Neuregulin 1 affects leptin levels, food intake and weight gain in normal-weight, but not obese, db/db mice

Aim. - Studies in vitro have highlighted the potential involvement of neuregulin 1 (NRG1) in the regulation of energy metabolism. This effect has also been suggested in vivo, as intracerebroventricular injection of NRG1 reduces food intakes and weight gain in rodents. Thus, it was hypothesised that NRG1 might affect serum leptin levels in mice. Methods. - Weight, food intakes, energy expenditure, spontaneous physical activity and serum leptin levels were evaluated in normal-weight C57BL/6JRJ mice following intraperitoneal administration of NRG1 (50 mu g/kg, three times/week) or saline for 8 weeks. Based on the results of this first experiment, leptin-resistant obese db/db mice were then given NRG1 for 8 weeks. Results. - Leptin serum concentrations were six times higher in C57BL/6JRJ mice treated with NRG1 than in the animals given saline. NRG1 treatment also reduced weight gain by 10% and food intakes by 15% compared with saline treatment, while energy expenditure remained unchanged. In db/db mice, serum leptin concentrations, weight gain, food intakes, energy expenditure and spontaneous physical activity were not altered by NRG1 treatment. Conclusion. - The decrease in food intakes and weight gain associated with NRG1 treatment in C57BL/6JRJ mice may be partly explained by increased leptin levels, whereas db/db mice were not affected by the treatment, suggesting resistance to NRG1 in this pathological state

Knee extension strength in obese and nonobese male adolescents

The aim of the present study was to compare “absolute” and “relative” knee extension strength between obese and nonobese adolescents. Ten nonobese and 12 severely obese adolescent boys of similar chronological age, maturity status, and height were compared. Total body and regional soft tissue composition were determined using dual-energy X-ray absorptiometry (DXA). Knee extensors maximum voluntary contraction (MVC) torque was measured using an isometric dynamometer at a knee angle of 60° (0° is full extension). Absolute MVC torque was significantly higher in obese adolescents than in controls. However, although MVC torque expressed per unit of body mass was found to be significantly lower in obese adolescent boys, no significant difference in MVC torque was found between groups when normalized to fat-free mass. Conversely, when correcting for thigh lean mass and estimated thigh muscle mass, MVC torque was significantly higher in the obese group (17.9% and 22.2%, respectively; P <0.05). To conclude, our sample of obese adolescent boys had higher absolute and relative knee extension strength than our nonobese controls. However, further studies are required to ascertain whether or not relative strength, measured with more accurate in vivo methods such as magnetic resonance imaging, is higher in obese adolescents than in nonobese controls

Large‐scale modelling of deep‐diving cetacean habitats

Versión del editor5,14

Recommandations pour la pratique clinique : « Interventions pendant la période périnatale ». Chapitre 1 Partie 1 : Activité Physique et santé maternelle

L’objectif de ce travail était de faire un état des lieux des effets bénéfiques d’une activité physique (AP) régulière et/ou d’une moindre sédentarité avant, pendant et après la grossesse, en s’appuyant sur des publications scientifiques, des méta-analyses et certains rapports de sociétés savantes. En période pré-conceptionnelle, il est recommandé de proposer 30 min à 1h d’AP d’intensité modérée à élevée par jour ou tout au moins 5 jours par semaine, en évitant de rester 2 jours consécutifs sans pratiquer. Il est recommandé aux femmes enceintes de i) commencer ou de maintenir une AP d’intensité modérée ≥ à 150 min par semaine avec au moins trois sessions d’une durée supérieure à 30 min, ii) de commencer ou maintenir des exercices de renforcement musculaire impliquant de grands groupes musculaires (1 à 2 fois par semaine). En l’absence de contre-indication médicale, il est recommandé de poursuivre une AP (au moins 30 min par jour) en post-partum. Le temps de sédentarité est à limiter au maximum, si possible ≤ à 7h par jour quelle que soit la période

Topic 1. Reducing fat mass and weight: strategies and potential risks for high-level athletes

The strategies used by athletes to reduce body weight and control fat mass aim to favour performance while increasing the ratio between lean and fat mass.In high-level athletes, as daily energy expenditure is high, the best strategy when seeking to lose weight and reduce fat mass is to decrease the total energy intake. Some strategies aiming to limit appetite can also be suggested. From a practical point of view, various approaches are possible, including modulation of meal frequency, high-protein diets, increasing glycogen storage, high-intensity intermittent exercises, etc.Body weight changes must be progressive, implemented exclusively during training periods, and should not involve significant energy restriction or high-risk behaviour. On average, the weight-loss aimed for should be around 0.5 to 0.9 kg/week, but should never exceed 1.5 kg of body weight per week. Indeed, most of the time significant weight reduction reflects dehydration, nutritional deficiencies and sometimes proteolysis; all of which have negative effects on physiology, nutritional status and performance.Psychological pressures exerted by the athletes’ entourage can induce significant behavioural disorders, including eating disorders. Educational programmes for coaches and athletes could help to limit some dangerous practices which are still observed (mainly in “aesthetic” sports or in weight-category sports)

Physical Activity During the Perinatal Period: Guidelines for Interventions During the Perinatal Period from the French National College of Midwives

International audienc

Substrate metabolism during exercise: sexual dimorphism and women’s specificities

International audienceThe aim of this review is to discuss sexual dimorphism of energy metabolism, and to describe the impact of women's hormonal status on substrate oxidation during exercise. Many evidences indicate that sex steroids play a pivotal role in the sex-related differences of body composition and energy substrate storage. Compared with men, women rely more on fat and less on carbohydrates at the same relative exercise intensity. Scientific data suggest that 17-beta oestradiol is a key hormone for the regulation of body composition and substrate metabolism. However, in women, measurements with stable isotopic tracers did not highlight any difference in whole-body substrate oxidation rates between the follicular and luteal phases of the menstrual cycle during endurance exercise. The remaining discrepancies about the effect of menstrual cycle-related hormone fluctuations on substrate oxidation could be partly explained by the exercise intensity, which is an important regulator of substrate oxidation. Due to their specific nature and concentration, the synthetic ovarian hormones contained in oral contraceptives also influence substrate metabolism during endurance exercise. However, more studies are needed to confirm that oral contraceptives increase lipolytic activity during endurance exercise without any substantial (or detectable) effect on substrate utilization. Pregnancy and menopause also modify body composition and substrate utilization during exercise through specific hormonal fluctuations. This review highlights that the hormonal status is likely to affect substrate oxidation during exercise in women emphasizing the need to take it into consideration to optimize their health and performance

Obésité et activité physique. Symposium.

National audienceno abstrac