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Bedogni G.,Centro Studi Fegato | Gastaldelli A.,CNR Institute of Clinical Physiology | Agosti F.,Laboratorio Sperimentale Ricerche Auxo Endocrinologiche | De Col A.,Laboratorio Sperimentale Ricerche Auxo Endocrinologiche | And 4 more authors.
Journal of Endocrinological Investigation | Year: 2012

Background: Although an association between insulin resistance (IR) and body adiposity has been reported in obese children, this relationship has not been studied as thoroughly as in adults. Aim: We evaluated the association between oral glucose tolerance testing (OGTT) and percent body fat (PBF) in a sample of 1512 obese children followed at a Pediatric Obesity Clinic. Subjects and methods: Six hundred and twenty-eight male and 884 female obese children aged 6 to 18 yr were consecutively enrolled into the study. OGTT was performed with administration of 1.75 g of glucose per kg of body weight (up to 75 g). PBF was estimated through bioelectrical impedance analysis (BIA) using a pop-ulation- specific formula recently published by our group. Multivariable median regression was used to evaluate the association between 4 outcomes [glucose area under the curve (AUC), insulin AUC, insulin sensitivity index (ISI), and insulinogenic index (IGI)] and gender, age or pubertal status and PBF. Results: Median PBF was 52% (range 26 to 70%). After correction for age and gender, a 10% increase of PBF was associated with a decrease of -0.50 [95% confidence interval (CI): -0.65 to -0.35] units of ISI and an increase of 0.15 units of IGI (95%CI 0.07 to 0.24). Conclusions: In obese children, PBF is inversely associated with IR and directly associated to β-cell response as detected by OGTT. ©2012, Editrice Kurtis.

Bedogni G.,University of Trieste | Bedogni G.,University of Milan | Gastaldelli A.,CNR Institute of Clinical Physiology | Manco M.,Direzione Scientifica | And 4 more authors.
Nutrition, Metabolism and Cardiovascular Diseases | Year: 2012

Background and aims: Early onset type 2 diabetes mellitus (T2DM) is associated with obesity, insulin resistance and impaired beta-cell function. Non-alcoholic fatty liver disease (NAFLD) may be an independent risk factor for T2DM. We investigated the relationship between NAFLD and glucose metabolism in a large sample of obese children. Methods and Results: A total of 571 obese children (57% males and 43% females) aged 8-18 years were consecutively studied at a tertiary care centre specialised in paediatric obesity. Liver ultrasonography was used to diagnose NAFLD after exclusion of hepatitis B and C and alcohol consumption. Oral-glucose tolerance testing (OGTT) was performed; insulin sensitivity was evaluated by using the insulin sensitivity index (ISI) and beta-cell function by using the ratio between the incremental areas under the curve (AUC) of insulin and glucose (incAUCins/incAUCglu). A total of 41% of the obese children had NAFLD. Impaired glucose tolerance or T2DM was present in 25% of the children with NAFLD versus 8% of those without it (p< 0.001). Children with NAFLD had higher body mass index (BMI), fasting glucose, 120-min OGTT glucose, incAUCins/incAUCglu and lower ISI as compared with children without NAFLD (p≤ 0.002). At bootstrapped multivariable median regression analysis controlling for gender, age, pubertal status and BMI, NAFLD was an independent predictor of 120-min OGTT glucose and ISI, but not of incAUCins/incAUCglu. Similar findings were obtained using continuous liver steatosis as the predictor, instead of dichotomous NAFLD. Conclusion: NAFLD was present in 41% of our obese children and was associated with higher insulin resistance, but not with impaired beta-cell function. © 2010 Elsevier B.V.

Minetto M.A.,University of Turin | Minetto M.A.,Polytechnic University of Turin | Botter A.,Polytechnic University of Turin | Sprager S.,University of Maribor | And 4 more authors.
Journal of Electromyography and Kinesiology | Year: 2013

The aims of this study were to examine if surface EMG signals can be detected from the quadriceps femoris muscle of severely obese patients and to investigate if differences exist in quadriceps force and myoelectric manifestations of fatigue between obese patients and lean controls.Fourteen severely obese patients (body mass index, BMI, mean±SD: 44.9±6.3kg/m2) and fourteen healthy controls (BMI: 23.7±2.5kg/m2) were studied. The vastus medialis and lateralis of the dominant thigh were concurrently investigated during voluntary isometric contractions (10-s long at submaximal and maximal intensities and intermittent submaximal contractions until exhaustion) and sustained (120-s long) electrically elicited contractions.We found that the detection of surface EMG signals from the quadriceps is feasible also in severely obese subjects presenting increased thickness of the subcutaneous fat tissue. In addition, we confirmed and extended previous findings showing that the volume conductor properties determine the amplitude and spectral features of the detected surface EMG signals: the lower the subcutaneous tissue thickness, the higher the amplitude and mean frequency estimates. Further, we found no differences in the mechanical and myoelectric manifestations of fatigue during intermittent voluntary and sustained electrically elicited contractions between obese patients and lean controls. © 2012 Elsevier Ltd.

Lafortuna C.L.,CNR Institute of Molecular Bioimaging and Physiology | Chiavaroli S.,University of LAquila | Rastelli F.,University of LAquila | De Angelis M.,University of LAquila | And 3 more authors.
Journal of Endocrinological Investigation | Year: 2011

Aims: The purpose of the study was to assess energy expenditure and cardiovascular response to rhythmic activity with 6 machines exercising different arm and leg muscle groups in normal-weight (NW) and obese (OB) individuals. Methods: In 16 extremely OB subjects and 15 NW controls, oxygen uptake (VO2), heart rate (HR), blood lactate (LA) concentration and ratings of perceived exertion (RPE) were determined during submaximal rhythmic exercise at different intensities obtained by increasing the frequency of the movement (FOM) with each machine. Peak VO2 (VO2p) for each equipment was determined with incremental tests up to exhaustion, whereas maximal VO2 was estimated at cycle ergometer. Results: Net energy cost (Enet) of exercise increased (p<0.001) for effect of FOM, in both NW and OB with all equipments. Enet was higher in OB than NW during submaximal exercise with Chest/Back, Shoulder Press/Lat Pull, and Leg Press. Higher VO 2p were attained with lower limbs than with upper limbs, in both NW (p<0.001) and OB (p<0.001). At the same VO2 (relative to maximal), HR, LA, and RPE were similar in NW and OB but higher during arm than leg activity (p<0.001), while at the same VO2 (relative to VO 2p) no difference was detected. Conclusion: Enet of rhythmic exercise is higher in OB than NW with machines requiring wide displacement of large body segments. For both NW and OB, physiological responses and RPE are importantly affected by the relative activation of involved muscles. LA concentration is an important determinant of RPE, independent of the limb in activity. ©2011, Editrice Kurtis.

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