and eight men performed three 5-km cycling time trials while following a simulated dynamic avatar reproducing either 100% (5K100%), 102% (5K102%), or 105% (5K105%) of the subject's previous fastest trial. Quadriceps muscle activation was quantified with surface electromyography. Fatigue was quantified by preexercise to postexercise (10 s through 15 min recovery) changes in quadriceps maximal voluntary contraction (MVC) force, potentiated twitch force evoked by electrical femoral nerve stimulation (QTSingle) and voluntary activation (VA, twitch interpolation technique). RESULTS Greater quadriceps muscle activation in 5K102% versus 5K100% (12% ± 11%) was found in parallel with a 5% ± 2% and 2% ± 1% improvement in power output and completion time, respectively (P < 0.01). Exercise-induced reduction in MVC force and VA were 14% ± 19% and 28% ± 31% greater at exercise termination (at 10 s), whereas QTSingle recovery (from 10 s to 15 min) was 5% ± 5% less in 5K102% versus 5K100% (P < 0.01). No difference in performance or fatigue indices measured at exercise termination was found between 5K100% and 5K105%. CONCLUSIONS Muscle activation and performance improvements during a deceptive cycling time trial were achieved only with a 2% magnitude of deception and were associated with a further impairment in MVC force, QTSingle recovery and VA compared to control. Performance improvement during cycling time trial with augmented deceptive feedback therefore resulted in exacerbated exercise-induced peripheral and central fatigue.

International audience; This study aims to examine the repeated effects of three sessions of vigorous interval training (VIT) in basketball, running-biking, and boxing on the physical self-perceptions (PSP) of obese adolescents participating in a dietary program. A sample of 24 obese adolescents performed the consecutive VIT sessions every week for 5 weeks. PSP were measured immediately after each training session. Analyses of covariance were used to examine changes in PSP. The results showed rapid and constant increases in PSP with significant differences according to sex, time, type of VIT, and an interaction of sex by time by type of VIT, mainly for basketball.

International audience; The acute-exercise effects upon cognitive functions are varied and dependent upon exercise duration and intensity, and the type of cognitive tasks assessed. The hypofrontality hypothesis assumes that prolonged exercise, at physiologically challenging intensities, is detrimental to executive functions due to cerebral perturbations (indicated by reduced prefrontal activity). The present study aimed to test this hypothesis by measuring oxygenation in prefrontal and motor regions using near-infrared spectroscopy during two executive tasks (flanker task and 2-back task) performed while cycling for 60 min at a very low intensity and an intensity above the ventilatory threshold. Findings revealed that, compared to very low intensity, physiologically challenging exercise (i) shortened reaction time in the flanker task, (ii) impaired performance in the 2-back task, and (iii) initially increased oxygenation in prefrontal, but not motor regions, which then became stable in both regions over time. Therefore, during prolonged exercise, not only is the intensity of exercise assessed important, but also the nature of the cognitive processes involved in the task. In contrast to the hypofrontality hypothesis, no inverse pattern of oxygenation between prefrontal and motor regions was observed, and prefrontal oxygenation was maintained over time. The present results go against the hypofrontality hypothesis. (C) 2017 Elsevier Inc. All rights reserved.

Purpose:To investigate the effect of different limb blood-flow levels on cycling-performance recovery, blood lactate concentration, and heart rate.Methods:Thirty-three high-intensity intermittent-trained athletes completed two 30-s Wingate anaerobic test sessions, 3 × 30-s (WAnT 1–3) and 1 × 30-s (WAnT 4), on a cycling ergometer. WAnT 1–3 and WAnT 4 were separated by a randomly assigned 24-min recovery intervention selected from among blood-flow restriction, passive rest, placebo stimulation, or neuromuscular electrical-stimulation-induced blood flow. Calf arterial inflow was measured by venous occlusion plethysmography at regular intervals throughout the recovery period. Performance was measured in terms of peak and mean power output during WAnT 1 and WAnT 4.Results:After the recovery interventions, a large (r = .68 [90% CL .42; .83]) and very large (r = .72 (90% CL .49; .86]) positive correlation were observed between the change in calf arterial inflow and the change in mean and peak power output, respectively. Calf arterial inflow was significantly higher during the neuromuscular-electrical-stimulation recovery intervention than with the blood-flow-restriction, passive-rest, and placebo-stimulation interventions (P < .001). This corresponds to the only intervention that allowed performance recovery (P > .05). No recovery effect was linked to heart rate or blood lactate concentration levels.Conclusions:For the first time, these data support the existence of a positive correlation between an increase in blood flow and performance recovery between bouts of high-intensity exercise. As a practical consideration, this effect can be obtained by using neuromuscular electrical stimulation-induced blood flow since this passive, simple strategy could be easily applied during short-term recovery.

The aim of the present work is to study the impact of the availability of carbohydrates on performance and on the development of training adaptations. The first section of this thesis aimed at defining the optimal recovery strategies between training sessions for elite BMX pilots. The results revealed that the nutritional strategy is one of the most efficient recovery strategies leading to a lesser decrease in power output. The second section of this thesis investigated the impact of a chronic periodization of carbohydrate intake, through the “Sleep-Low” strategy, on endurance performance and immune function. The “Sleep-Low” strategy consists in specific training sessions performed under low carbohydrate availability, notably during recovery period and low intensity prolonged sessions. All subjects training under the “Sleep-Low” strategy improved their performance on a 10km running trial and on a 20km cycling time trial. This improved performance is associated with a modification of pacing strategy during the 20km cycling time trial toward higher power output. The results suggested a modification of perception of effort after training under the “Sleep-Low” strategy: despite an improvement of performance, participants did not perceive the effort as more difficult. These results are associated to a decrease in fat mass. The study #3 confirmed that the periodization of carbohydrate intake did not impair immune function or sleep efficacy. All the results of the four studies bring new elements in the evolution of carbohydrate recommendations. These works are in the line of a manipulation of carbohydrate availability according to the work required; Ces travaux ont visé à étudier l’impact de la disponibilité glucidique sur la performance et les adaptations de l’entraînement. L’étude n°1 a permis de caractériser la stratégie de récupération optimale entre deux entraînements chez des athlètes élites en BMX. Les résultats ont permis d’identifier la stratégie nutritionnelle comme étant la stratégie de récupération induisant la plus faible diminution de puissance lors de tests de performance. La deuxième partie a investigué l’impact de la périodisation chronique de l’apport glucidique, par la stratégie « Sleep-Low », sur la performance en endurance et la fonction immunitaire. La stratégie « Sleep-Low» consiste à réaliser des entraînements ciblés en condition de faible disponibilité en glucides, notamment une période récupération faible en glucides et un entraînement à faible intensité réalisé à jeun. Les résultats révèlent que tous les sujets de la stratégie « Sleep-Low » améliorent leur performance en endurance lors d’un 10km en course à pied ou d’un contre-la-montre de 20km. Cette amélioration de la performance est associée à une modification de la stratégie d’allure dans le cas d’un contre-la-montre vers une augmentation des niveaux de puissance développés. Les résultats ont suggéré une modification de la perception d’effort suite à l’implémentation de la stratégie. Ces résultats sont associés à une diminution de la masse grasse chez les participants. L’étude n°3 confirme que la stratégie « Sleep-Low » n’entraîne pas de dégradation de la fonction immunitaire ou de l’efficacité de sommeil. Ces travaux vont dans le sens d’une manipulation de la disponibilité en glucides en fonction de l’objectif des périodes d’entraînement

Daily tasks of firefighters may induce significant musculoskeletal constraints, cardiovascular risks, burnout and injuries. The aim of this doctoral work was to characterize the specific injuries of French firefighters, and to analyze influence of physical activity (PA), burnout, coping strategies, personality traits, and achievement goal in this injury occurrence. We hypothesize that injuries of French firefighters would be explained by both psychological and physiological factors. Through four experimental studies, the main results indicate that ankle sprain is the major injury in this population. Although SP missions are dangerous and varied, paradoxically injuries occur during the hours of PA practice in day guard. In addition, the total number of hours AP practiced per week is associated with injury. We also observed that the performances achieved in the Y-balance test, the "weight bearing lunge test" are predictive of ankle sprains. Although our investigations have highlighted that the injury was caused by psychological (e.g., burnout) and physiological factors, practicing sessions of AP is compulsory and required in this job, and paradoxically remains the largest provider of occupational incident; Les tâches quotidiennes exercées par les sapeurs-pompiers (SP) peuvent induire d’importantes contraintes musculo-squelettiques, des risques cardiovasculaires, du burnout et des blessures. L’objectif de ce travail doctoral est de caractériser la blessure des SP français et d’analyser l’influence de la pratique d’activité physique AP), du burnout, des stratégies de coping, des traits de personnalité, et des buts d’accomplissement dans l’occurrence des blessures. Nous défendons la thèse selon laquelle la blessure des SP français serait expliquée à la fois par des facteurs psychologiques et physiologiques. Au travers de quatre études expérimentales, les principaux résultats obtenus indiquent que l’entorse de la cheville est la blessure majeure dans cette population. Même si les missions des SP sont dangereuses et variées, les blessures surviennent paradoxalement au cours des heures de pratique de l’AP pendant les jours de garde. De plus, le nombre d’heures d’AP total pratiqué par semaine est associé aux blessures. Nous observons également que les performances réalisées au Y-balance test, au « weight bearing lunge test » sont prédictives de l’entorse de la cheville. Même si nos investigations permettent de mettre en évidence que la blessure est à la fois causée par des facteurs psychologiques (e.g., burnout) et physiologiques, la pratique de l’AP, obligatoire et nécessaire chez les SP, demeure paradoxalement le plus grand pourvoyeur d’accident de travail

The purpose of this work is to examine whether performance supercompensation during taper is maximized in endurance athletes after experiencing overreaching during an overload training period. This first study showed that 1) greater gains in performance and V˙O2max can be achieved when higher training load is prescribed before the taper but not in the presence of functional overreaching (F-OR); 2) peak performance is not delayed during taper when heavy training loads are completed immediately prior; and 3) F-OR provides higher risk for training maladaptation, including increased infection risks. The second study confirms sleep disturbances and increased illness in endurance athletes who present with symptoms of F-OR during periods of high volume training. The third study shows a lower cardiac output and systolic blood pressure with greater arteriovenous O2 difference were reported in F-OR subjects at all exercising intensities, while no significant change was observed in the control and acute fatigue (AF) groups. A concomitant decrease in epinephrine excretion was reported only in the F-OR group. All values returned to baseline at Post. Following an overload endurance training program leading to F-OR, the cardiac response to exhaustive exercise is transiently impaired, possibly due to reduced epinephrine excretion. This finding is likely to explain the complex process of underperformance syndrome experienced by F-OR endurance athletes during heavy load programs; L’entraînement dans les sports d’endurance à haut niveau passe traditionnellement par des périodes de très fortes charges visant à imposer de forts stress. La littérature suggère que ces périodes seront d’autant plus intéressantes si elles sont associées à un important niveau de fatigue et à une diminution de performance (surmenage fonctionnel, SF). Cependant, il n’a jamais été comparé à une surcharge d’entraînement sans diminution de performance (fatigue aigüe, FA). La première partie a montré que la surcompensation de performance au cours de l’affûtage peut répondre de façon Gaussienne à la charge d’entraînement imposée avant l’affûtage. Plus précisément, les résultats ont démontré que l’augmentation de la charge d’entraînement avant l’affûtage peut maximiser la réponse positive à l’entraînement, seulement à condition que le stress d’entraînement ne dépasse pas la capacité de récupération de l’athlète et ne précipite pas de SF. Par ailleurs, il s’avère que les réponses d’affûtage semblent individuelles et non influencées par le niveau de fatigue généré en amont. Ces différences de performance s’expliquent notamment par une bonne adaptation à l’entraînement après une période de surcharge sans SF, quand un état de SF sera à l’inverse associé à une moins bonne adaptation et à une plus grande survenue d’états de santé infectieux. La seconde partie a suggéré que la fatigue observée au sein du groupe SF pouvait également avoir été causée par un phénomène de fatigue cardiaque. En effet, le développement du SF chez l’athlète entraîné est associé à une réduction des valeurs de débit cardiaque à l’exercice

International audience; Intrinsic motivation (IM) is often viewed as a spontaneous tendency for action. Recent behavioral and neuroimaging evidence indicate that IM, in comparison to extrinsic motivation (EM), solicits the motor system. Accordingly, we tested whether IM leads to greater excitability of the motor cortex than EM. To test this hypothesis, we used two different tasks to induce the motivational orientation using either words representing each motivational orientation or pictures previously linked to each motivational orientation through associative learning. Single-pulse transcranial magnetic stimulation over the motor cortex was applied when viewing the stimuli. Electromyographic activity was recorded on the contracted first dorsal interosseous muscle. Two indexes of corticospinal excitability (the amplitude of motor-evoked potential and the length of cortical silent period) were obtained through unbiased automatic detection and analyzed using a mixed model that provided both statistical power and a high level of control over all important individual, task, and stimuli characteristics. Across the two tasks and the two indices of corticospinal excitability, the exposure to IM-related stimuli did not lead to a greater corticospinal excitability than EM-related stimuli or than stimuli with no motivational valence (ps>.20). While these results tend to dismiss the advantage of IM at activating the motor cortex, we suggest alternative hypotheses to explain this lack of effect, which deserves further research.

International audience; OBJECTIVE: We assessed the virological efficacy of a 6 month maraviroc/raltegravir simplification strategy following 6 months of quadruple therapy combining tenofovir disoproxil fumarate/emtricitabine with maraviroc/raltegravir. METHODS: HIV-1-infected naive patients were enrolled in an open label, single-arm, Phase 2 trial. All patients received maraviroc 300 mg twice daily, raltegravir 400 mg twice daily and tenofovir/emtricitabine for 24 weeks. Patients with stable HIV-RNA \\textless50 copies/mL stopped tenofovir/emtricitabine at week (W) 24 and pursued maraviroc/raltegravir until W48. The primary endpoint was the virological response defined by HIV-RNA \\textless50 copies/mL at W48. RESULTS: Thirty-three patients were analysed. Patients were mostly male (94%), Caucasians (91%), MSM (82%); their median age was 42 years. At baseline, median CD4 cell count was 453 cells/mm3 and HIV-RNA was 4.3 log copies/mL. All patients had CCR5-tropic viruses by genotropism and phenotropism assays. All but one patient had an HIV-RNA \\textless 50 copies/mL at W24 and entered the simplification phase. Virological success was maintained at W48 in 88% (90% CI 79%-97%) of patients. N155H mutation was detected at failure in one patient. No tropism switch was observed. Raltegravir and maraviroc plasma exposure were satisfactory in 92% and 79% of 41 samples from 21 patients. Five severe adverse events (SAEs) were observed up to W48; none was related to the study drugs. Four patients presented grade 3 AEs; none was related to the study. No grade 4 AE was observed. No patient died. CONCLUSIONS: Maraviroc/raltegravir maintenance therapy following a 6 month induction phase with maraviroc/raltegravir/tenofovir/emtricitabine was well tolerated and maintained virological efficacy in these carefully selected patients

International audience; Virtual Reality (VR) technology enables ``embodied interactions'' in realistic environments where users can freely move and interact, with deep physical and emotional states. However, a comprehensive understanding of the embodied user experience is currently limited by the extent to which one can make relevant observations, and the accuracy at which observations can be interpreted. Paul Dourish proposed a way forward through the characterisation of embodied interactions in three senses: ontology, intersubjectivity, and intentionality. In a joint effort between computer and neuro-scientists, we built a framework to design studies that investigate multimodal embodied experiences in VR, and apply it to study the impact of simulated low-vision on user navigation. Our methodology involves the design of 3D scenarios annotated with an ontology, modelling intersubjective tasks, and correlating multimodal metrics such as gaze and physiology to derive intentions. We show how this framework enables a more fine-grained understanding of embodied interactions in behavioural research.

International audience; This study aimed to compare different ultrasound devices with magnetic resonance spectroscopy (MRS) to quantify muscle lipid content from echo intensity (EI). Four different ultrasound devices were used to measure muscle EI and subcutaneous fat thickness in four lower-limb muscles. Intramuscular fat (IMF), intramyocellular (IMCL) and extramyocellular lipids (EMCL) were measured using MRS. Linear regression was used to compare raw and subcutaneous fat thickness-corrected EI values to IMCL, EMCL and IMF. IMCL had a poor correlation with muscle EI (r = 0.17-0.32, NS), while EMCL (r = 0.41-0.84, p < 0.05-p < 0.001) and IMF (r = 0.49-0.84, p < 0.01-p < 0.001) had moderate to strong correlation with raw EI. All relationships were improved when considering the effect of subcutaneous fat thickness on muscle EI measurements. The slopes of the relationships were similar across devices, but there were some differences in the y-intercepts when raw EI values were used. These differences disappeared when subcutaneous fat thickness-corrected EI values were considered, allowing for the creation of generic prediction equations (r = 0.41-0.68, p < 0.001). These equations can be used to quantify IMF and EMCL within lower limb muscles from corrected-EI values in non-obese subjects, regardless of the ultrasound device used.

International audience; In four experiments, we tested whether embodied triggers may reduce stereotype threat. We predicted that left-side sensorimotor inductions would increase cognitive performance under stereotype threat, because such inductions are linked to avoidance motivation among right-handers. This sensorimotor-mental congruence hypothesis rests on regulatory fit research showing that stereotype threat may be reduced by avoidance-oriented interventions, and motor congruence research showing positive effects when two parameters of a motor action activate the same motivational system (avoidance or approach). Results indicated that under stereotype threat, cognitive performance was higher when participants contracted their left hand (Study 1) or when the stimuli were presented on the left side of the visual field (Studies 2-4), as compared with right-hand contraction or right-side visual stimulation. These results were observed on math (Studies 1, 2, and 4) and Stroop (Study 3) performance. An indirect effect of congruence on math performance through subjective fluency was also observed.

International audience; In the field of health psychology, the control has consistently been considered as a protective factor. This protective role has been also highlighted in eating attitudes' domain. However, current studies use the one-dimensional scale of Rotter or the multidimensional health locus of control scale, and no specific eating attitudes' scale in the sport context exists. Moreover, the social influence in previous scales is limited. According to recent works, the purpose of this study was to test the internal and external validity of a multidimensional locus of control scale of eating attitudes for athletes. One hundred and seventy-nine participants were solicited. A confirmatory factorial analysis was conducted in order to test the internal validity of the scale. The scale external validity was tested in relation to eating attitudes. The internal validity of the scale was verified as well as the external validity, which confirmed the importance of taking into consideration social influences. Indeed, the 2 subscales " Trainers, friends " and " Parents, family " are related respectively positively and negatively in eating disorders.; Les travaux en psychologie de la santé considèrent généralement le fait d'exercer du contrôle comme un facteur protecteur. Ce rôle protecteur a également été montré dans le domaine des comportements alimentaires. Cependant, les précédentes études utilisaient soit l'échelle unidimensionnelle de Rotter, soit l'échelle multidimensionnelle spécifique à la santé. Aucune échelle spécifique aux comportements alimentaires n'existe. De plus, la prise en compte des facteurs sociaux dans les précédentes échelles est limitée. En s'appuyant sur des travaux récents, l'objectif de cette étude était de proposer une échelle de locus de contrôle multidimensionnelle, prenant en compte l'environnement social du sportif et de tester sa validité interne. La validité externe de cette échelle a également été testée en relation avec les comportements alimentaires. Les résultats montrent une bonne validité interne et externe de l'échelle et confirment l'importance de la prise en compte des influences sociales. En effet, les 2 sous-dimensions « Entraîneurs, amis » et « Parents, famille » sont celles associées respectivement positivement et négati-vement aux troubles alimentaires.

International audience; Among the running field tests that measure aerobic fitness indirectly , the 20-m shuttle run test is the one most commonly used among obese youth. However, this back and forth running test induces premature cessation of exercise in this population. The present study aimed to examine the psycho-physiological responses of obese adolescents to an intermittent (15-15) progressive and maximal run test as compared with a continuous shuttle run test. Eleven obese adolescents (age: 14-15 years; BMI = 34.01 ± 5.30 kg • m-2) performed both tests. A two-way ANOVA examined the main effects of the running test, participant's sex, and their interaction on maximal aerobic performance (net exercise duration and final velocity), physiological values (heart rate, pulmonary oxygen uptake, respiratory exchange ratio and blood lactate concentration) and psychological responses (rating of perceived exertion, and physical self-perceptions). Oxygen uptake and heart-rate values at 9 km • h-1 were also compared. Compared with a 20-m shuttle run, the 15-15 test induced lower pulmonary oxygen uptake values at 9 km/h (28.3 ± 2.7 vs. 35.4 ± 2.7 ml • min-1 • kg-1) and finished with higher maximal velocity and net exercise duration (566 ± 156 vs. 346 ± 156 s, p < 0.001), with no inter-test physiological difference. The 15-15 test also resulted in higher ratings of perceived exertion (16.0 ± 1.2 vs. 12.7 ± 1.6, p < 0.001) and improved perceived physical condition compared with the 20-m shuttle run (+1.4 ± 1.4 vs. +0.2 ± 1.0, p < 0.05). Both tests induced a maximal aerobic power of obese adolescents, but the 15-15 test provided a more progressive speed increment and longer exercise duration. The 15-15 test also elicited a significant improvement of perceived physical condition. In conclusion the 15-15 test can be considered a relevant field test for assessing the aerobic fitness of obese adolescents.

International audience

International audience; OBJECTIVE:Our objective was to compare the use of both anteroposterior (AP) extended-knee X-ray and semi-flexed X-ray (current gold standard) versus the use of semi-flexed X-ray alone to detect femoro-tibial osteoarthritis (OA).METHODS:Individuals 40 to 75 years of age with symptomatic hip and/or knee OA (Kellgren/Lawrence [KL] score≥2) were recruited using a multiregional prevalence survey in France. Both AP and schuss X-rays were performed and read; two years later, the same examiner, blinded to the results of the first reading, performed a second reading of the schuss X-ray. We compared the KL stages of each knee and analyzed osteophyte detection and localization, joint space narrowing (JSN), and the relationship to obesity.RESULTS:The analysis included 350 participants with OA of various stages. Comparing the two readings showed that a higher proportion of patients had KL≥2 when the two X-ray views were combined (right knee: P

Epub 2015 Jan 31; The objective of this study was to characterize the mechanics of maximal running sprint acceleration in high-level athletes. Four elite (100-m best time 9.95-10.29 s) and five sub-elite (10.40-10.60 s) sprinters performed seven sprints in overground conditions. A single virtual 40-m sprint was reconstructed and kinetics parameters were calculated for each step using a force platform system and video analyses. Anteroposterior force (FY), power (PY), and the ratio of the horizontal force component to the resultant (total) force (RF, which reflects the orientation of the resultant ground reaction force for each support phase) were computed as a function of velocity (V). FY-V, RF-V, and PY-V relationships were well described by significant linear (mean R(2) of 0.892 ± 0.049 and 0.950 ± 0.023) and quadratic (mean R(2) = 0.732 ± 0.114) models, respectively. The current study allows a better understanding of the mechanics of the sprint acceleration notably by modeling the relationships between the forward velocity and the main mechanical key variables of the sprint. As these findings partly concern world-class sprinters tested in overground conditions, they give new insights into some aspects of the biomechanical limits of human locomotion.

International audience; The influence of vitamin and mineral complex supplementation on muscular activity and cycling efficiency was examined in elderly endurance-trained master athletes during a heavy cycling trial. Master athletes were randomly assigned in a double-blind process to 1 of 2 treatment groups: antioxidant supplementation (n = 8: As group) or placebo (n = 8: Pl group) for 21 days. After that time, each subject had to perform a 10-min session of cycling on a cycloergometer at a heavy constant intensity. Twenty-four to 48 h after this session, subjects performed an isometric maximal voluntary contraction before and immediately after a fatiguing strength training (leg press exercise) and the same 10-min cycling test after fatigue. Isometric maximal voluntary force (MVF) of knee extensors was assessed before and after fatigue. Electromyographic (EMG) activity of the vastus medialis, the vastus lateralis (VL), and the biceps femoris was recorded with surface EMG. The knee-extensors MVF after the fatiguing exercise was reduced in similar proportions for both groups (As, –10.9%; Pl, –11.3%, p < 0.05). This MVF loss was associated with a significant reduction in EMG frequency parameters for both groups, with a lower decrease for the As group. Muscular activity and cycling efficiency during the cycling bouts were affected by the treatment. Cycling efficiency decreased significantly and the oxygen uptake slow component was higher after the fatiguing exercise for both groups. Furthermore, a decrease in cycling efficiency was associated with an increase in VL activity. However, these changes were significantly lower for the As group. The results of the present study indicate an overall positive effect of vitamin and mineral complex supplementation on cycling efficiency after fatigue, in the endurance-trained elderly.; L'objet de cette étude était d'analyser l'influence d'une supplémentation en vitamines et minéraux sur la performance musculaire et le rendement au cours d'un exercice de cyclisme intense. Deux groupes de 8 personnes âgées régulièrement entrainées en endurance, ont été constitués selon une procédure en double aveugle avec l'apport soit d'un complexe d'antioxydants (n = 8 : groupe As), soit d'un placebo (n = 8 : groupe Pl) pendant 21 jours. Après 21 jours de supplémentation chaque sujet devait effectuer une session de cyclisme de 10 min à une intensité intense. 24 à 48 h après cette session les sujets réalisait un test d'évaluation de la force maximale volontaire (FMV) avant et après une séance d'entrainement en résistance et le même exercice de cyclisme après fatigue. La force maximale isométrique volontaire (FMV) des extenseurs du genou était testée avant et après fatigue. L'activité électromyographique (EMG) du vastus medialis (VM), vastus lateralis (VL) et biceps femoris (BF) était enregistrée à partir d'électrodes de surface. La FMV des muscles extenseurs du genou était réduite après l'exercice fatigant, dans des proportions similaires pour les 2 groupes (As, –10,9%; Pl, –11,3%, p < 0,05). Cette baisse de la FMV était accompagnée d'une réduction des paramètres EMG fréquentiels, pour les 2 groupes, avec toutefois une moindre diminution pour le groupe As. La tolérance à l'exercice en cyclisme était modifiée entre les 2 sessions. Le rendement en cyclisme était réduit et la composante lente de consommation d'oxygène était augmentée pour les 2 groupes après l'exercice fatigant. Cette altération du rendement en cyclisme était accompagnée d'une augmentation de l'activité musculaire du VL. Néanmoins ces changements étaient significativement moindres pour le groupe As. Les résultats de cette étude suggèrent un effet bénéfique d'une supplémentation en vitamines et minéraux sur le rendement en cyclisme après fatigue, chez des personnes âgées entraînées en endurance. Mots-clés : vieillissement, électromyographie, rendement en cyclisme, force maximale volontaire, athlète master.

International audience; PurposeManagers' actions can facilitate the return to work (RTW) process for breast cancer survivors (BCS). However, data on BCS' experiences of managers' actions regarding RTW are dispersed across multiple qualitative studies and do not offer useful insights for managers to support employees returning to work. This study aimed to summarize and map managers' actions experienced by BCS over three RTW phases (before, during, after) and categorize them as facilitating or hindering RTW.MethodsA scoping review of qualitative studies was conducted. Four databases (MEDLINE, PsycINFO, Cochrane Library, EMBASE) were systematically searched for articles published between 2000 and 2022. Studies and participant characteristics were extracted using an excel spreadsheet. A thematic analysis with a predominantly deductive and semantic approach was conducted.ResultsTwenty-nine studies were included after screening 1042 records. Five themes were generated from the data. Two themes addressed the phase 'before RTW': 'managers' interpersonal skills' and 'preparing for RTW'; three in the 'during RTW' phase: 'managers' interpersonal skills', 'offering work flexibility', and 'offering work accommodations', and only one, 'paying attention to follow-up', was addressed in the 'after RTW' phase.ConclusionThis review mapped managers' actions experienced by BCS in three phases of the RTW process. Results suggested that, according to BCS, managers need to mobilize specific skills to provide appropriate support during the RTW process. Further research is needed to better understand the skills underlying managers' actions facilitating the RTW process.

International audience; Objective: The main goal of the athletes who undergo anterior cruciate ligament reconstruction (ACLR) surgery is a successful return-to-sport. At this stage, identifying muscular deficits becomes important. Hence, in this study, three discriminative features based on surface electromyographic signals (sEMG) acquired in a dynamic protocol are introduced to assess the damping ability and interpret activation patterns in lower-limb muscles of ACLR athletes. Methods: The features include the median frequency of the power spectrum density (PSD), the relative percentage of the equivalent damping or equivalent stiffness derived from the median frequency, and the energy of the signals in the time-frequency plane of the pseudo-Wigner-Ville distribution (PWVD). To evaluate the features, 11 healthy and 11 ACLR athletes (6 months post-reconstruction surgery) were recruited to acquire the sEMG signals from the medial and the lateral parts of the hamstrings, quadriceps, and gastrocnemius muscles in pre- and post-fatigue single-leg landings. Results: A significant damping deficiency is observed in the hamstring muscles of ACLR athletes by evaluating the proposed features. This deficiency indicates that more attention should be paid to this muscle of ACLR athletes in pre-return-to-sport rehabilitations. Conclusion: The quality of electromyography-based pre-return-to-sport assessments on ACLR subjects depends on the sEMG acquisition protocol, as well as the type and nature of the extracted features. Hence, combinatorial application of both energy-based features (derived from the PWVD) and power-based features (derived from the PSD) could facilitate the assessment process by providing additional biomechanical information regarding the behavior of the muscles surrounding the knee.

Epub 2015 Jul 17; Overground sprint studies have shown the importance of net horizontal ground reaction force impulse (IMPH) for acceleration performance, but only investigated one or two steps over the acceleration phase, and not in elite sprinters. The main aim of this study was to distinguish between propulsive (IMPH+) and braking (IMPH−) components of the IMPH and seek whether, for an expected higher IMPH, faster elite sprinters produce greater IMPH+, smaller IMPH−, or both.Nine high-level sprinters (100-m best times range: 9.95–10.60 s) performed 7 sprints (2×10 m, 2×15 m, 20 m, 30 m and 40 m) during which ground reaction force was measured by a 6.60 m force platform system. By placing the starting-blocks further from the force plates at each trial, and pooling the data, we could assess the mechanics of an entire “virtual” 40-m acceleration.IMPH and IMPH+ were significantly correlated with 40-m mean speed (r=0.868 and 0.802, respectively; P

International audience; Background/Study Context: Based on the stereotype content model and the behaviors from intergroup affect and stereotypes map (Cuddy et al., 2008; Advances in experimental social psychology [Vol. 40, pp. 61–149], New York: Academic Press), we examined whether being physically active may challenge the traditional stereotypes related to older adults.Methods: We compared how 94 participants (Mage = 24.48 years, SD = 7.15 years) judged one of three target groups (older adults in general, physically active older adults, and socially active older adults), with regard to perceived status and competition, warmth and competence judgments, emotional and behavioral reactions.Results: Results showed that being physically active was associated with higher status and competence. Physically active older adults were specifically viewed as an admired group eliciting both active (helping) and passive facilitation (associating) tendencies.Conclusion: Beyond the well-known health perspective related to the regular participation of older adults in physical activity, the present results open a social optimistic perspective, in which being physically active seems a promising way to challenge the widespread and resistant stereotype content of older people commonly perpetuated.

International audience; This study aimed to validate a simple field method for determining force– and power–velocity relationships and mechanical effectiveness of force application during sprint running. The proposed method, based on an inverse dynamic approach applied to the body center of mass, estimates the step-averaged ground reaction forces in runner's sagittal plane of motion during overground sprint acceleration from only anthropometric and spatio-temporal data. Force– and power–velocity relationships, the associated variables, and mechanical effectiveness were determined (a) on nine sprinters using both the proposed method and force plate measurements and (b) on six other sprinters using the proposed method during several consecutive trials to assess the inter-trial reliability. The low bias (

International audience; Purpose: This study aimed to investigate whether workload intensity modulates exercise-induced effect on reaction time (RT) performances, and more specifically to clarify whether cognitive control that plays a crucial role in rapid decision making is altered. Methods: Fourteen participants performed a Simon Task while cycling 20 min at a light (first ventilatory threshold, VT1 - 20%), moderate (VT1), or very hard (VT1 + 20%) level of exercise. Results: After 15 min of cycling, RTs are faster than during the first 5 min of exercise. This benefit does not fluctuate with the intensity of exercise and enlarges as RT lengthens. Despite a numerical difference suggesting a greater facilitation during moderate exercise (-16 ms) than during a light exercise (-10 ms), the benefit is not statistically different. Interestingly, we did not observe any signs of worsening on RT or on accuracy during very hard exercise. Conclusion: Cognitive control is extremely robust and appears not to be affected by the intensity of exercise. The selective inhibition and the between-trials adjustments are effective from the beginning to the end of exercise, regardless of the workload output. Copyright (C) 2015, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.

International audience; This study aimed at investigating concurrent changes in cognitive control and cerebral oxygenation (Cox) during steady intense exercise to volitional exhaustion. Fifteen participants were monitored using prefrontal near-infrared spectroscopy and electromyography of the thumb muscles during the completion of an Eriksen flanker task completed either at rest (control condition) or while cycling at a strenuous intensity until exhaustion (exercise condition). Two time windows were matched between the conditions to distinguish a potential exercise-induced evolutive cognitive effect: an initial period and a terminal period. In the initial period, Cox remained unaltered and, contrary to theoretical predictions, exercise did not induce any deficit in selective response inhibition. Rather, the drop-off of the delta curve as reaction time lengthened suggested enhanced efficiency of cognitive processes in the first part of the exercise bout. Shortly before exhaustion, Cox values were severely reduced - though not characteristic of a hypofrontality state - while no sign of deficit in selective response inhibition was observed. Despite this, individual's susceptibility to making fast impulsive errors increased and less efficient online correction of incorrect activation was observed near exhaustion. A negative correlation between Cox values and error rate was observed and is discussed in terms of cerebral resources redistribution. (C) 2015 Elsevier Ltd. All rights reserved.

International audience; There is now a large body of evidence showing that many different conditions related to impaired fronto-executive functioning are associated with the enhancement of some types of creativity. In this paper, we pursue the possibility that the central mechanism associated with this effect might be a reduced capacity to exert inhibition. We tested this hypothesis by exhausting the inhibition efficiency through prolonged and intensive practice of either the Simon or the Eriksen Flanker task. Performance on another inhibition task indicated that only the cognitive resources for inhibition of participants facing high inhibition demands were impaired. Subsequent creativity tests revealed that exposure to high inhibition demands led to enhanced fluency in a divergent thinking task (Alternate Uses Task), but no such changes occurred in a convergent task (Remote Associate Task; studies la and lb). The same manipulation also led to a hyper-priming effect for weakly related primes in a Lexical Decision Task (Study 2). Together, these findings suggest that inhibition selectively affects some types of creative processes and that, when resources for inhibition are lacking, the frequency and the originality of ideas was facilitated. (C) 2014 Elsevier B.V. All rights reserved.

The purpose of this study was to determine whether the excessive spikes observed in the surface electromyography (sEMG) spectrum recorded during whole-body vibration (WBV) exercises contain motion artifacts and/or reflex activity. The occurrence of motion artifacts was tested by electrical recordings of the patella. The involvement of reflex activity was investigated by analyzing the magnitude of the isolated spikes during changes in voluntary background muscle activity. Eighteen physically active volunteers performed static squats while the sEMG was measured of five lower limb muscles during vertical WBV using no load and an additional load of 33 kg. In order to record motion artifacts during WBV, a pair of electrodes was positioned on the patella with several layers of tape between skin and electrodes. Spectral analysis of the patella signal revealed recordings of motion artifacts as high peaks at the vibration frequency (fundamental) and marginal peaks at the multiple harmonics were observed. For the sEMG recordings, the root mean square of the spikes increased with increasing additional loads (p0.05), and was significantly correlated to the sEMG signal without the spikes of the respective muscle (r range: 0.54 - 0.92, p0.05). This finding indicates that reflex activity might be contained in the isolated spikes, as identical behavior has been found for stretch reflex responses evoked during direct vibration. In conclusion, the spikes visible in the sEMG spectrum during WBV exercises contain motion artifacts and possibly reflex activity. Key pointsThe spikes observed in the sEMG spectrum during WBV exercises contain motion artifacts and possibly reflex activityThe motion artifacts are more pronounced in the first spike than the following spikes in the sEMG spectrumReflex activity during WBV exercises is enhanced with an additional load of approximately 50% of the body mass.

Older adults are not sufficiently active against the current recommendations. The approach adapted in this thesis was that physical inactivity was partly due to psychological barriers, notably aging stereotypes. The main objective of this thesis was to identify the role of aging stereotypes, and their relation with physical activity. We defend the thesis that aging stereotypes affect older adults’ health-behaviors. In the first study, we contribute to the validation of a psychometric tool which measuring aging stereotypes in the physical activity domain. The second study reveals that openness to experience and implicit theories of ability are personal correlates of internalization of aging stereotypes, and are linked to the level of physical activity in older adults. The third study shows that endorsement of aging stereotypes in physical activity domain predicted health though ego depletion, including lowering the subjective vitality in active older adults. The fourth study suggests that incremental theories of ability are more effective on a task related to the physical capacities when counter-stereotypical information is given. The last study of this thesis shows that older adults who participated on exercise program combined with psychosocial intervention report higher scores of stereotypes related to benefits of the physical activity, physical self-perceptions, quality of life and physical endurance, and lower scores of stereotypes relative to risks of physical activity.; Les seniors ne sont pas suffisamment active au regard des recommandations actuelles. Cette inactivité physique serait due en partie à des barrières psychologiques ; les stéréotypes liés au vieillissement. L’objectif de cette thèse est d’identifier le rôle de ces stéréotypes, et leurs conséquences sur l’activité physique. La première étude est la continuité de l’élaboration et de la validation d’un outil psychométrique mesurant les stéréotypes liés à la pratique de l’activité physique des seniors. La deuxième étude révèle que l’ouverture aux expériences et les théories implicites de l’habileté sont des corrélats personnels de l’internalisation des stéréotypes liés au vieillissement, et sont reliés au niveau d’activité physique des seniors. La troisième étude montre que l’adhésion aux stéréotypes liés au vieillissement dans le domaine de l’activité physique prédit la santé par l’ego déplétion en diminuant la vitalité de seniors actifs. La quatrième étude suggère que les théories incrémentielles sont plus efficaces sur une tâche de force lorsqu’elles sont associées à des informations contre-stéréotypées. La dernière étude révèle que les seniors bénéficiant d’un programme de marche et d’une intervention psychosociale, ont obtenu des scores plus élevés de stéréotypes bénéfices de l’activité physique, de perceptions de la valeur physique et de la compétence sportive, d’apparence physique, de qualité de vie et d'endurance physique, et des scores plus faibles de stéréotypes risques de l’activité physique. Ces résultats indiquent que ces stéréotypes ont évolué positivement chez des femmes seniors sédentaires, apportant ainsi un appui à une conception malléable des stéréotypes.

The aim of this thesis was to analyze the effect of whole-body vibration (WBV) exercise on lower limb muscle activity and to give methodological implications and practical applications. Two methodological studies were conducted that served to evaluate the optimal method to process the surface electromyography (sEMG) signals during WBV exercise and to analyze the influence of the normalization method on the sEMG activity. A third study aimed to gain insight whether the isolated spikes in the sEMG spectrum contain motion artifacts and/or reflex activity. The subsequent three investigations aimed to explore how the muscle activity is affected by WBV exercise, with a particular focus on the vibration frequency, platform amplitude, additional loading, platform type, knee flexion angle, and the fitness status of the WBV user. The final goal was to evaluate the minimal required vertical acceleration to stimulate the muscle activity of the lower limbs. In summary, the research conducted for this thesis provides implication for future investigations on how to delete the excessive spikes in the sEMG spectrum and how to normalize the sEMG during WBV. The outcomes of this thesis add to the current literature in providing practical applications for exercising on a WBV platform.; L’objectif de cette thèse a été d’analyser l’effet de l’exercice physique réalisé sur plateforme vibrante (whole-body vibration, WBV) sur l’activité musculaire des membres inférieurs, de développer des outils d’analyse méthodologiques et de proposer des recommandations pratiques d’utilisation. Deux études méthodologiques ont été menées pour identifier la méthode optimale permettant de traiter les signaux d'électromyographie de surface (sEMG) recueillis pendant la vibration et d'analyser l'influence de la méthode de normalisation de l'activité sEMG. Une troisième étude visait à mieux comprendre si les pics sEMG observés dans le spectre de puissance du signal contiennent des artéfacts de mouvement et/ou de l'activité musculaire réflexe. Les trois études suivantes avaient pour but de quantifier l’effet de la WBV sur l’activité musculaire en fonction de différents paramètres tels que, la fréquence de vibration, l'amplitude de la plateforme, une charge supplémentaire, le type de plateforme, l'angle articulaire du genou, et la condition physique du sujet. En outre, l'objectif a été de déterminer l'accélération verticale minimale permettant de stimuler au mieux l'activité musculaire des membres inférieurs. En résumé, les recherches menées au cours de cette thèse fournissent des solutions pour de futures études sur : i) comment supprimer les pics dans le spectre du signal sEMG et, ii) comment normaliser l'activité musculaire pendant un exercice WBV. Enfin, les résultats de cette thèse apportent à la littérature scientifique de nouvelles recommandations pratiques liées à l’utilisation des plateformes vibrantes à des fins d’exercice physique.

Spatial navigation is an intricate ability, requiring multisensory and motor integration, that is particularly impacted in aging. The age-related decline in navigational capabilities is known to be associated with changes in brain regions such as the frontal, temporal, and cerebellar cortices. Age-related cerebellar differences in spatial navigation have generally been ascribed to motor impairments, omitting the central role of this structure in several cognitive processes. In the present voxel-based morphometric study, we investigated gray matter volume loss in older adults across cognitive and motor subregions of the cerebellum. Specifically, we hypothesized that age-related gray matter differences would occur mainly in cerebellar regions involved in cognitive processing. Our results showed a significant age-related atrophy in the left neocerebellum of healthy older adults that includes Crus I and lobule VI. The latter are important nodes in the network that subtends cognitive abilities such as object recognition and spatial cognition. This exploratory work sets the ground for future research to investigate the extent of the neocerebellum’s contribution to spatial navigation deficits in aging.

Background The net metabolic cost of walking (NCw) and the co-activation of leg muscles are both higher in old adults (OG) than in young adults (YG). Nevertheless, the relation between the two remains unresolved, mainly due to the controversial co-activation measurement method used in previous studies. Research question To compare ankle and knee co-contraction (CCI), calculated using an EMG-driven method, between the groups and to examine their relationship with NCw. Methods Nine young (YG = 25.2 +/- 3.3 years old) and nine older (OG = 68.7 +/5.9 years old) adults walked on a treadmill at five speeds (YG: 1; 1.2; 1.4; 1.6; 1.8 m/s; OG: 0.6; 0.8; 1; 1.2; 1.4 m/s) while electromyography (sEMG) and oxygen consumption were measured. CCI were calculated around the ankle and knee for different parts of the gait cycle (entire gait cycle 0–100 %, stance phase 0–60 %, swing phase 60–100 %). Results NCw was significantly higher (25 %, averaged over the walking speeds) in OG as were Knee_CCI, Knee_CCI_swing and Knee_CCI_stance. Multiple regression models in YG, OG and YG + OG highlighted Ankle_CCI as the main contributor in NCw (β = 0.08−0.188, p Significance The present findings provide a better understanding of the association between muscle co-contraction and metabolic cost in older adults. It may help scientists and clinicians to further develop strategies aimed at neuromuscular rehabilitation as a means of improving mobility and independence among older adults.

Background Physical activity (PA) is a proven therapeutic tool to increase the quality of life and life expectancy in people with cystic fibrosis (pwCF). Despite this, the PA level of pwCF is lower than recommended. Objectives This study was conducted to identify the barriers to and facilitators of PA in adults with CF with heterogeneous severity. Methods Twenty adults with CF (mean age = 33.3±11.7 years, mean FEV1% = 50.55±20.4%) were recruited from two specialized centers and interviewed about the factors that limit and facilitate their PA. The collected data were transcribed, coded and analyzed using deductive and inductive methods. Results Barriers and facilitators were classified into physical, psychological and environmental dimensions. The main barriers were fatigue, breathing difficulties, lack of available facilities, negative perceptions of PA and perceived health risks. The most important facilitators were respiratory benefits, well-being, and social support. Conclusion Although some barriers and facilitators were similar to those found in children with CF or adults from other vulnerable populations, others were specific to adults with CF, such as the risk of cross-contamination and transplant preparation. The comprehensive study of the barriers and facilitators in adults will enhance PA counseling for pwCF and help improve their compliance with PA recommendations.

The transition from childhood to adulthood is characterized by many physiological processes impacting exercise performance. Performance fatigability and time to task failure are commonly used to capture exercise performance. This review aimed to determine the differences in fatigability and TTF between youth (including both children and adolescents) and young adults, and to evaluate the influence of exercise modalities (i.e., exercise duration and type of exercise) on these differences. Medline, SPORTDiscus and Cochrane Library were searched. Thirty-four studies were included. The meta-analyses revealed that both children (SMD −1.15; p < 0.001) and adolescents (SMD −1.26; p = 0.022) were less fatigable than adults. Additional analysis revealed that children were less fatigable during dynamic exercises (SMD −1.58; p < 0.001) with no differences during isometric ones (SMD –0.46; p = 0.22). Children (SMD 0.89; p = 0.018) but not adolescents (SMD 0.75; p = 0.090) had longer TTF than adults. Additional analyses revealed 1) that children had longer TTF for isometric (SMD 1.25; p < 0.001) but not dynamic exercises (SMD −0.27; p = 0.83), and 2) that TTF differences between children and adults were larger for short- (SMD 1.46; p = 0.028) than long-duration exercises (SMD 0.20; p = 0.64). Children have higher endurance and are less fatigable than adults. These differences are influenced by the exercise modality, suggesting distinct physiological functioning during exercise between children and adults. The low number of studies comparing these outcomes between adolescents versus children and adults prevents robust conclusions and warrants further investigations in adolescent individuals.

International audience; The objective of this study was to develop and validate a French-language questionnaire measuring stereotypes related to exercise in cancer patients: The Cancer Exercise Stereotypes Scale (CESS). Four successive steps were carried out with 806 participants. First, a preliminary version was developed on the basis of the relevant literature and qualitative interviews. A test of clarity then led to the reformulation of six of the 30 items. Second, based on the modification indices of the first confirmatory factorial analysis, 11 of the 30 initial items were deleted. A new factorial structure analysis showed a good fit and validated a 19-item instrument with five subscales. Third, the stability of the instrument was tested over time. Last, tests of construct validity were conducted to examine convergent validity and discriminant validity. The French-language CESS appears to have good psychometric qualities and can be used to test theoretical tenets and inform intervention strategies on ways to foster exercise in cancer patients.

International audience; : We hypothesized that exercise performance is adjusted during repeated sprints in order to not surpass a critical threshold of peripheral fatigue. Twelve men randomly performed three experimental sessions on different days: one single 10 s all-out sprint and two trials of 10 × 10 s all-out sprint with 30 s of passive recovery in between. One trial was performed in the unfatigued state (CTRL) and one following electrically-induced quadriceps muscle fatigue (FTNMES). Peripheral fatigue was quantified by comparing pre- to post-exercise changes in potentiated quadriceps twitch force (Δ Qtw-pot) evoked by supramaximal magnetic stimulation of the femoral nerve. Central fatigue was estimated by comparing pre- to post-exercise voluntary activation of quadriceps motor units. The RMS of the vastus lateralis and vastus medialis EMG normalized by maximal M-wave amplitude (RMS.Mmax(-1)) was also calculated during sprints. Compared to CTRL, pre-existing quadriceps muscle fatigue in FTNMES (Δ Qtw-pot = - 29 ± 4%) resulted in a significant (P < 0.05) reduction in power output (- 4.0 ± 0.9%) associated with a reduction in RMS.Mmax-1. However, Δ Qtw-pot post-sprints decreased by 51% in both conditions indicating that the level of peripheral fatigue was identical, and independent of the degree of pre-existing fatigue. Our findings showed that power output and cycling EMG are adjusted during exercise for the purpose of limiting the development of peripheral fatigue beyond a constant threshold. We hypothesized that the contribution of peripheral fatigue to exercise limitation involves a reduction in central motor drive in addition to the impairment in muscular function.

International audience; BACKGROUND: Transcranial magnetic stimulation (TMS) is a widely-used investigative technique in motor cortical evaluation. Recently, there has been a surge in TMS studies evaluating lower-limb fatigue. TMS intensity of 120-130% resting motor threshold (RMT) and 120% active motor threshold (AMT) and TMS intensity determined using stimulus-response curves during muscular contraction have been used in these studies. With the expansion of fatigue research in locomotion, the quadriceps femoris is increasingly of interest. It is important to select a stimulus intensity appropriate to evaluate the variables, including voluntary activation, being measured in this functionally important muscle group. This study assessed whether selected quadriceps TMS stimulus intensity determined by frequently employed methods is similar between methods and muscles. METHODS: Stimulus intensity in vastus lateralis, rectus femoris and vastus medialis muscles was determined by RMT, AMT (i.e. during brief voluntary contractions at 10% maximal voluntary force, MVC) and maximal motor-evoked potential (MEP) amplitude from stimulus-response curves during brief voluntary contractions at 10, 20 and 50% MVC at different stimulus intensities. RESULTS: Stimulus intensity determined from a 10% MVC stimulus-response curve and at 120 and 130% RMT was higher than stimulus intensity at 120% AMT (lowest) and from a 50% MVC stimulus-response curve (p < 0.05). Stimulus intensity from a 20% MVC stimulus-response curve was similar to 120% RMT and 50% MVC stimulus-response curve. Mean stimulus intensity for stimulus-response curves at 10, 20 and 50% MVC corresponded to approximately 135, 115 and 100% RMT and 180, 155 and 130% AMT, respectively. Selected stimulus intensity was similar between muscles for all methods (p > 0.05). CONCLUSIONS: Similar optimal stimulus intensity and maximal MEP amplitudes at 20 and 50% MVC and the minimal risk of residual fatigue at 20% MVC suggest that a 20% MVC stimulus-response curve is appropriate for determining TMS stimulus intensity in the quadriceps femoris. The higher selected stimulus intensities at 120-130% RMT have the potential to cause increased coactivation and discomfort and the lower stimulus intensity at 120% AMT may underestimate evoked responses. One muscle may also act as a surrogate in determining optimal quadriceps femoris stimulation intensity.

International audience; Objectives :The goal of this study was to identify the personal correlates (openness to experience and implicit theories of ability) of internalization of aging stereotypes and its relationships with physical activity.DesignCross-sectional survey.Method :One hundred and ninety-two older adults (78 men and 114 women) from 60 to 93 years (Mage = 73.44, SD = 7.34) completed a series of questionnaires measuring openness to experience, implicit theories of ability, stereotypes about older people and physical activity, attitude toward own aging, physical self-worth, physical activity level, self-rated health and education level.Results :The main results showed that (a) openness to experience positively predicted physical activity level through incremental theories, endorsement of aging stereotypes relative to benefits, attitude toward own aging, and physical self-worth; and (b) entity theories negatively predicted physical activity level through endorsement of aging stereotypes relative to risks, attitude toward own aging, and physical self-worth.Conclusion :The present study indicates that openness to experience and implicit theories of ability are correlates of endorsement of aging stereotypes and suggests that endorsement may be an important factor of engagement in physical activity in older adults.

International audience; The aim of the present study is to assess the relevance of weight-bearing distribution (DWB) measurement in freely moving rats after stroke and thoracic spinal cord injuries. Animals were divided in 2 experiments: (1) The middle cerebral artery occlusion-reperfusion (MCAO-r) experiment containing the MCAO group in which focal brain ischaemia was induced by transient MCA occlusion and (2) the thoracic hemisection experiment containing the TH group in which a spinal cord hemisection was performed at the T 10 level. A Control and respective Sham groups were also included in each experiment. Not only the pressure exerted by each paw was measured but also different ratios such as: (1) the sum of the right and the left forepaws was normalized by the sum of the right and the left hindpaws (F/H), (2) the left forepaw was normalized by the right forepaw (LF/RF), (3) the left hindpaw was normalized by the right hindpaw (LH/RH). Additionally, the times spent on 3 paws and on 4 paws were measured. Only the time spent on 4 paws was shorter in the MCAO group than in the Control (p < 0.001) and in the Sham (p < 0.01) groups. The LH/RH ratio of the TH group at the 1st week was lower (p < 0.01) than the pre-surgical value. Moreover, its F/H ratio was superior (p < 0.001) to the ones of the Control and the Sham groups. Our study indicates that DWB should be more frequently used to evaluate both the severity of central nervous system traumas and the effectiveness of pharmacological and/or rehabilitation strategies.

International audience; Controlling instructions typically undermine intrinsic motivation. However, in line with an autonomy restoration process, we hypothesized that prior exposure to a controlling context could increase intrinsic motivation displayed in a subsequent task if this second task is devoid of autonomy threats. A correlational study in educational context provided support for this effect by showing that students reported more interest in their music class when it was preceded by a class that was controlling. This effect was replicated in an experiment wherein participants who learned to play a game in a controlling context reported more interest in a second game than those who learned the first game in a neutral context. However, this effect disappears when the two tasks were done in a similar environment. Overall, this suggests that autonomy deprived students would display more intrinsic motivation in a subsequent task if this task gives a glimpse of autonomy satisfaction.