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Objective The pandemic of obesity in Western countries is mainly due to the high-fat, high-energy diet prevailing there. Obesity-associated metabolic disorders are the consequence of fat mass increase leading to altered adipokine secretion, hyperlipemia, oxidant stress, low-grade inflammation, and eventually glucose intolerance. Yet not all people consuming a Western diet become obese, and the question is raised whether these people are also at risk of developing metabolic disorders. Methods Glucose tolerance, lipid profile, and oxidant and inflammation status were investigated longitudinally in lean Gottingen minipigs receiving for 16 weeks either a normal diet (ND), a Western diet (WD), or a Western diet supplemented with a whey protein isolate (WPI) rich in α-lactalbumin known to improve glucose tolerance. ND and WD were supplied isoenergetically. Results Lean minipigs fed WD displayed glucose intolerance and altered lipid profile after 6 weeks of diet but no inflammation or oxidative stress. Supplementation with WPI alleviated glucose intolerance by improving insulin secretion, but not lipid profile. Conclusions Western diet consumption is deleterious for glucose tolerance even in the absence of fat mass accretion, and dyslipemia is a major determinant for this metabolic dysfunction. Stimulating insulin secretion with a WPI is an effective strategy to improve glucose tolerance.

Background: The obesity-related factors in adolescents differ from one country to another. In Lebanon, those factors are still undetermined. Therefore, our purpose is to investigate the main determinants of overweight and obesity in Lebanese adolescents and to assess gender-specific differences. Methods: In this cross-sectional epidemiological study, 1000 Lebanese adolescents were recruited to determine obesity-related factors: birth weight, weight at 5 and 10-year-old children, feeding pattern, only child or first born status, puberty characteristics, lifestyle [nutrition, sedentary behaviors, and physical activity], school grades, family obesity, obesity-related diseases, place of residence, and socio-economic and professional status of parents. Results: Multiple regressions show that puberty obesity, lifestyle, family obesity and family status, and childhood feeding pattern are consecutively the major factors to adolescents’ obesity. Contrary to Western countries, overweight and obese Lebanese adolescents belong to a high socioeconomic class, and they do practice more physical and leisure activities. This paradox is more obvious in boys (having a higher socio-economic status compared to girls, boys are more affected by overweight and obesity caused by behavioral problems and this despite their more frequent physical leisure activities). On the contrary, girls’ obesity is more associated with family obesity rather than behavior disorders. Conclusion: Lebanese adolescents’ obesity is related to many behavior disorders especially in boys. Moreover, their physical practice is not sufficient to overcome their excessive sedentary behaviors and nutritional mistakes.

Ageing causes a progressive decline in skeletal muscle mass that may lead to decreased strength and functionality. The term sarcopenia is especially used to characterise this geriatric syndrome. Numerous conditions and behaviours are considered to accelerate the progression of sarcopenia such as chronic diseases, malnutrition and physical inactivity. As people in modern countries are more and more sedentary, the impact of physical inactivity on the prevalence of sarcopenia might be more and more important in the future. In this review, we discuss how reactive oxygen species (ROS) could mediate the effects of lifelong inactivity in the onset and progression of age-related sarcopenia. Although the cellular mechanisms responsible for muscle ROS production are not necessarily the same, both inactivity and ageing are indeed known to increase basal ROS concentrations in skeletal muscle. New data and literature review are provided showing that chronic ROS overproduction induced by physical inactivity may exacerbate the activation of some redox-sensitive signalling pathways involved in age-related sarcopenia. We also address the scientific evidences implicating the role of ROS overproduction in the precocious failure of aged muscles to activate intracellular signalling responses to contractions.

Resume Introduction Le but de cette etude est de determiner l’effet de huit semaines d’entrainement intense en endurance sur l’expression des recepteurs β1- et β2-adrenergiques cardiaques chez des rats diabetiques et controles. Synthese des faits L’expression du recepteur β1-adrenergique des rats diabetiques sedentaires est significativement diminuee ( p p Conclusion Un entrainement intense en endurance de huit semaines au cours du diabete induit une diminution de l’expression du recepteur β2-adrenergique, qui pourrait constituer un mecanisme de protection du cœur diabetique contre une sur-stimulation catecholaminergique.

We investigated the effect of a moderate mutivitamin and mineral supplementation containing mainly vitamin C (150.0 mg.day(-1)), vitamin E (24.0 mg.day(-1)) and beta-carotene (4.8 mg.day(-1)) prior to and during an extreme running competition -the Marathon des Sables (MDS)- that consisted of six long races in the desert.Seventeen athletes participated in our double blind, placebo-controlled study. Blood samples were collected prior to the supplementation i.e. three weeks before the competition (D-21), two days prior to the MDS (D-2), after the third race (D3) and at the end of the competition (D7). Erythrocyte antioxidant enzyme activity (glutathione peroxidase (GPx), superoxide dismutase (SOD)), erythrocyte glutathione level (GSH), plasma non-enzymatic antioxidant status (uric acid, vitamin C, alpha-tocopherol, retinol, beta-carotene), markers of plasma lipid peroxidation (thiobarbituric reactive substances (TBARS)), reactive carbonyl derivatives (RCD) and membrane damage (creatine kinase and lactate dehydrogenase activities) were measured.In both groups, GSH levels, uric acid levels and membrane damage significantly increased during the competition while SOD activity significantly decreased. In Supplemented group, plasma alpha-tocopherol, beta-carotene and retinol levels significantly increased after three weeks of supplementing. In contrast to Placebo group, alpha-tocopherol, vitamin C and retinol levels were significantly affected by the competition in Supplemented group. Moreover, no increase in TBARS was observed in Supplemented group during the competition, whereas TBARS significantly increased at D3 in the placebo group.The moderate multivitamin-mineral supplementation prevented the transient increase in TBARS levels during this extreme competition.

Background: Exercise testing has become a valuable help for the physician to examine the influence of recommended exercise training on physical fitness. However, the question as to how diabetic prepubertal children differ from their non-diabetic peers in their performance capacity has only partial and sometimes conflicting answers in the literature. Aim and methods: The aim of the current study was thus to evaluate aerobic fitness during an incremental submaximal test (measure of the Physical Working Capacity 170 (PWC 170 )) in 17 well-controlled prepubertal insulin-dependent diabetic boys aged 8.5-13 y. Eighteen healthy prepubertal boys matched for age, body size and physical activity served as controls. Part of the method was to check capillary blood glucose level in the diabetic patients and in nine of the healthy subjects throughout the exercise. Results: From this experiment it appeared that the level of physical fitness was similar in diabetic and healthy boys (PWC 170 2.28±0.09 vs 2.37±0.13 W.kg -1 ). While glucose homeostasis was well maintained in the healthy group, diabetic children showed a marked fall in blood glucose during the exercise. In addition, the PWC 170 level correlated significantly with the estimate of energy expenditure attributed to vigorous activities in the diabetic boys. Conclusion: By studying the responses to incremental exercise there is growing evidence that normal physical fitness is preserved in diabetic prepubertal boys given appropriate involvement in physical activity.

International audience; In the literature, the terms physical inactivity and immobilization are largely used as synonyms. The present review emphasizes the need to establish a clear distinction between these two situations. Physical inactivity is a behavior characterized by a lack of physical activity, whereas immobilization is a deprivation of movement for medical purpose. In agreement with these definitions, appropriate models exist to study either physical inactivity or immobilization, leading thereby to distinct conclusions. In this review, we examine the involvement of oxidative stress in skeletal muscle insulin resistance and atrophy induced by, respectively, physical inactivity and immobilization. A large body of evidence demonstrates that immobilization-induced atrophy depends on the chronic overproduction of reactive oxygen and nitrogen species (RONS). On the other hand, the involvement of RONS in physical inactivity-induced insulin resistance has not been investigated. This observation outlines the need to elucidate the mechanism by which physical inactivity promotes insulin resistance

International audience; Oxidative stress and inflammation are involved in the development of type 1 diabetes and its complications. Because two compounds found in soy, that is, isoflavones and alpha-galactooligosaccharides, have been shown to exert antioxidant and anti-inflammatory effects, this study aimed to assess the effects of a dietary supplement containing these two active compounds, the fermented soy permeate (FSP). We hypothesized that FSP would be able to reduce in vivo oxidative stress and inflammation in streptozotocin (STZ)-induced type 1 diabetic rats. Thirty male Wistar rats were divided into the control placebo, diabetic placebo, and diabetic FSP-supplemented groups. They received daily, by oral gavage, water (placebo groups) or diluted FSP (0.1 g/day; FSP-supplemented group). After 3 weeks, glycemic regulation (glycemia and fructosamine level); the plasma level of carboxymethyllysine (CML), a marker of systemic oxidative stress in diabetes; and the plasma levels of inflammatory markers (CRP, IL-1β, IL-6, and uric acid) were evaluated. Markers of oxidative damage (isoprostanes and GSH/GSSG), antioxidant enzymatic activity (SOD and GPX), and Mn-SOD content were determined in skeletal muscle (gastrocnemius). Diabetic placebo rats exhibited higher CML levels, lower SOD and GPX activities, and decreased Mn-SOD contents. FSP supplementation in diabetic animals normalized the CML and antioxidant enzymatic activity levels and tended to increase Mn-SOD expression. The markers of inflammation whose levels were increased in the diabetic placebo group were markedly decreased by FSP (IL-1β: -75%, IL-6: -46%, and uric acid: -17%), except for CRP. Our results demonstrate that FSP exhibited antioxidant and anti-inflammatory properties in vivo in STZ-induced diabetic rats.

Aim The aim of this work was to study regulation of the calcineurin antagonist, Regulator of Calcineurin1 protein (RCAN1), in rat skeletal muscles following exhaustive physical exercise, which is a physiological modulator of oxidative stress. Results Three skeletal muscles, namely Extensor Digitorum Longus (EDL), gastrocnemius, and soleus were investigated. Exhaustive exercise increased RCAN1-4 protein levels in EDL and gastrocnemius, but not in soleus. Protein oxidation as an index of oxidative stress was increased in EDL and gastrocnemius, but remained unchanged in soleus. However lipid peroxidation was increased in all three muscles. CuZnSOD and catalase protein levels were increased at 3Hr post exercise in soleus, while they remained unchanged in EDL and gastrocnemius. Calcineurin enzymatic activity declined in EDL and gastrocnemius but not in soleus, and its protein expression was decreased in all three muscles. The level of PGC1-α protein remained unchanged whereas the protein expression of transcription factor NFATc4 was decreased in all three muscles. Adiponectin expression was increased in all three muscles. Conclusion RCAN1-4 expression in EDL and gastrocnemius muscles was augmented by the oxidative stress generated from exhaustive exercise. We propose that increased RCAN1-4 expression, and the signal transduction pathways it regulates, represent important components of the physiological adaptation to exercise-induced oxidative stress.

In preclinical models, exercise training (ET) or pomegranate juice (PJ) prevents prostate cancer progression. Here, we hypothesized that physical exercise combined with antioxidants could induce synergistic effects through oxidative stress modulation. Forty male Copenhagen rats with prostate tumors were divided into four groups: control, PJ, ET, and PJ+ET. Rats from the PJ group consumed 750 µl of PJ daily, rats from the ET group ran on a treadmill 5 days per week, and PJ+ET rats received the combined treatment. Each week, tumor growth was evaluated. After 4 weeks of treatment, the rats were euthanized and blood, muscles, and tumors were collected. Tumor Ki67, extracellular signal-regulated kinase (ERK) activation, Bcl-2 expression, and enzymatic and nonenzymatic antioxidant defenses, as well as oxidative stress markers (oxidized base, lipid peroxidation, protein carbonylation), were measured. PJ or ET significantly decreased prostate tumor proliferation (Ki67 staining, p

Exercise testing has become a valuable help for the physician to examine the influence of recommended exercise training on physical fitness. However, the question as to how diabetic prepubertal children differ from their non-diabetic peers in their performance capacity has only partial and sometimes conflicting answers in the literature.The aim of the current study was thus to evaluate aerobic fitness during an incremental submaximal test (measure of the Physical Working Capacity 170 (PWC170)) in 17 well-controlled prepubertal insulin-dependent diabetic boys aged 8.5-13 y. Eighteen healthy prepubertal boys matched for age, body size and physical activity served as controls. Part of the method was to check capillary blood glucose level in the diabetic patients and in nine of the healthy subjects throughout the exercise.From this experiment it appeared that the level of physical fitness was similar in diabetic and healthy boys (PWC170 2.28+/-0.09 vs 2.37+/-0.13 W x kg(-1)). While glucose homeostasis was well maintained in the healthy group, diabetic children showed a marked fall in blood glucose during the exercise. In addition, the PWC170 level correlated significantly with the estimate of energy expenditure attributed to vigorous activities in the diabetic boys.By studying the responses to incremental exercise there is growing evidence that normal physical fitness is preserved in diabetic prepubertal boys given appropriate involvement in physical activity.

The influence of gender on the glucose response to exercise remains contradictory. Moreover, to our knowledge, the glucoregulatory responses to anaerobic sprint exercise have only been studied in male subjects. Hence, the aim of the present study was to compare glucoregulatory metabolic (glucose and lactate) and hormonal (insulin, catecholamines and estradiol only in women) responses to a 30-s Wingate test, in physically active students. Eight women [19.8 (0.7) years] and eight men [22.0 (0.6) years] participated in a 30-s Wingate test on a bicycle ergometer. Plasma glucose, insulin, and catecholamine concentrations were determined at rest, at the end of both the warm-up and the exercise period and during the recovery (5, 10, 20, and 30 min). Results showed that the plasma glucose increase in response to a 30-s Wingate test was significantly higher in women than in men [0.99 (0.15) versus 0.33 (0.20) mmol l(-1) respectively, P0.05]. Plasma insulin concentrations peaked at 10 min post-exercise and the increase between this time of recovery and the end of the warm-up was also significantly higher in women than in men [14.7 (2.9) versus 2.3 (1.9) pmol l(-1) respectively, P0.05]. However, there was no gender difference concerning the catecholamine response. The study indicates a gender-related difference in post-exercise plasma glucose and insulin responses after a supramaximal exercise.

In this study we investigated whether plasma catecholamine responses to the Wingate test are affected by the intensity of training in endurance-trained subjects. To do this we compared plasma adrenaline (A) and noradrenaline (NA) concentrations in response to a Wingate test in three different groups: specialist middle-distance runners (MDR) in 800-m and 1,500-m races, specialist long-distance runners (LDR) 5,000-m and 10,000-m races, and untrained subjects (UT). The maximal power ( W(max)) and the mean power ( W) were determined from the Wingate test. Blood lactate (La), plasma A and NA concentrations were analysed at rest (La(0), A(0) and NA(0)), immediately at the end of the exercise (A(max )and NA(max)) and after 5 min recovery (La(max), A(5) and NA(5)). The ratio A(max)/NA(max )was considered as an index of the adrenal medulla responsiveness to the sympathetic nervous activity. At the end of the test, W(max) and W were similar in the three groups but La(max) was significantly greater in MDR compared to LDR and UT [15.2 (2.2) mmol l(-1), 11.7 (3.1) mmol l(-1), 11.6 (1.6) mmol l(-1), respectively, for MDR, LDR and UT; mean (SD)]. Concerning the plasma catecholamine concentrations in response to exercise, MDR and LDR A(max) values [3.73 (1.53) nmol l(-1), 3.47 (0.74) nmol l(-1), respectively, for MDR and LDR] were significantly greater than those of UT [1.48 (0.32) nmol l(-1)] who also exhibited the lowest NA(max) values [11.09 (6.58) nmol l(-1)] compared to MDR and LDR [20.43 (3.51) nmol l(-1); 15.85 (4.88) nmol l(-1), respectively, for MDR and LDR]. However, no significant differences were observed between the two trained groups either for A(max) or NA(max.) These results suggest that long-term endurance training can enhance plasma catecholamine concentrations in response to supramaximal exercise. However, as there were no significant differences between MDR and LDR A(max) and NA(max) values, the effect of the intensity of training remains to be clarified.

Supramaximal exercises are well known to induce a severe stress on the adrenal medulla and nervous sympathetic system. This stress induces increased plasma catecholamines concentrations. The responses of catecholamines to supramaximal exercises in women are still not well characterized and have been studied mostly in trained subjects. Hence the aim of the present study was to evaluate plasma catecholamine responses to a Wingate test in young and untrained women (n = 6) and men (n = 7). Venous plasma catecholamine concentrations were determined by HPLC, at rest, at the end of the warm-up and of the exercise, and during recovery (5, 10, 20, and 30 mn). Our results failed to show any significant difference in resting catecholamine concentrations ([A]p: 0.41 ± 0.05 vs. 0.45 ± 0.05 nmolúL−1; [NA]p: 3.28 ± 0.68 vs. 2.58 ± 0.26 nmolúL−1), kinetics, and maximal plasma catecholamine concentrations (Amax: 4.47 ± 1.08 vs. 3.31 ± 0.63 nmolúL−1; NAmax: 18.05 ± 1.11 vs. 14.01 ± 2.02 nmolúL−1) in response to the Wingate test between women and men, respectively. The Amax/NAmax ratio used as an index of adrenal medulla sensitivity to sympathetic input was also similar between genders. In conclusion, this study was able to demonstrate, in untrained subjects, that gender did not alter the sympatho-adrenergic response induced by a severe stress. Key words: stress hormones, gender, luteal phase

To examine hormonal and metabolic effects of an oral challenge in glucose (≈ 16 g), 15 prepubertal girls performed a 30-min ergocycle test at 60% of Wmax. Among them, 8 ingested an oral glucose challenge between 2 and 3 min after the beginning of the exercise whereas the other 7 girls received no fluid intake. Plasma glucose is influenced by the oral challenge, as the values obtained at the 15th and 30th min are higher than those of the control group. Plasma FFA, catecholamines, and insulin are not significantly modified by the oral challenge. Therefore, it seems that a challenge in glucose at the beginning of a prolonged exercise could avoid a fall in plasma glucose.

Resume Objectif. – Ce travail a etudie l’influence du type d’entrainement (en sprint ou en endurance) sur la variation du volume plasmatique (ΔPV) chez des sujets masculins en reponse au Wingate-test. Methode. – Sept specialistes de sprint (S) (20,9 ± 0,6 ans), 7 endurants (E) (20,9 ± 0,8 ans) et 7 non entraines (NE) (21,4 ± 0,5 ans) de sexe masculin ont participe a cette etude. L’hematocrite et la lactatemie ont ete mesures au repos, a l’arret de l’exercice et apres 5, 10, 20 et 30 min de recuperation. La ΔPV est determinee a partir de la variation de l’hematocrite. Resultats. – Comme attendu, lors de l’epreuve de Wingate, le groupe S developpe des puissances significativement superieures, en valeurs absolues et relatives (rapportees au kg de poids ou au kg de masse maigre), a celles des groupes E et NE. Les lactatemies les plus elevees sont observees chez S (18,1 ± 1,2 mmol l–1) et les valeurs les plus faibles chez E (13,4 ± 0,9 mmol l–1) et NE (14,2 ± 1,1 mmol l–1). L’epreuve de Wingate s’accompagne d’une chute significative du volume plasmatique qui atteint en moyenne a l’arret immediat de l’exercice 18,3 % chez S, 10,2 % chez E et 7,9 % chez NE. Cette chute est significativement plus importante a l’arret de l’exercice et apres 5 minutes de recuperation chez S par rapport aux 2 autres groupes E et NE. Conclusion. – En conclusion, ce travail montre que la chute du volume plasmatique induite par l’epreuve de Wingate est beaucoup plus importante chez les specialistes de sprint que chez les specialistes d’endurance ou les non entraines. Les facteurs responsables de ce resultat restent a preciser.

It has been well demonstrated that the principal factor responsible for oxidative damage during exercise is the increase in oxygen consumption. However, other theoretical factors (acidosis, catecholamine autoxidation, ischemia-reperfusion syndrome, etc.) that are known to induce, in vitro, oxidative damage may also be operative during short-term supramaximal anaerobic exercise. Therefore, we hypothesized that short-term supramaximal anaerobic exercise (30-s Wingate test) could induce an oxidative stress. Lipid peroxidation markers [serum lipid radical production detected by electron spin resonance (ESR) spectroscopy and plasma malondialdehyde (MDA) levels detected by the thiobarbituric acid reactive substances (TBARS) method], as well as erythrocyte antioxidant enzyme activities [glutathione peroxidase (GPx), superoxide dismutase (SOD)] and erythrocyte glutathione (GSH) levels, were measured at rest, after the Wingate test and during the 40 min of recovery. The recovery of exercise was associated with a significant increase (x2.7) in lipid radical production detected by ESR spectroscopy, as well as with changes in the erythrocyte GSH level (-13.6%) and SOD activity (-11.7%). The paradoxical decrease in plasma TBARS (-23.7%) which was correlated with the peak power developed during the Wingate test ( r=-0.7), strongly suggests that such exercise stimulates the elimination of MDA. In conclusion, this study demonstrates that short-term supramaximal anaerobic exercise induces an oxidative stress and that the plasma TBARS level is not a suitable marker during this type of exercise.

Botcazou Maïtel, Zouhal Hassane, Jacob C., Gratas-Delamarche Arlette, Berthon Paul, Monnier M., Bentué-Ferrer Danièle, Delamarche Paul. Entraînement anaérobie et réponses plasmatiques en catécholamines, glucose et insuline à l'exercice supramaximal : étude longitudinale. In: Les Cahiers de l'INSEP, n°34, 2003. Expertise et sport de haut niveau. pp. 375-379.

Resume Objectif – Nous avons etudie, dans ce travail, la cinetique de la lactatemie lors d'une seance de sprint sur piste. Sujets et methode – Ont participe a cette etude cinq sprinters de sexe masculins de niveau national. Ils ont realise des repetitions de 50 metres a vitesse maximale sur piste. Resultats – La lactatemie augmente significativement des les premiers sprints, elle passe d'une valeur de fin d'echauffement de 3,9±0,1 mmol.l−1 a des concentrations de l'ordre de 14,0±3,0 mmol.l−1 observees apres le troisieme sprint. Discussion et conclusion – Nos resultats confirment ainsi le fait que la glycolyse anaerobie est sollicitee d'une maniere importante et preponderante des les premieres secondes du sprint meme si celui-ci dure moins de sept secondes. Les entraineurs de sprint doivent donc prendre en compte ces nouvelles donnees lorsqu'ils mettent en place des programmes d'entrainement visant a developper les qualites dites anaerobies alactiques de leurs athletes.

International audience; Abstract In type 1 diabetic subjects, hyperglycemia-induced oxidant stress (OS) plays a central role in the onset and development of diabetes complications. This study aimed to assess the benefits of an endurance training program and insulin therapy, alone or in combination, on the glycemic regulation, markers for OSand antioxidant system in diabetic rats. Forty male Wistar rats were divided into diabetic (D), insulin-treated diabetic (D-Ins), diabetic trained (D-Tr), or insulin-treated diabetic trained (D-Ins+ Tr) groups. An additional healthy group served as control group. Insulin therapy (Lantus, insulin glargine, Sanofi) and endurance training (a treadmill run of 60 min/day, 25 m/min, 5 days/week) were initiated 1 week after streptozotocin-induced diabetes (45 mg/kg) and lasted for 8 weeks. At the end of the protocol, blood glucose and fructosamine levels, markers for skeletal muscle OS (CML, isoprostanes, GSH/GSSG) and antioxidant system (SOD and GPx activity, ORAC) were assessed. In diabetic rats, the glycemic control was altered and OS marker levels were increased, while the antioxidant system activity remained unchanged. Insulin treatment improved the glycemic regulation, the pro-antioxidant statusand contributed to the reduction of OS marker levels. Endurance training decreased OS marker levels without improving the antioxidant enzyme activity. Endurance training and insulin therapy acted independently (by different ways), but their association prolonged the insulin action and allowed a better adaptation of the antioxidant system. To conclude, our results demonstrate that combination of insulin treatment and endurance training leads to greater benefits on the glycemic regulation and oxidant status.

The aim of our study was to elucidate the role of growth hormone (GH) replacement therapy in three of the main mechanisms involved in sarcopenia: alterations in mitochondrial biogenesis, increase in oxidative stress, and alterations in protein balance. We used young and old Wistar rats that received either placebo or low doses of GH to reach normal insulin-like growth factor-1 values observed in the young group. We found an increase in lean body mass and plasma and hepatic insulin-like growth factor-1 levels in the old animals treated with GH. We also found a lowering of age-associated oxidative damage and an induction of antioxidant enzymes in the skeletal muscle of the treated animals. GH replacement therapy resulted in an increase in the skeletal muscle protein synthesis and mitochondrial biogenesis pathways. This was paralleled by a lowering of inhibitory factors in skeletal muscle regeneration and in protein degradation. GH replacement therapy prevents sarcopenia by acting as a double-edged sword, antioxidant and hypertrophic.

The purpose of this study was to determine the effect of aging and training on the adrenaline (A) and noradrenaline (NA) responses during the Wingate-test in three age groups of subjects: 21 year old untrained subjects (21U), 21 year old endurance trained (21T) (national elite runners), 34 year old endurance trained (34T) (national elite runners). Performances during the test were judged using the usual parameters of peak power (W max ) and mean power (W) expressed in absolute or relative values. A and NA responses were measured at rest (A 0 and NA 0 ) immediately at the end of the exercise (A max and NA max ) and after 5 minutes recovery (A 5 and NA 5 ). Plasma maximal lactate (La max ) was determined 3 minutes after the end of the exercise. W max , W and La max were always significantly lower in 34T compared to 21T and 21U. The catecholamine responses were similar in 21T and 21U. Inversely, a significantly lower value of A max was observed in 34T (2.01 ± 0.5 nmol ×l -1 ) compared to 21U (3.62 ± 0.3 nmol × l -1 ) associated with a significantly higher value of NA max in 34T versus 21T and 21U. Thus, the A max /NA max ratio was found to be significantly lower in the older subjects versus both 21T and 21U. All these findings indicated that endurance training did not affect the sympathoadrenergic responses to a supramaximal exercise and suggested that only one decade may reduce the capacity of the medulla to secrete adrenaline and therefore the adrenal medulla responsiveness to the sympathetic nervous activity.

Resume Objectifs L'objet de cette etude etait de determiner les effets d'une charge orale en glucose (0,5 g.kg−1) sur les reponses metaboliques (glucose, acides gras non esterifies) et hormonales (insuline, catecholamines) lors d'un exercice sur ergocycle (30 minutes a 60 % de O2max) chez huit petites filles prepuberes (9,7±0,4 ans) et huit femmes adultes (21,5±0,9 ans). Methodes L'ingestion de glucose a lieu entre la 2e et la 3e minute de l'exercice. Des echantillons ont ete preleves sur sang veineux en position assise sur le cycloergometre ainsi qu'aux 3e, 5e, 10e, 15e et 30e minutes de l'exercice et apres 30 minutes de recuperation. Resultats Durant l'exercice, les concentrations plasmatiques de glucose etaient superieures chez la petite fille. Les valeurs absolues et l'evolution de l'insulinemie etaient strictement identiques dans les deux groupes. Les concentrations de noradrenaline durant l'exercice etaient semblables dans les deux groupes, alors que les concentrations d'adrenaline etaient inferieures chez l'enfant. Le rapport glucose/insuline, utilise comme indicateur de la sensibilite a l'insuline, etait toujours plus eleve chez la petite fille. Conclusion Nos resultats indiquent une plus faible tolerance au glucose durant l'exercice chez la petite fille prepubere. Une relative insulinoresistance, bien connue au repos en periode peripubertaire, est ici envisagee a l'exercice et pourrait engendrer une meilleure utilisation des graisses chez la petite fille, comme le suggerent les valeurs significativement plus elevees en acides gras non esterifies plasmatiques.

Resume Introduction. Les effets du lactate face au stress oxydatif de l'exercice sont controverses, notamment in vivo car difficiles a dissocier des effets de l'acidose concomitante. Nous avons donc teste l'effet de l'ion lactate sur la production de radicaux libres in vitro. Methode et resultats. Deux methodes ont ete utilisees: d'une part le dosage par chromatographie du malondialdehyde, marqueur de la lipoperoxydation d'hepatocytes de rats en culture et, d'autre part, la resonance paramagnetique electronique, qui permet de quantifier la production de radicaux libres, en presence du lactate dissous soit en solution aqueuse soit plasmatique. On observe dans le premier cas une inhibition significative de la production de malondialdehyde a partir de 15 mM de lactate et un pourcentage de piegeage significatif de l'anion superoxyde pour toutes les concentrations de lactate dissous en solution aqueuse et plasmatique. Conclusion. Cette etude montre que le lactate exerce in vitro un effet antioxydant.

Resume Objectif L'objectif de cette etude a ete d'evaluer la consommation journaliere de calcium d'une population sportive mixte et de determiner s'il existe un lien entre cette consommation de calcium et la survenue de fractures de fatigue. Methode L'apport journalier de calcium a ete evalue a l'aide d'un autoquestionnaire. Des questions sur le type et la quantite hebdomadaire d'entrainement y etaient egalement incluses et, pour les femmes, des donnees sur leurs cycles menstruels et la prise ou non de contraceptifs oraux. Resultats La frequence des fractures de fatigue etait de 13,8 %, avec un pourcentage plus eleve chez les femmes que chez les hommes (p Conclusion II n'apparait pas de relation directe entre l'apport de calcium et les fractures de fatigue chez les sportifs interroges. La presence d'un desequilibre hormonal, souvent associe a une pratique physique intensive, serait un des facteurs determinants de la survenue de fractures de fatigue, en tous cas chez la femme.

Resume Objectifs. Cette etude a pour objet de comparer la reponse sympathoadrenergique, a l'exercice supramaximal (test de Wingate), chez des coureurs a pied des deux sexes de niveau national. Sujets et methodes. Treize sujets volontaires ont participe a cette experimentation, six de sexe masculin (groupe 1) (21,0 ± 1,0 ans) et sept de sexe feminin (groupe 2) (19,1 ± 0,7 ans), de meme niveau de competition (national) et apparies sur le niveau de consommation maximale d'oxygene ( V . O 2 max ⁡ ) rapportee au kilogramme de masse maigre. Resultats et discussion . Exprimees en valeurs absolues ou relatives, la puissance pic (PPic) et la puissance moyenne ( W ¯ ) determinees lors du test de Wingate sont significativement superieures dans le groupe 1 par rapport au groupe 2. Pourtant, les reponses en lactate (La), en adrenaline (A) et en noradrenaline (NA) mesurees au repos (La 0 , A 0 et NA 0 ), a l'arret immediat de l'exercice (A max et NA max ) et apres 5 minutes de recuperation (La max , A 5 et NA 5 ) ne different pas statistiquement entre les deux groupes. Conclusions. Ces resultats indiquent que la reponse sympathoadrenergique a l'exercice supramaximal est similaire chez les endurants des deux sexes a meme niveau d'entrainement.

Resume Objectif Etudier l'influence d'un marathon sur la consommation maximale d'oxygene (VO2max) et la vitesse maximale aerobie (VMA) chez neuf marathoniens (niveau national meilleur temps : 153 ± 14 minutes). Methode Un test triangulaire de mesure de la VO2max a ete realise sur tapis roulant chez neufs marathoniens six jours avant (j–6), 3 et 11 jours apres (j+3 et j+11) un marathon. Resultats et conclusion Aucune difference significative n'apparait entre les trois jours concernant la VO2max, la FCrepos, la FCmax, la lactatemie et la VMA ce qui suggere fortement que le niveau de pratique influence la capacite ainsi que la vitesse de recuperation postmarathon.

Resume Introduction. – Ce travail compare les apports nutritionnels en vitamines antioxydantes aux apports nutritionnels conseilles chez des athletes engages dans une epreuve de course extreme. L'apport energetique total et la repartition en macronutriment sont egalement mesures. Synthese des faits. – L'apport en vitamine E est insuffisant pour 95 % des athletes interroges et 22 % d'entre eux ont un apport insuffisant en vitamine C, β-carotene et equivalent retinol. L'apport energetique total est egalement faible (145,4 ± 10,6 kJ/kg par jour). Conclusion. – Les athletes etudies ont une insuffisance d'apport en vitamines antioxydantes pouvant s'expliquer, en partie, par un apport energetique total faible.

Resume Introduction La production d'oxyde nitrique (NO) augmente lors d'exercices aerobies. Plusieurs facteurs (stress de cisaillement, catecholamines et hypoxie) connus pour activer une production accrue de NO sont reunis a l'exercice de sprint. Notre objectif a ete de mesurer dans le sang les produits stables derives du NO en reponse a l'epreuve de Wingate. Synthese des faits Un exercice de sprint augmente la concentration plasmatique de produits derives du NO d'environ 25 % chez des sujets actifs des deux sexes. Conclusion L'augmentation de produits derives du NO est inferieure a celle observee lors d'exercices aerobies et ne differe pas entre hommes et femmes.

Resume Objectif. – Evaluer la performance lors d'un Wingate chez 14 jeunes femmes non entrainees avec contraceptifs oraux (CO+) ou sans (CO–), en debut et fin de cycle menstruel. Methodes et resultats. – Quelque soit le groupe etudie, les puissances pic (PP) et moyenne (PME), l'indice de fatigabilite (IF) et la lactatemie ne different pas entre le debut (j5–j9) et la fin du cycle (j19–j27). Comparees aux CO–, les femmes CO+ sont plus grandes avec une masse maigre superieure et developpent une plus grande PME. Cette difference disparait apres ajustement par le poids et la masse maigre. Conclusion. – Ces resultats suggerent que le cycle hormonal ou la prise d'un contraceptif oral n'affecte pas la performance mesuree lors d'un test de Wingate.

International audience; Epidemiological data indicate that physical inactivity, a main factor of global energetic imbalance, is involved in the worldwide epidemic of obesity and metabolic disorders such as insulin resistance. Although the complex pathogenesis of insulin resistance is not fully understood, literature data accumulated during the past decades clearly indicate that the activation of the oxidative-inflammatory loop plays a major role. By activating the oxidative-inflammatory loop in insulin-sensitive tissues, fat gain and adipose tissue dysfunction likely contribute to induce insulin resistance during chronic and prolonged physical inactivity. However, in the past years, evidence has emerged showing that early insulin resistance also occurs after very short-term exposure to physical inactivity (1-7 days) without any fat gain or energetic imbalance. The possible role of liver disturbances or endothelial dysfunction is suggested, but further studies are necessary to really conclude. Inactive skeletal muscle probably constitutes the primary triggering tissue for the development of early insulin resistance. In the present review, we discuss on the current knowledge about the effect of physical inactivity on whole-body and peripheral insulin sensitivityand how local inflammation and oxidative stress arising with physical inactivity could potentially induce insulin resistance. We assume that early muscle insulin resistance allows the excess nutrients to shift in the storage tissues to withstand starvation through energy storage. We also consider when chronic and prolonged, physical inactivity over an extended period of time is an underestimated contributor to pathological insulin resistance and hence indirectly to numerous chronic diseases.

Superoxide (O 2 ·− ) overproduction, by decreasing the nitric oxide (·NO) bioavailability, contributes to vascular complications in type 1 diabetes. In this disease, the vascular O 2 ·− can be produced by the NADPH oxidase (NOX), nitric oxide synthase (NOS), and xanthine oxidase (XO). This study aimed to determine the contribution of each enzymatic pathway in hyperglycemia-induced O 2 ·− overproduction, and the effects of an endurance training program and insulin therapy, associated or not, on the O 2 ·− production (amount and related enzymes) in diabetic rats. Forty male Wistar rats were divided into diabetic (D), diabetic treated with insulin (D-Ins), diabetic trained (D-Tr), or diabetic insulin-treated and trained (D-Ins + Tr) groups. An additional healthy group was used as control. Insulin therapy (Glargine Lantus, Sanofi) and endurance training (treadmill run: 60 min/day, 25 m/min, 5 days/week) started 1 week after diabetes induction by streptozotocin (45 mg/kg), and lasted for 8 weeks. At the end of the protocol, the O 2 ·− production in aorta rings was evaluated by histochemical analyses (DHE staining). Each production pathway was studied by inhibiting NOX (apocynin), NOS (L-Name), or XO (allopurinol) before DHE staining. Diabetic rats exhibited hyperglycemia-induced O 2 ·− overproduction, resulting from NOX, NOS, and XO activation. Insulin therapy and endurance training, associated or not, decreased efficiently and similarly the O 2 ·− overproduction. Insulin therapy reduced the hyperglycemia and decreased the three enzymatic pathways implicated in the O 2 ·− production. Endurance training decreased directly the NOS and XO activity. While both therapeutic strategies activated different pathways, their association did not reduce the O 2 ·− overproduction more significantly.

International audience; Exercise is essential into the therapeutic management of diabetic patients, but their level of exercise tolerance is lowered due to alterations of glucose metabolism. As soy isoflavones have been shown to improve glucose metabolism, this study aimed to assess the effects of a dietary supplement containing soy isoflavones and alpha-galactooligosaccharides on muscular glucose, glycogen synthase (GSase)and glycogen content in a type 1 diabetic animal model. The dietary supplement tested was a patented compound, Fermented Soy Permeate (FSP), developed by the French Company Sojasun Technologies. Forty male Wistar rats were randomly assigned to control or diabetic groups (streptozotocin, 45?mg/kg). Each group was then divided into placebo or FSP-supplemented groups. Both groups received by oral gavage, respectively, water or diluted FSP (0.1?g/day), daily for a period of 3 weeks. At the end of the protocol, glycemia was noticed after a 24-h fasting period. Glucose, total GSaseand the glycogen content were determined in the skeletal muscle (gastrocnemius). Diabetic animals showed a higher blood glucose concentration, but a lower glucose and glycogen muscle content than controls. Three weeks of FSP consumption allowed to restore the muscle glucose concentration, but failed to reduce glycemia and to normalize the glycogen content in diabetic rats. Furthermore, the glycogen content was increased in FSP-supplemented controls compared to placebo controls. Our results demonstrated that diabetic rats exhibited a depleted muscle glycogen content (-25%). FSP-supplementation normalized the muscle glucose level without restoring the glycogen content in diabetic rats. However, it succeeded to increase it in the control group (+20%).

Resume Introduction . – Cette etude compare l'apport quotidien en vitamines antioxydantes (vitamine E, C, β-carotene) de 28 etudiants en education physique, aux apports nutritionnels conseilles. Un autoquestionnaire alimentaire a permis d'evaluer l'apport calorique journalier, la repartition en macronutriments (G, P, L) et l'apport en vitamines antioxydantes. Synthese des faits . – L'apport calorique quotidien (40,7 ± 1,4 kcal j –1 ) et la repartition en macronutriments (G : 52,2 %, P : 16,9 %, L : 27,2 %) se situe dans les normes pour sportifs moderes. La consommation en vitamines E et C est insuffisante puisque 100 % et 73 % des sportifs, ne couvrent pas leurs apports respectifs. Seuls les apports en β-carotene sont respectes par 78,6 % des sportifs. Conclusions . – Les sportifs etudies presentent une alimentation equilibree en macronutriments, mais souffrent d'un fort deficit en vitamines antioxydantes.

Resume Introduction. – Une etude recente (Groussard et al., communication personnelle) a montre qu'un exercice de sprint isole (30 s) s'accompagne d'une surproduction de radicaux lipidiques et d'une alteration du systeme enzymatique antioxydant sanguin. Ce meme exercice pourrait egalement affecter le statut antioxydant non-enzymatique plasmatique. Synthese des faits. – Huit etudiants en APS, ont realise une epreuve de Wingate. Le statut antioxydant non-enzymatique plasmatique (acide urique, vitamines C et E, β-carotene) a ete evalue au repos (R), a l'arret de l'echauffement (E) a l'arret du test (P0), puis a 5 (P5), 10 (P10), 20 (P20) et 40 (P40) minutes de recuperation. L'exercice de Wingate s'accompagne d'une augmentation de l'acide urique et de la vitamine C respectivement a partir de P10 et P20. A l'inverse, la concentration en vitamine E diminue a P5–P10 puis remonte aux valeurs basales, tandis que le β-carotene chute des P5. Conclusion. – Les resultats demontrent qu'un exercice de sprint isole de 30 s altere egalement le statut antioxydant plasmatique non-enzymatique.

Resume Introduction – Dans cette etude nous avons compare les reponses en catecholamines a l'issue d'une epreuve de Wingate chez des endurants masculins de specialites differentes : 6 specialistes de demi-fond court (DFC) (800 m et 1500 m) et 6 specialistes de demi-fond long (DFL) (5000 m et 10 000 m). Synthese des faits – Les valeurs de consommation maximale d'oxygene sont significativement superieures chez DFL par rapport a DFC (72 ± 2,5 vs 79 ± 4,5 ml min–1 kg–1 de masse maigre respectivement pour DFC et DFL), les performances mesurees lors de l'epreuve de Wingate sont significativement superieures chez DFC (15,8 ± 0,3 vs 14,7 ± 0,4 W kg–1 de masse maigre respectivement pour DFC et DFL). En revanche, la lactatemie maximale et les concentrations maximales d'adrenaline et de noradrenaline ne different pas significativement entre les 2 groupes de sujets (Adrenaline : 3,8 ± 0,7 vs 3,5 ± 0,3 nmol l–1. Noradrenaline : 20,4 ± 1,5 vs 16 ± 2,1 nmol l–1 respectivement pour DFC et DFL). Conclusion – De tels resultats suggerent que la specialite d'endurance est sans effet sur les reponses en catecholamines a l'exercice de sprint.

Low mitochondriogenesis is critical to explain loss of muscle function in aging and in the development of frailty. The aim of this work was to explain the mechanism by which mitochondriogenesis is decreased in aging and to determine to which extent it may be prevented by exercise training. We used aged rats and compared them with peroxisome proliferator-activated receptor-γ coactivator-1α deleted mice (PGC-1α KO). PGC-1α KO mice showed a significant decrease in the mitochondriogenic pathway in muscle. In aged rats, we found a loss of exercise-induced expression of PGC-1α, nuclear respiratory factor-1 (NRF-1), and of cytochrome C. Thus muscle mitochondriogenesis, which is activated by exercise training in young animals, is not in aged or PGC-1α KO ones. Other stimuli to increase PGC-1α synthesis apart from exercise training, namely cold induction or thyroid hormone treatment, were effective in young rats but not in aged ones. To sum up, the low mitochondrial biogenesis associated with aging may be due to the lack of response of PGC-1α to different stimuli. Aged rats behave as PGC-1α KO mice. Results reported here highlight the role of PGC-1α in the loss of mitochondriogenesis associated with aging and point to this important transcriptional coactivator as a target for pharmacological interventions to prevent age-associated sarcopenia., This work was supported by grants SAF2008-00270, SAF2009-08334, and BFU2007-65803/BFI from the Spanish Ministry of Education and Science; PROMETEO/2010/074 from the Consellería de Educación de la Generalitat Valenciana. ISCIII2006-RED13-027 from the “Red Temática de Investigación Cooperativa en Envejecimiento y Fragilidad (RETICEF)”, EU Funded COSTB35 and DPS2008-06968 from Spanish Ministry of Innovation and Science. This study has been cofinanced by FEDER funds from the European Union.

This study investigated the effects of 8 weeks of intense exercise training combined with insulin treatment on the Ca2+-cycling protein complex expression and their functional consequences on cardiac function in type 1 diabetic rat hearts. Diabetic Wistar rats were randomly assigned into the following groups: received no treatment, insulin-treated diabetic, trained diabetic, and trained insulin-treated diabetic. A control group was also included. Insulin treatment and (or) treadmill intense exercise training were conducted over 8 weeks. Basal cardiac function was evaluated by Langendorff technique. Cardiac expression of the main Ca2+-cycling proteins (RyR2, FKBP 12.6, SERCA2, PLB, NCX1) was assessed by Western blot. Diabetes altered basal cardiac function (±dP/dt) and decrease the expression of the main Ca2+-cycling proteins expression: RyR2, SERCA2, and NCX1 (p < 0.05). Whereas combined treatment was not able to normalize –dP/dt, it succeeded to normalize +dP/dt of diabetic rats (p < 0.05). Moreover, both insulin and intense exercise training, applied solely, increased the expression of the Ca2+-cycling proteins: RyR2, SERCA2, PLB. and NCX1 (p < 0.05). But this effect was higher when the 2 treatments were combined. These data are the first to show that combined insulin treatment and intense exercise training during diabetes synergistically act on the expression of the main Ca2+-cycling proteins, providing insights into mechanisms by which the dual treatment during diabetes improves cardiac function.

International audience; This study examined the effects of a dual treatment combining insulin treatment and exercise training on basal cardiac function and signaling pathways involving β3-AR, NOS1, and RyR2 in type 1 diabetic rats. Male Wistar rats were assigned into a diabetic group receiving no treatment (D), an insulin-treated diabetic (Ins), a trained diabetic (TD), and a trained insulin-treated diabetic (TIns) group. Control group (C) was included in order to confirm the deleterious effects of diabetes. Insulin treatment and/or treadmill exercise training were conducted for 8 weeks. Basal cardiac function was evaluated by Langendorff technique. Cardiac protein expression of β3-AR, NOS1, and RyR2 was assessed using Western blots. Diabetes induced a decrease of both basal diastolic and systolic (±dP/dt) cardiac function (P < 0.05). Moreover, diabetes was associated with an increase of β3-AR and NOS1 and a decrease of RyR2 expression (P < 0.05). Although combined treatment was not able to normalize -dP/dt, it succeeded to normalize +dP/dt of diabetic rats. Combined treatment led to an overexpression of RyR2. Effects of this combined treatment on +dP/dt and RyR2 were greater than the effects of insulin and exercise training, applied solely. Treatments, applied solely or in combination, resulted in a complete normalization of β3-AR and in a down-regulation of NOS1 because this protein expression in all treated diabetic rats became lower than control values (P < 0.01). Our study shows that unlike single treatments, dual treatment combining insulin treatment and exercise training was able to normalize basal systolic function of diabetic rats by a specific regulation of β3-AR-NOS1-RyR2 signaling pathways.

The purpose of this study was to determine the relationship between athletic performance and the change in body weight (BW) during a 42 km marathon in a large cohort of runners.The study took place during the 2009 Mont Saint-Michel Marathon (France). 643 marathon finishers (560 males and 83 females) were studied. The change in BW during the race was calculated from measurements of each runner's BW immediately before and after the race.BW loss was 2.3 ± 2.2% (mean±SEM) (p0.01). BW loss was -3.1 ± 1.9% for runners finishing the marathon in less than 3 h; -2.5 ± 2.1% for runners finishing between 3 and 4 h; and -1.8 ± 2.4% for runners who required more than 4 h to complete the marathon. The degree of BW loss was linearly related to 42 km race finishing time (p0.0000001). Neither age nor gender influenced BW loss during the race.BW loss during the marathon was inversely related to race finishing time in 643 marathon runners and was3% in runners completing the race in less than 3 h. These data are not compatible with laboratory-derived data suggesting that BW loss greater than 2% during exercise impairs athletic performance. They match an extensive body of evidence showing that the most successful athletes in marathon and ultra-marathon running and triathlon events are frequently those who lose substantially more than 3-4% BW during competition.

The aim of this paper is to validate a new method of energy expenditure (EE) estimation stemming solely from the measurement of rib cage, abdominal and chest wall distances. We set out to prove that the variations of these distances, measured by two pairs of electromagnetic coils, lead to the estimation of the ventilation (VE) and the EE. Eleven subjects were recruited to take part in this study (27.6 ± 5.4 years; 73.7 ± 9.7 kg). Each subject participated in two tests. The objective of Test 1 was to determine the individual and group equations between the VE and EE during light to moderate activities while Test 2 compared the two pairs of electromagnetic coils with the indirect calorimetry so as to estimate EE in upright sitting and standing positions and during walking exercises. During Test 2, we compared EE measured by indirect calorimetry (EE(IC-Val-REF)) with EE estimated by the two pairs of electromagnetic coils through the application of: (1) the individual equation (EE(mag-Val-INDIV)) and (2) the group equation (EE(mag-val-GROUP)). The results show that there is no significant difference between EE(IC-Val-REF) and EE(mag-Val-INDIV) and between EE(IC-Val-REF) and EE(mag-val-GROUP) for each activity. Furthermore, the mean difference seems to show that the estimation of EE is better with the group equation. In conclusion, on the proven basis of this study we are able to validate this new method which permits the estimation of EE from abdominal and rib cage distances. This study also highlights the advantage of using a group equation to the estimate EE.

Background Informations about the effects of intense exercise training on diabetes-induced myocardial dysfunctions are lacking. We have examined the effects of intense exercise training on the cardiac function of diabetic rats, especially focusing on the Langendorff β-adrenergic responsiveness and on the β-adrenoceptors protein expression. Methods Control or Streptozotocin induced-diabetic male Wistar rats were randomly assigned to sedentary or trained groups. The training program consisted of 8 weeks running on a treadmill (10° incline, up to 25 m/min, 60 min/day) and was considered to be intense for diabetic rats. Results This intense exercise training amplified the in vivo diabetes-induced bradycardia. It had no effect on Langendorff basal cardiac contraction and relaxation performances in control and diabetic rats. In diabetic rats, it accentuated the Langendorff reduced responsiveness to β-adrenergic stimulation. It did not blunt the diabetes-induced decrease of β1-adrenoceptors protein expression, displayed a significant decrease in the β2-adrenoceptors protein expression and normalized the β3-adrenoceptors protein expression. Conclusions Intense exercise training accentuated the decrease in the myocardial responsiveness to β-adrenergic stimulation induced by diabetes. This defect stems principally from the β2-adrenoceptors protein expression reduction. Thus, these results demonstrate that intense exercise training induces specific effects on the β-adrenergic system in diabetes.

To validate a new device designed to measure ventilation \( \left( {\dot{V}_{\text{E}} } \right), \) tidal volume (VT), inspiratory time (TI), and expiratory time (TE) during daily life activities. The anteroposterior displacement of the rib cage and abdomen and the axial displacements of the chest wall and the spine were measured using two pairs of magnetometers. \( \dot{V}_{\text{E}} \) was estimated from these four signals, and was simultaneously measured using a spirometer. A total of 707, 732, and 1,138 breaths were analyzed in sitting, standing, and exercise conditions, respectively. We compared \( \dot{V}_{\text{E}} \), VT, TI, and, TE measured by magnetometers (\( \dot{V}_{{{\text{E}}\;{\text{mag}}}} \), VT mag, TI mag, and TE mag) with \( \dot{V}_{\text{E}} \), VT, TI, and TE measured by a spirometer (\( \dot{V}_{{{\text{E}}\;{\text{spiro}}}} \), VT spiro, TI spiro, and TE spiro, respectively). For pooled data \( \dot{V}_{{{\text{E}}\;{\text{mag}}}} \), VT mag, TI mag, and TE mag were significantly correlated (p < 0.001) with \( \dot{V}_{{{\text{E}}\;{\text{spiro}}}} \), VT spiro, TI spiro, and TE spiro in sitting and standing positions and during the walking exercise. The mean differences, between \( \dot{V}_{{{\text{E}}\;{\text{mag}}}} \), and \( \dot{V}_{{{\text{E}}\;{\text{spiro}}}} \) for the group, were 10.44, 10.74, and 12.06% in sitting, standing, and exercise conditions, respectively. These results demonstrate the capacity of this new device to measure \( \dot{V}_{\text{E}} \) with reasonable accuracy in sitting, standing, and exercise conditions.

The aim of this study is to compare the relation between ventilation (VE) and oxygen uptake (VO2) [VO2=ƒ(VE)] and between heart rate (HR) and VO2 [VO2=ƒ(HR)]. Each one of the subjects performed three types of activities of different intensities (walking without load, walking with load and intermittent work). VO2, VE, and HR were measured continuously by using indirect calorimetry and an electrocardiogram. Linear regressions and coefficients of determination (r(2)) were calculated to compare the relation VO2 =ƒ(VE) and VO2 =ƒ(HR) for two different regroupings: by session duration (r(2) session) and by subject (r(2) subject). Results showed that r(2) session of the relation VO2 =ƒ(VE) were significantly higher than those of the relation VO2 =ƒ(HR) for steady state activities (walking with or without load during 3 or 6 min, p0.01) and for activities without oxygen consumption steady state (walking with or without load during 1 min, p0.01 and intermittent work, p0.05). VE is more strongly correlated with VO2 than with HR. This is a very promising approach to develop a new method to estimate energy expenditure. Key pointsVentilation is more strongly correlated with oxygen uptake than heart rate during physical activities of different intensities.This study shows the interest to looking for ventilation to estimate energy expenditure.This study is a promising approach to develop a new method to estimate energy expenditureAn interesting perspective could be to develop a light and portable device to measure ventilation based on the coupling of four magnetometers.

Ten prepubertal boys performed 60-min cycle exercise at about 60% of their maximal oxygen uptake as previously measured. To measure packed cell volume, plasma glucose, free fatty acids (FFA), glycerol and catecholamines, blood samples were drawn at rest using a heparinized cathether and at the 15th, 30th and 60th min of the exercise and after 30 min of recovery. At rest, the blood glucose concentrations were at the lowest values for normal. Exercise induced a small decrease of blood glucose which was combined with an abrupt increase of the noradrenaline concentration during the first 15 min. The FFA and glycerol concentrations increased throughout the exercise linearly with that of adrenaline. Compared to adults, the FFA uptake expressed per minute and per litre of oxygen uptake was greater in children. These results suggested that it is difficult for children to maintain a constant blood glucose concentration and that prolonged exercise provided a real stimulus to hypoglycaemia. An immediate and large increase in noradrenaline concentration during exercise and a greater utilization of FFA was probably used by children to prevent hypoglycaemia.

The purpose of this study is to examine the effects of the “Marathon of Sands” (MS), a 7-day, self-sufficient-diet, multi-stage running race across a section of the Moroccan desert, on body weight and plasma volume variation (PVV) and the relationship of these factors to performance in athletes who are well-trained in endurance. Sixteen MS runners agreed to participate in this study. Weight and body composition were measured and venous blood samples were taken before the first stage (D 0 ), after the third stage (D 3 ) and at the end of the MS (after the sixth stage: D 6 ). Haematocrit and haemoglobin were used to calculate PVV at (D 0 , D 3 , and D6). No significant plasma volume decrease was observed throughout the race. Significant decreases in total body weight (BW), fat-free mass (FFM) and fat mass (FM) were observed in D 3 and D 6 (−4.3%, −3.5%, −0.8%; and −6.1%, −5%, −1.1%, respectively, for BW, FFM and FM at D 3 and D 6 ). This study clearly shows that, despite extreme conditions, the MS did not lead to a significant PV decrease in athletes well-trained in endurance. This study also supports the hypothesis that significant body weight loss may not systematically affect performances during long duration multiple-stage races.

Several methods have tried to quantify physical activity using the relation between heart rate (HR) and oxygen consumption (\( \dot V \)O2). Considering the limits of this relation, we focus our work on another physiological index: ventilation (\( \dot V \) E). The aim of this study is to show that \( \dot V \) E is more strongly correlated with \( \dot V \)O2 than HR. Eight male subjects carried out four physical activities of various intensities: walking at 4 km.h−1, walking at 4 km.h−1 with load, running at 8 km.h−1 and cycling at 60 W. The ventilatory parameters (\( \dot V \)O2 and \( \dot V \) E) were measured by a portable indirect calorimetry system (VO2000 MedGraphics) and HR was measured with a cardiofrequencemeter. Coefficients of determination (r2 linear) of the relations \( \dot V \)O2=f(\( \dot V \) E) and \( \dot V \)O2=f(HR) were calculated for each subject (on each activity [r2 Ttot: 64 regressions], on all the four activities [r2 4activities: 16 regressions]) and then for the eight subjects joined together on all the four activities (r2 global: 2 regressions). Results showed that the r2 Ttot of the relation \( \dot V \)O2=f(\( \dot V \) E) were significantly higher than those of the relation \( \dot V \)O2=f(HR) for the tasks: walking at 4 km.h−1 (p

Basal insulin resistance (IR) and inflammation exacerbate post-exercise oxidative stress (OS) in overweight adolescent girls.Cross-sectional study, effect of incremental ergocycle exercise until exhaustion on OS markers.Normal-weight (control) (n=17, body mass index (BMI): 20-24.2 kg/m(2)) and overweight adolescent girls (n=29, BMI: 24.1-36.6 kg/m(2)).Dietary measurement, physical activity assessment (validated questionnaires), fat distribution parameters (by dual-energy X-ray absorptiometry and anthropometry) and maximal oxygen consumption (VO2peak). Blood assays include the following: (1) at fasting state: blood cell count, lipid profile, and IR parameters (leptin/adiponectin ratio (L/A), homeostasis model assessment of IR, insulin/glucose ratio; (2) before exercise: inflammation and OS markers (interleukin-6 (IL-6), C-reactive protein (CRP), myeloperoxidase (MPO), reduced glutathione/oxidized glutathione ratio (GSH/GSSG), 15 F(2)alpha-isoprostanes (F(2)-Isop), lipid hydroperoxides (ROOH), oxidized low-density lipoprotein (ox-LDL)) and antioxidant status (superoxide dismutase (SOD), glutathione peroxidase (GPX), vitamin C, alpha-tocopherol and beta-carotene); and (3) after exercise: inflammation and OS markers.At rest, overweight girls had a deteriorated lipid profile and significantly higher values of IR parameters and inflammation markers, compared with the control girls. These alterations were associated with a moderate rest OS state (lower GSH/GSSG ratio, alpha-tocopherol/total cholesterol (TC) ratio and GPX activity). In absolute values, overweight girls exhibited higher peak power output and oxygen consumption (VO2peak), compared with the control girls. Exercise exacerbated OS only in the overweight group (significant increase in F(2)-Isop, ROOH and MPO). As hypothesized, basal IR and inflammation state were correlated with the post-exercise OS. However, the adjustment of F(2)-Isop, ROOH and MPO variation per exercise VO(2) variation canceled the intergroup differences.In overweight adolescent girls, the main factors of OS, after incremental exhaustive exercise, are not the basal IR and inflammation states, but oxygen overconsumption.