Purpose: To investigate the effects of a 3-week weight-management program entailing moderate energy restriction, nutritional education, psychological counseling and three different exercise training (a: low intensity, LI: 40 % Vâ\u80²O2max; b: high intensity, HI: 70 % Vâ\u80²O2max; c: high-intensity interval training, HIIT), on body composition, energy expenditure and fat oxidation rate in obese adolescents. Methods: Thirty obese adolescents (age: 15â\u80\u9317 years, BMI: 37.5 kg mâ\u88\u922) participated in this study. Before starting (week 0, W0) and at the end of the weight-management program (week 3, W3), body composition was assessed by an impedancemeter; basal metabolic rate (BMR), energy expenditure and substrate oxidation rate were measured during exercise and post-exercise recovery by indirect calorimetry. Results: At W3, body mass (BM) and fat mass (FM) decreased significantly in all groups, the decreases being significantly greater in the LI than in the HI and HIIT subgroups (BM: â\u88\u928.4 ± 1.5 vs â\u88\u926.3 ± 1.9 vs â\u88\u924.9 ± 1.3 kg and FM: â\u88\u924.2 ± 1.9 vs â\u88\u922.8 ± 1.2 vs â\u88\u922.3 ± 1.4 kg, p < 0.05, respectively). Vâ\u80²O2peak, expressed in relative values, changed significantly only in the HI and HIIT groups by 0.009 ± 0.005 and 0.007 ± 0.004 L kg FFMâ\u88\u921 minâ\u88\u921 (p < 0.05). Furthermore, the HI and HIIT subgroups exhibited a greater absolute rate of fat oxidation between 50 and 70 % Vâ\u80²O2peak at W3. No significant changes were observed at W3 in BMR, energy expenditure during exercise and post-exercise recovery. Conclusion: A 3-week weight-management program induced a greater decrease in BM and FM in the LI than in the HI and HIIT subgroups, and greater increase in Vâ\u80²O2peak and fat oxidation rate in the HI and HIIT than in the LI subgrou

Background. Exercise is recognized to evoke multisystemic adaptations that, particularly in obese subjects, reduce body weight, improve gluco-metabolic control, counteract sarcopenia and lower the risk of cardiometabolic diseases. Understanding the molecular and cellular mechanisms of exercise-induced benefits is of great interest due to the therapeutic implications against obesity.Objectives and methods. The aim of the present study was to evaluate time-related changes in size distribution and cell origin of extracellular vesicles (EVs) in obese and normal-weight subjects who underwent a moderate-intensity exercise on a treadmill (at 60% of their VO2max). Blood samples were drawn before, immediately at the end of the exercise and during the post-exercise recovery period (3h and 24h). Circulating EVs were analyzed by a nanoparticle tracking analysis and flow cytometry after labeling with the following cellspecific markers: CD14 (monocyte/macrophage), CD61 (platelet), CD62E (activated endothelium), CD105 (total endothelium), SCGA (skeletal muscle) and FABP (adipose tissue).Results. In all subjects, acute exercise reduced the release of total (i.e., 30-700 nm) EVs in circulation, predominantly EVs in the microvesicle size range (i.e., 130-700 nm EVs). The post-exercise release of microvesicles was higher in normal-weight than obese subjects; after exercise, circulating levels of exosomes (i.e., 30-130 nm EVs) and microvesicles were, respectively, lower and higher in females than males. In all experimental subgroups (males vs. females and obese vs. normal-weight subjects), acute exercise reduced and increased, respectively, CD61+ and SCGA+ EVs, being the effect on CD61+ EVs prolonged up to 24h after the end of the test with subjects in resting conditions. Total EVs, exosomes and CD61+ EVs were associated with HOMA-IR.Conclusions. Though preliminary, the results of the present study show that a single bout of acute exercise modulates the release of EVs in circulation, which are tissue-, sex-and BMI specific, suggesting that the exercise-related benefits might depend upon a complex interaction of tissue, endocrine, and metabolic factors.

In obesity, the increased O cost of breathing negatively affects the O cost of exercise and exercise tolerance. The purpose of the study was to determine whether, in obese adolescents, the addition of respiratory muscle endurance training (RMET) (isocapnic hyperpnea) to a standard body mass reduction program decreases the O cost of exercise and perceived exertion. Nine male obese adolescents [16.0 ± 1.4 yr ( ± SD), body mass 114.4 ± 22.3 kg] underwent 3 wk of RMET (5 days/week) in addition to a standard body mass reduction program. Eight age- and sex-matched obese adolescents underwent only the standard program (CTRL). Before and after interventions, patients performed on a cycle ergometer: incremental exercise; 12-min exercises at a constant work rate (CWR) of 65% and 120% at the gas exchange threshold (GET) determined before the intervention. Breath-by-breath pulmonary ventilation (V̇e) and O uptake (V̇o), heart rate (HR), and ratings of perceived exertion for dyspnea/respiratory discomfort (RPE) and leg effort (RPE) were determined. Body mass decreased (by ~3.0 kg) after both RMET ( = 0.003) and CTRL ( = 0.002). Peak V̇o was not affected by both interventions. Peak work rate was slightly, but significantly ( = 0.04), greater after RMET but not after CTRL. During CWR < GET, no changes were observed after both interventions. During CWR > GET, the O cost of cycling at the end of exercise ( = 0.02), the slope of V̇o vs. time (3-12 min) ( = 0.01), RPE ( = 0.01), and RPE ( = 0.01) decreased following RMET, but not following CTRL. HR decreased after both RMET ( = 0.02) and CTRL ( = 0.03), whereas V̇e did not change. In obese adolescents RMET, superimposed on a standard body mass reduction program, lowered the O cost of cycling and perceived exertion during constant heavy-intensity exercise.

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Metabolic syndrome is a combination of cardiometabolic risk factors, frequently detected in obese children and adolescents. To date, few clinical studies have evaluated the effectiveness of multidisciplinary body weight reduction programs on body mass index, body composition, muscle performance and fatigue in pediatric obese subjects suffering from metabolic syndrome, which might represent a sub-population that is more difficult to be treated and worthy of more intensive interventions than a population less metabolically complicated. The aim of the present study was to compare the impact of a three-week in-hospital multidisciplinary integrated body weight reduction program (BWRP) on body mass index (BMI), body composition (particularly, fat mass (FM) and fat-free mass (FFM)), motor control (evaluated by one-leg standing balance (OLSB) test), muscle performance (evaluated by the stair climbing test (SCT)) and fatigue (evaluated by fatigue severity scale (FSS)) in a pediatric obese population with or without metabolic syndrome. A pediatric population of 548 obese subjects without metabolic syndrome (F/M = 312/236; age range: 8–18 years; BMI: 36.3 ± 6.7 kg/m2) and 96 obese subjects with metabolic syndrome (F/M = 53/43; age range: 9–18 years; BMI: 38.3 ± 6.9 kg/m2) was recruited. The BWRP significantly reduced BMI, FM (expressed as %), SCT time and FSS score, and increased OLSB time in all subgroups of obese subjects, independent of sex and metabolic syndrome, with preservation of FFM. No significant differences in |ΔBMI|, |ΔFM|, |ΔOLSB| or |ΔSCT| times and |ΔFSS| score were found when comparing subjects (males and females) with or without metabolic syndrome, apart from obese females without metabolic syndrome, who exhibited a lower weight loss and FM (expressed as %) reduction when compared to the corresponding male counterpart. In conclusion, the beneficial effects of a three-week BWRP on BMI, body composition, muscle performance and fatigue in a pediatric obese population were not found to be different in patients with or without metabolic syndrome, thus indicating that the more metabolically compromised patient is as responsive to a short-term BWRP as the patient without metabolic syndrome. More prolonged follow-up studies are, however, necessary in order to verify whether the adherence to the multidisciplinary recommendations at home and the long-term maintenance of the positive effects in the two subgroups of patients will remain similar or not.

Abstract:The objective of this study was to characterize static and dynamic thoraco-abdominal volumes in obese adolescents and to test the effects of a 3-week multidisciplinary body weight reduction program (MBWRP), entailing an energy-restricted diet, psychological and nutritional counseling, aerobic physical activity, and respiratory muscle endurance training (RMET), on these parameters. Total chest wall (V CW ), pulmonary rib cage (V RC,p ), abdominal rib cage (V RC,a ), and abdominal (V AB ) volumes were measured on 11 male adolescents (Tanner stage: 3-5; BMI standard deviation score: >2; age: 15.9 ± 1.3 years; percent body fat: 38.4%) during rest, inspiratory capacity (IC) maneuver, and incremental exercise on a cycle ergometer at baseline and after 3 weeks of MBWRP. At baseline, the progressive increase in tidal volume was achieved by an increase in end-inspiratory V CW (p < 0.05) due to increases in V RC,p and V RC,a with constant V AB . End-expiratory V CW decreased with late increasing V RC,p , dynamically hyperinflating V RC,a (p < 0.05), and progressively decreasing V AB (p < 0.05). After MBWRP, weight loss was concentrated in the abdomen and total IC decreased. During exercise, abdominal rib cage hyperinflation was delayed and associated with 15% increased performance and reduced dyspnea at high workloads (p < 0.05) without ventilatory and metabolic changes. We conclude that otherwise healthy obese adolescents adopt a thoracoabdominal operational pattern characterized by abdominal rib cage hyperinflation as a form of lung recruitment during incremental cycle exercise. Additionally, a short period of MBWRP including RMET is associated with improved exercise performance, lung and chest wall volume recruitment, unloading of respiratory muscles, and reduced dyspnea.Key words: obesity, pediatrics, exercise, pulmonary physiology, exercise physiology, kinesiology.Résumé : Cette étude a pour objectif de déterminer les volumes thoraco-abdominaux statiques et dynamiques chez des adolescents obèses et d'évaluer sur ces variables les effets de 3 semaines d'un programme multidisciplinaire de perte de poids (MBWRP) comprenant un régime restrictif, du counseling psychologique et nutritionnel, de l'activité physique aérobie et un entraînement en endurance des muscles respiratoires (RMET). On mesure les volumes de la cage thoracique totale (V CW ), du compartiment pulmonaire (V RC,p ), du compartiment abdominal (V RC,a ) et de l'abdomen (V AB ) de 11 adolescents mâles (stade de Tanner : 3-5, IMC > 2 écarts-types, âge 15,9 ± 1,3 ans, pourcentage de gras corporel : 38,4 %) au repos, la capacité inspiratoire (IC), une manoeuvre de capacité inspiratoire (IC) et un test d'effort progressif sur cycloergomètre au début et après 3 semaines de MBWRP. Au début, le volume courant s'accroit progressivement par l'augmentation de V CW à la fin de l'inspiration (p < 0,05) due à l'agrandissement des deux compartiments de la cage thoracique, V AB demeurant constant. V CW à la fin de l'expiration diminue en présence d'une augmentation...

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Purpose“Slow components” of heart rate (HR) kinetics, occurring also during moderate-intensity constant work rate exercise, represent a problem for exercise prescription at fixed HR values. This problem, described in young healthy subjects, could be more pronounced in obese patients.MethodsSixteen male obese patients (age, 22 ± 7 yr; body mass, 127 ± 19 kg; body mass index, 41.6 ± 3.9 kg·m−2) were tested before (PRE) and after (POST) a 3-wk multidisciplinary body mass reduction program, entailing moderate-intensity exercise. They performed on a cycle ergometer an incremental exercise to voluntary exhaustion (to determine peak pulmonary oxygen uptake (V˙O2peak) and gas exchange threshold (GET)) and constant work rate exercises: moderate-intensity (MODERATE; 80% of GET determined in PRE), heavy-intensity (HEAVY; 120% of GET determined in PRE), and “HRCLAMPED” exercise, in which work rate was continuously adjusted to maintain a constant HR corresponding to that at 120% of GET. Breath-by-breath V˙O2 and HR were determined.ResultsV˙O2peak and GET (expressed as a percent of V˙O2peak) were not significantly different in PRE versus POST. In POST versus PRE, the HR slow component disappeared (MODERATE) or was reduced (HEAVY). In PRE, work rate had to decrease by ~20% over a 15-min task in order to keep HR constant; this decrease was significantly smaller (~5%) in POST.ConclusionsIn obese patients, a 3-wk multidisciplinary body mass reduction intervention i) increased exercise tolerance by eliminating (during MODERATE) or by reducing (during HEAVY) the slow component of HR kinetics, and ii) facilitated exercise prescription by allowing to translate a fixed submaximal HR value into a work rate slightly above GET.