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This study investigated (a) changes in ghrelin and peptide YY (PYY) concentrations during a weight reduction programme and (b) baseline ghrelin and PYY levels as predictors of weight loss in 32 severely obese adolescents (BMI z score = 4.1). Subjects spent an academic year in an institution for childhood obesity. Fasting ghrelin and PYY, leptin, insulin levels and insulin resistance were measured at baseline (month 0) and during the programme (months 3, 6, 9). In addition, 15 normal-weight teenagers served as reference for the baseline assessments. At baseline, obese teenagers had lower ghrelin and PYY concentrations than normal-weight adolescents (P < 0.05). Moreover, they showed significantly higher leptin, insulin levels and homeostasis model assessment (HOMA) (P < 0.0001). During the lifestyle modification, there was a significant decrease in body weight among obese teenagers, associated with an increase in ghrelin (apparent from month 6; P < 0.05), a decrease in leptin (from month 3; P < 0.05) and a decrease in insulin and HOMA (from month 3; P < 0.0001), without any significant change in PYY. Anthropometrical changes were correlated neither with baseline ghrelin levels nor with changes in ghrelin and PYY after the lifestyle modification. However, higher baseline PYY tended to correlate with greater anthropometrical changes (P < 0.1). In adolescents with severe obesity, a long-term combination of supervised aerobic exercises and a balanced diet led to weight reduction and increased ghrelin concentrations, without any change in PYY concentrations. Moreover, baseline PYY concentrations might be considered as predictors of weight loss.

The present study compared the effects of partial sleep deprivation and the effects of an intake of a hypnotic compound (zolpidem) prior to bedtime, on sleep and on hormonal and metabolic adaptations to subsequent exercise. Sleep deprivation consisted of a delayed bedtime and an early getting-up time. Eight young subjects, who slept well and were highly trained athletes, were enrolled in this study. Sleep was recorded polygraphically and the following afternoon exercise was performed on a cycle ergometer for 30 min at 75% of maximal oxygen consumption (VO2max) after a 10-min warm up. Met-enkephalin, β-endorphin, cortisol, and lactate concentrations were measured at rest and during exercise. The data obtained after experimental sleep, with and without medication were compared with those obtained in the reference condition with normal sleep. Both types of sleep reduction decreased the total sleep time, stage 2 sleep, and rapid eye movement sleep, whereas zolpidem administration did not modify either the duration of sleep or the sleep stages. After the reference night, plasma met-enkephalin did not show any significant change at the end of the submaximal exercise, whereas β-endorphin, cortisol, and lactic acid concentrations increased significantly in all subjects. The changes in concentration in β-endorphin were significantly related to the changes in cortisol (r=0.78;P

Phytoestrogens, naturally occurring plant compounds having oestrogenic and/or anti-oestrogenic activity, are present in many human foodstuffs including hop. Moderate intakes of isoflavonoid phytoestrogens have been associated with a reduction in cardiovascular diseases incidence. So, it is possible that hop ( Humulus Lupulus L.) might similarly contribute to the reported health-beneficial effects of moderate beer consumption. Thus, the purpose of this study was to investigate in vitro effects of aqueous hop extract on thoracic vascular reactivity in Sprague Dawley male and female rats. Endothelium-intact thoracic arterial rings from male rats (MALE, n =8), sham-ovariectomized (Sham OVX) female ( n =8) and ovariectomized (OVX) female rats ( n =8) were used. We assessed the relaxation induced by aqueous hop extract (10 −9 , 10 −2 g/l) in aortic rings precontracted with norepinephrine (10 −7 M), in the absence or in the presence of l -NAME (10 −4 M), indomethacin (10 −5 M), thapsigargin (10 −4 M), iberiotoxin (3.10 −8 M), apamin (3.10 −8 M) and TEA (3.10 −4 M). Aqueous hop extract induced relaxation of endothelium-intact thoracic arterial rings in MALE and Sham OVX rats, whereas a weak effect was observed in OVX rats. This vasorelaxation was strongly inhibited in presence of l -NAME, indomethacin and thapsigargin. These data indicated that aqueous hop extract-induced vasodilation, in male and intact female rats, is mediated by NOS activation, cyclooxygenase products and Ca 2+ pathways. Moreover, our results suggested that effect of hop in enhancing vascular reactivity was independent of gender but strongly related to hormonal status.

Resume Les effets d'une privation de trois heures de sommeil en milieu de nuit sur l'adaptation de l'organisme a un exercice physique ont ete etudies chez huit athletes endurants de niveau regional. Les nuits de sommeil precedant l'effort ont ete controlees en laboratoire. L'epreuve d'effort s'est deroulee sur bicyclette ergometrique. Sa chronologie a consiste en quatre etapes: echauffement de 10 minutes, effort sous-maximal a puissance fixe (75% de la consommation maximale d'oxygene) pendant 20 minutes, augmentation progressive de la charge de travail jusqu'a epuisement du sujet et, enfin, recuperation de 15 minutes. A effort sous-maximal stable et a effort maximal supporte, les valeurs de frequence cardiaque, de ventilation, d'equivalent respiratoire pour l'oxygene et de lactatemie sont plus elevees lorsque l'exercice est conduit apres privation partielle de sommeil que celles obtenues lors de l'exercice effectue apres une nuit temoin. A effort maximal, la consommation d'oxygene est abaissee alors que la puissance supportee de travail est identique.

International audience; We investigated in female rats the effects on bone metabolism of a prolonged no-training period, subsequent to an isometric exercise program, performed during young adulthood and those of a long-term consumption of Humulus lupulus L-enriched diet (genistein 1.92 and daidzein 1.24 mg/kg diet) combined or not with isometric training. Forty-eight rats (4 weeks old) were randomly divided into 4 groups: trained (C-Tr) or nontrained rats (C-NTr) fed with control diet and trained (H-Tr) or nontrained rats (H-NTr) fed with Humulus lupulus L-enriched diet. The diets lasted 100 weeks. Training was followed over a 25-week period. Bone parameters were measured at week 100. Our results showed that no significant difference was observed among the 4 groups in uterine relative weight, calcium (Ca) intake, fecal Ca, urinary Ca excretion, net Ca absorption, plasma Ca, and bone Ca content. Calcium balance was significantly enhanced in H-NTr rats in comparison with C-NTr and C-Tr rats. Isometric strength training led to a significant increase in total bone mineral density (BNID), diaphyseal BMD, and osteocalcin-deoxypyridinoline ratio in C-Tr rats compared with the other groups. The main findings of the present study indicate that in female rats, a 25-week isometric strength training performed during young adulthood followed by a prolonged no-training period increases BNID values and osteocalcin-deoxypyridinoline ratio, whereas long-term consumption of Humuluss lupulus L-enriched diet does not improve bone parameters. It suggests that bone gains induced by exercise do not decrease immediately after cessation of training and also confirms the importance of the practice of physical activity during puberty and young adulthood to maximize the achieved peak bone density.

Background Rheumatoid Arthritis (RA) is the most common chronic inflammatory Rheumatism characterized by increased cardiovascular risk. In the general population, WHO proposes specific recommendations on the type of physical activity (PA) to achieve in the context of this cardiovascular risk. In RA patient, the place of PA is not highlighted to take care of the cardiovascular risk. Objectives The aim of this work is to provide the available data about the effects of the PA in RA Methods Systematic review of the literature on PubMed database with the following keywords: “physical activity”, “motor activity”, “Physical exercise” and “Rheumatoid arthritis”. We focused to the studies in humans older than 18 years old and written in English. We identified 401 references, 256 were preselected and 49 were relevant for the analysis. Results RA is responsible for a greater inactivity highlighted with subjective measures (questionnaire) and with objective measures as the total energy expenditure or the accelerometer. Physical activity (PA) reduces significantly cardiovascular risk and DAS28. Physical inactivity and disease activity are correlated (RR 1.65 of inactivity as DAS28>5.1). At the vascular level, it improves endothelial function (improve antioxidant mechanisms and increase eNOS activity) and slows atherosclerosis. At the bone level, it slows radiographic progression of small joints but worsens the radiographic damages of big joints. PA slows bone mineral density loss at the femoral neck (0% of median change of hip bone mineral density versus 1% in the control group after 1 year, p Conclusions The beneficial effects of PA on RA are multiple and its practice should be promoted as part of the patients therapeutic education. Disclosure of Interest None declared

Using female 4-week-old Sprague–Dawley rats, we investigated the effects of 14 weeks of progressive strength isometric training on endothelium dysfunction after estrogen deficiency. We also proposed possible mechanism(s) by which such training acted on endothelium-dependent vasodilation in thoracic aortic rings. Rats were randomly divided into 4 groups of 8 rats: a sham operated group, an ovariectomized sedentary group receiving 17β-estradiol vehicle s.c. daily, an ovariectomized sedentary group receiving a daily injection of 20 µg·kg–1 17β-estradiol s.c., and an ovariectomized exercised group receiving daily s.c. vehicle. Vascular reactivity of aortic rings have been evaluated by a cumulative dose of acetylcholine (ACh), in the presence or absence of l-NAME (N-nitro-l-arginine methyl ester), indomethacin, thapsigargin, iberiotoxin, apamin, and tetraethylammonium. Ovariectomy markedly decreased the relaxation caused by ACh, whereas 17β-estradiol treatment induced a significant increase in the relaxation elicited by ACh. Isometric exercise enhanced relaxation due to ACh. This enhancement was attenuated in the presence of l-NAME, indomethacin, thapsigargin, iberiotoxin, and apamin. Our data indicated, for the first time, that the endothelium-dependent relaxant response to ACh was markedly improved in trained ovariectomized rats. This increased vasodilation is mediated by nitric oxide, cyclooxygenase, sarco-endoplasmic reticulum Ca2+-ATPase pathways, and endothelium-derived hyperpolarizing factor. Finally, this study suggested that resistance training may provide benefits in addressing vascular dysfunction consequent to a decline in estrogen levels after menopause. However, any benefits for age-related vascular dysfunction remain to be demonstrated.

The purpose of the present study was to examine both the specific and the transfer effects of a Square Wave Endurance Exercise Test (SWEET) and to investigate the determining factors of transfer effect. A control group (CG, n = 5) and 2 experimental groups were studied. Experimental groups completed 3 days/week a 45 min SWEET over 6 weeks, either with the arms using a wheelchair ergometer (AG, n = 5) or with the legs using a cycling ergometer (LG, n = 5). All subjects performed before and after training two maximal progressive tests: the first one with the arms and the second with the legs. During those tests oxygen uptake (VO(2)) and cardiorespiratory parameters were continuously measured. Specific effects (changes between the tests performed with trained limbs) were observed: the peak power output (W(p)) and VO(2) were significantly increased by both arm (+ 66 %, + 35 %) and leg (+ 17 %, + 14 %) training. At ventilatory threshold (VT), power output (W) and VO(2) were significantly increased with arm (+ 145 % and + 51 %) and leg (+ 53 % and + 46 %) training. Transfer effects (changes between pre and post tests performed with untrained limbs) were observed: W(p) and VO(2) were not increased in AG while W(p) was increased in LG (+ 11 %). At VT, W and VO(2) were increased with arm (+ 19 % and + 23 %) and leg (+ 33 % and + 46 %) training. For AG and LG the VO(2) expressed in percent of the VO(2) peak was increased (+ 19 % and + 33 %, respectively) and the O(2p) was also increased (+ 30 %) for LG. These results show that SWEET training induced specific and transfer effects. Moreover, the initial level of the subjects, the type and the intensity of the training seem to be the major factors for effective observable transfer effects.

The aim of this study was to determine the hormonal responses, which are dependent on the sleep wake cycle, to strenuous physical exercise. Exercise was performed after different nocturnal regimens: (i) a baseline night preceded by a habituation night; (ii) two nights of partial sleep deprivation caused by a delayed bedtime or by an early awakening; and (iii) two nights of sleep after administration of either a hypnotic compound (10 mg zolpidem) or a placebo. Eight well-trained male endurance athletes with a maximal oxygen uptake of 63.5 +/- 3.8 ml x kg(-1) x min(-1) (mean value +/- s(x)) were selected on the basis of their sleeping habits and their physical training. Polygraphic recordings of EEG showed that both nights with partial sleep loss led to a decrease (P< 0.01) in stage 2 and rapid eye movement sleep. A delayed bedtime also led to a decrease (P < 0.05) in stage 1 sleep. Zolpidem had no effect on the different stages of sleep. During the afternoon after an experimental night, exercise was performed on a cycle ergometer. After a 10-min warm-up, the participants performed 30 min steady-state cycling at 75% VO(2-max) followed by a progressively increased workload until exhaustion. The recovery period lasted 30 min. Plasma growth hormone, prolactin, cortisol, catecholamine and lactate concentrations were measured at rest, during exercise and after recovery. The concentration of plasma growth hormone and catecholamine were not affected by partial sleep deprivation, whereas that of plasma prolactin was higher (P < 0.05) during the trial after an early awakening. Plasma cortisol was lower (P < 0.05) during recovery after both sleep deprivation conditions. Blood lactate was higher (P < 0.05) during submaximal exercise performed after both a delayed bedtime and an early awakening. Zolpidem-induced sleep did not affect the hormonal and metabolic responses to subsequent exercise. Our results demonstrate only minor alterations in the hormonal responses to exercise after partial sleep deprivation.

The changes in circulating concentrations of insulin-like growth factors during exercise have to date remained incomplete in their documentation. Therefore, we examined in 25 healthy athletes the effects of three different durations of three types of exercise – incremental ergometer cycling exercise (ICE), long-distance Nordic ski race (NSR) and a treadmill-simulated soccer game (TSG) lasting 20 min, 3 h, and 2 × 45 min separated by a 15-min half-time rest respectively, on plasma concentrations of growth hormone ([GH]), insulin-like growth factor-1 ([IGF-I]) and its binding proteins 1 and 3 ([IGFBP-1], [IGFBP-3]). Compared to baseline, serum [GH] increased by 15.2-fold after ICE (P < 0.001), 2.9-fold after NSR (P < 0.01) and 4.6-fold after TSG. Serum [IGF-I] rose by 11.9% after ICE (P < 0.001), while it decreased by −14.6% after NSR (P < 0.001) and was unchanged after TSG. Serum [IGFBP-1] was slightly increased (1.7-fold) after ICE (P < 0.01), but increased markedly (11.8-fold) after NSR (P < 0.001) and by 6.3-fold after the second session of TSG (P < 0.01) (it remained unchanged at the end of the first period of TSG, i.e. after 45-min exercise). The [IGFBP-3] increased by 14.7% after ICE (P < 0.001) and by 6% after TSG (P < 0.05) while it did not change after NSR. From our results it would appear that [IGFBP-1] increase to bind free IGF and hinder their insulin-like action during long-term exercise (lasting beyond 45 min). It is suggested that IGFBP-1 might thus contribute both to preventing hypoglycaemic action of IGF and to facilitating glucose uptake by muscle cells when muscle glycogen stores become deplete.

The aim of the study was to investigate the effects of a partial sleep deprivation on a subsequent supramaximal exercise evaluated from the 30 second Wingate test, and on the following recovery. To take into account the active muscle mass, the Wingate test was performed against a constant braking force related to the data of a force-velocity test conducted on a Monark cycle ergometer (Model 814 E with weights) one week before the experimental test. Eight highly trained athletes were enrolled for this study. The changes in ventilatory and metabolic responses were analyzed during and upon completion of physical 30 second exercise, taking place after two nights, in other words, after a reference night and after a night with reduced sleep. Partial sleep deprivation was obtained by delaying bedtime until 3 a.m. The 30 second Wingate test was performed between 9 a.m. and noon the following days, using a Monark ergometer (Model 814 F). The analyses of change scores disclosed that there were no main significant effects for measures of ventilation, lactates and pH(v) levels under the two experimental conditions. The peak power, the mean power output and the peak velocity recorded after partial sleep deprivation were not modified in comparison with the values obtained after the reference night. These findings suggest that acute sleep loss did not contribute to alterations in supramaximal exercise.

The purpose of the study was to compare the cardiovascular, respiratory and metabolic responses to exercise of highly endurance trained subjects after 3 different nights i.e. a baseline night, a partial sleep deprivation of 3 h in the middle of the night and a 0.25-mg triazolam-induced sleep. Sleep-waking chronobiology and endurance performance capacity were taken into account in the choice of the subjects. Seven subjects exercised on a cycle ergometer for a 10-min warmup, then for 20 min at a steady exercise intensity (equal to the intensity corresponding to 75% of the predetermined maximal oxygen consumption) followed by an increased intensity until exhaustion. The night with 3 h sleep loss was accompanied by a greater number of periods of wakefulness (P

Sleep, through its restorative functions, is essential for life. However, lifestyle modifications, sedentary and unhealthy feeding behaviors trigger sleep curtailment and sleep disruption, leading together to weight gain. Obesity is usually associated with obstructive sleep apnea (OSA), and these two diseases both induce metabolic dysfunctions and low-grade systemic inflammation. To the best of our knowledge, no study has assessed the effects of exercise reconditioning and modified food habits on these parameters. The purpose of this work was to assess and compare, from an ancillary study, polysomnographic variables between obese adolescents and normal-weight (NW) controls. In the main study, the effects of a 9-month program (exercise reconditioning, adapted physical activities and modified food habits) on sleep architecture, sleep duration, OSA, biological factors (inflammatory, hormonal, carbohydrates and lipid profiles) and physiological adaptations at exercise were assessed, in order to a better understanding of the roles of cardiorespiratory fitness and sleep disorders on cardio-metabolic health. Thirty-two obese adolescents (age: 14.6 years, BMI z-score: 4.7) were recruited. Every parameters were assessed at admission and post-intervention. Short sleep duration and a high prevalence of OSA (58%) were observed at admission in obese adolescents despite a satisfying sleep architecture, compared with NW controls. Post-intervention, weight loss (11kg) and improved parameters of physiological adaptations at exercise (MAP, VE, VO2peak) were found in every subject and OSA was normalized in 46% of them. Sleep quantity and sleep quality were improved. Decreased C-reactive protein (6.78 vs 10.98 mg/l) and leptin concentrations, and increased adiponectin levels were found, and cardio-metabolic risk (CMR) was decreased. At admission, obesity explains by itself the systemic inflammation whereas the decrease in inflammation, post-intervention, is explained by enhanced cardiorespiratory fitness related to fat-free mass, after controlling for sex, weight loss, change in sleep duration and OSA. Prevention of OSA and metabolic dysfunctions by chronic exercise should be an integral part of the obesity management in youths in order to decrease the risk of cardiovascular morbi-mortality in adulthood; Le sommeil, de par ses fonctions récupératrices, est essentiel à la vie. Pour autant, la modification du mode de vie et des comportements, tant sédentaires que nutritionnels, sont à l’origine d’une altération du sommeil, conduisant ensemble à des situations d’obésité. Cet excès pondéral s’accompagne fréquemment d’un syndrome d’apnées obstructives du sommeil (SAOS). Lorsque ces deux pathologies sont présentes, les troubles métaboliques s’aggravent et sont à l’origine d’une inflammation de bas grade. A notre connaissance, aucune étude ne s’est intéressée aux bénéfices d’un reconditionnement à l’exercice physique combiné à une modification des habitudes alimentaires, en dehors de ceux induits par la perte de poids, sur ces différents paramètres. L’objectif de ce travail de thèse a donc été, à partir d’une étude ancillaire, d’évaluer le sommeil d’adolescents obèses par polysomnographie (PSG) par comparaison à celui de sujets normo-pondérés. Dans l’étude principale, les effets d’un programme de 9 mois (reconditionnement à l’exercice, activités physiques adaptées, rééquilibre alimentaire) ont été évalués sur l’architecture et la durée du sommeil, le SAOS, les différents facteurs biologiques (inflammatoires, hormonaux, profils glucidique et lipidique) et sur les adaptations physiologiques à l’exercice musculaire, afin de mieux comprendre l’implication de l’endurance aérobie et des troubles du sommeil sur la santé cardio-métabolique. Trente-deux adolescents obèses (âge : 14,6 ans, z-score d’IMC= 4 ,7) ont été recrutés. Toutes les variables ont été analysées en pré et post-intervention. Les résultats montrent une durée de sommeil réduite chez les jeunes obèses avec un SAOS, diagnostiqué chez 58% d’entre eux, malgré une architecture du sommeil satisfaisante. En post-intervention, une perte de poids de 11 kg et une amélioration des paramètres d’adaptation à l’exercice maximal (PMA, VE, VO2pic…) ont été rapportées chez tous les sujets, que le SAOS soit encore, ou non, présent. En effet, ce syndrome s’est normalisé chez 46% d’entre eux. Par ailleurs, grâce à l’intervention, le sommeil s’est amélioré (qualité et quantité). Enfin, la protéine C-réactive basale du groupe SAOS, dont les valeurs atteignaient 11mg/l à l’admission, a considérablement diminué, accompagnée d’une baisse de la leptinémie et d’une hausse de l’adiponectinémie, pouvant expliquer le moindre risque cardio-métabolique. Nos résultats démontrent qu’à l’admission, l’inflammation est liée à l’obésité, alors qu’en post-intervention, sa baisse s’explique par l’augmentation de l’endurance aérobie, et ceci indépendamment du sexe, du poids, de la durée de sommeil et du SAOS. Bien que ce dernier n’ait pas été normalisé chez tous les sujets, sa prévention par l’exercice physique ainsi que celle des troubles métaboliques observés dans ces deux pathologies devrait faire partie intégrante de la prise en charge des jeunes obèses en vue d’atténuer le risque de morbi-mortalité cardiovasculaire à l’âge adulte

Sleep, through its restorative functions, is essential for life. However, lifestyle modifications, sedentary and unhealthy feeding behaviors trigger sleep curtailment and sleep disruption, leading together to weight gain. Obesity is usually associated with obstructive sleep apnea (OSA), and these two diseases both induce metabolic dysfunctions and low-grade systemic inflammation. To the best of our knowledge, no study has assessed the effects of exercise reconditioning and modified food habits on these parameters. The purpose of this work was to assess and compare, from an ancillary study, polysomnographic variables between obese adolescents and normal-weight (NW) controls. In the main study, the effects of a 9-month program (exercise reconditioning, adapted physical activities and modified food habits) on sleep architecture, sleep duration, OSA, biological factors (inflammatory, hormonal, carbohydrates and lipid profiles) and physiological adaptations at exercise were assessed, in order to a better understanding of the roles of cardiorespiratory fitness and sleep disorders on cardio-metabolic health. Thirty-two obese adolescents (age: 14.6 years, BMI z-score: 4.7) were recruited. Every parameters were assessed at admission and post-intervention. Short sleep duration and a high prevalence of OSA (58%) were observed at admission in obese adolescents despite a satisfying sleep architecture, compared with NW controls. Post-intervention, weight loss (11kg) and improved parameters of physiological adaptations at exercise (MAP, VE, VO2peak) were found in every subject and OSA was normalized in 46% of them. Sleep quantity and sleep quality were improved. Decreased C-reactive protein (6.78 vs 10.98 mg/l) and leptin concentrations, and increased adiponectin levels were found, and cardio-metabolic risk (CMR) was decreased. At admission, obesity explains by itself the systemic inflammation whereas the decrease in inflammation, post-intervention, is explained by enhanced cardiorespiratory fitness related to fat-free mass, after controlling for sex, weight loss, change in sleep duration and OSA. Prevention of OSA and metabolic dysfunctions by chronic exercise should be an integral part of the obesity management in youths in order to decrease the risk of cardiovascular morbi-mortality in adulthood; Le sommeil, de par ses fonctions récupératrices, est essentiel à la vie. Pour autant, la modification du mode de vie et des comportements, tant sédentaires que nutritionnels, sont à l’origine d’une altération du sommeil, conduisant ensemble à des situations d’obésité. Cet excès pondéral s’accompagne fréquemment d’un syndrome d’apnées obstructives du sommeil (SAOS). Lorsque ces deux pathologies sont présentes, les troubles métaboliques s’aggravent et sont à l’origine d’une inflammation de bas grade. A notre connaissance, aucune étude ne s’est intéressée aux bénéfices d’un reconditionnement à l’exercice physique combiné à une modification des habitudes alimentaires, en dehors de ceux induits par la perte de poids, sur ces différents paramètres. L’objectif de ce travail de thèse a donc été, à partir d’une étude ancillaire, d’évaluer le sommeil d’adolescents obèses par polysomnographie (PSG) par comparaison à celui de sujets normo-pondérés. Dans l’étude principale, les effets d’un programme de 9 mois (reconditionnement à l’exercice, activités physiques adaptées, rééquilibre alimentaire) ont été évalués sur l’architecture et la durée du sommeil, le SAOS, les différents facteurs biologiques (inflammatoires, hormonaux, profils glucidique et lipidique) et sur les adaptations physiologiques à l’exercice musculaire, afin de mieux comprendre l’implication de l’endurance aérobie et des troubles du sommeil sur la santé cardio-métabolique. Trente-deux adolescents obèses (âge : 14,6 ans, z-score d’IMC= 4 ,7) ont été recrutés. Toutes les variables ont été analysées en pré et post-intervention. Les résultats montrent une durée de sommeil réduite chez les jeunes obèses avec un SAOS, diagnostiqué chez 58% d’entre eux, malgré une architecture du sommeil satisfaisante. En post-intervention, une perte de poids de 11 kg et une amélioration des paramètres d’adaptation à l’exercice maximal (PMA, VE, VO2pic…) ont été rapportées chez tous les sujets, que le SAOS soit encore, ou non, présent. En effet, ce syndrome s’est normalisé chez 46% d’entre eux. Par ailleurs, grâce à l’intervention, le sommeil s’est amélioré (qualité et quantité). Enfin, la protéine C-réactive basale du groupe SAOS, dont les valeurs atteignaient 11mg/l à l’admission, a considérablement diminué, accompagnée d’une baisse de la leptinémie et d’une hausse de l’adiponectinémie, pouvant expliquer le moindre risque cardio-métabolique. Nos résultats démontrent qu’à l’admission, l’inflammation est liée à l’obésité, alors qu’en post-intervention, sa baisse s’explique par l’augmentation de l’endurance aérobie, et ceci indépendamment du sexe, du poids, de la durée de sommeil et du SAOS. Bien que ce dernier n’ait pas été normalisé chez tous les sujets, sa prévention par l’exercice physique ainsi que celle des troubles métaboliques observés dans ces deux pathologies devrait faire partie intégrante de la prise en charge des jeunes obèses en vue d’atténuer le risque de morbi-mortalité cardiovasculaire à l’âge adulte

Pédiatrie obesity and its associated diseases hâve become a major public health challenge. However, thé return to daily physical and leisure activities, recommended by most international guidelines, can be difficult for obèse youths, due to low self-esteem, difficulties in integrating groups and poor physical fitness. Overweight combined with sedentarity progressively modify cardio-respiratory exercise tolérance, rendering difficult thé return to exercise and contributing to non-compliance with prescriptions for physical activity. To meet thé growing needs of professionals in thé field of physical activity responsible for thé management of thèse subjects, thé main objective of this doctoral thesis was to validate clinical tools exploring cardiorespiratory capacity in obèse adolescent.A 12 minute walk/run test, an adapted 20m shuttle walk test (starting speed 4 km.b.-1,incréments : 0.5 km.h-1.miir1) and a submaximal exercise test by cycle ergometer with 4 stageswere proposed to calculate indices of cardiorespiratory fitness (D12, Vmax, PMA).Time-varying spectral analysis of heart rate variability was studied to estimate intensitiessubmaximal exercise near ventilatory thresholds.-The "Childhood Obesity Perceived Exertion Scale" (COPE-10) was used to quantify thé intensity of exercise as perceived by thé subjects during exercise.Thèse non-invasive tools, inexpensive, useful in thé évaluation and follow-up of cardiorespiratory fitness in obèse adolescents, can easily be used to develop and personalise adapted re-training programmes in thèse overweight teenagers.; L'obésité pédiatrique et ses pathologies associées sont devenues un problème majeur de santé publique. La reprise des activités physiques quotidiennes et de loisirs, préconisée dans les recommandations internationales, est souvent complexe chez le jeune obèse en raison d'une image de soi dévalorisée, de difficultés d'intégration et d'une faible condition physique. L'excès pondéral, associé à la sédentarité, altère progressivement l'endurance cardiorespiratoire à l'exercice, freinant le retour à une pratique physique régulière et contribuant à la non-observance des prescriptions en activité physique. Pour répondre à un besoin croissant des professionnels de l'activité physique impliqués dans la prise en charge de ces jeunes, l'objectif de ce travail de thèse a été de valider des outils cliniques explorant l'endurance cardiorespiratoire chez l'adolescent obèse :Un test de marche/course de 12 minutes, un test de marche navette adapté sur 20 mètres (4km.h^ incrémenté de 0,5 km.HAmin-1) et un test sous-maximal sur ergocycle en 4 paliers ontpermis de déterminer des indices d'endurance cardiorespiratoire (D12, Vmax, PMA).L'analyse fréquentielle en temps variant de la variabilité de la fréquence cardiaque a permisd'estimer des intensités d'exercice sous-maximales proches des seuils ventilatoires.Le "Childhood Obesity Perceived Exertion Scale" (COPE-10) a permis de quantifier l'intensitéde l'exercice perçue au cours de l'effort.Ces outils non-invasifs et peu coûteux, utiles à l'évaluation initiale et au suivi de la condition physique du jeune obèse, peuvent être facilement utilisés pour concevoir et individualiser des programmes de réentraînement adaptés à ces jeunes.