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Arya M. Sharma, Donna L. Goodwin and Janice Causgrove Dunn

Arya Mitra Sharma, MD, FRCPC, is Professor of Medicine at the University of Alberta and Medical Codirector of the Alberta Health Services Obesity Strategy. He is also the Scientific Director of the Canadian Obesity Network. Past appointments include positions as Professor of Medicine and Canada

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Julie Masurier, Marie-Eve Mathieu, Stephanie Nicole Fearnbach, Charlotte Cardenoux, Valérie Julian, Céline Lambert, Bruno Pereira, Martine Duclos, Yves Boirie and David Thivel

Pediatric overweight, obesity, and their multiple associated metabolic complications, are a public health concern, and their alarming progression supports the urgent need for new and effective preventive strategies and weight loss programs. As obese children and adolescents are now five times more

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J. Dru Marshall and Marcel Bouffard

The primary purpose of this study was to document the actual gross movement competencies, as measured by the Test of Gross Motor Development, in obese versus nonobese children. A 2 Gender (male, female) × 2 Groups (obese, nonobese) × 2 Age Categories (Grade 1, Grade 4) × 2 Programs (quality daily physical education [QDPE], non-QDPE) completely randomized factorial design was used. A significant three-way interaction effect (Group × Age × Program) was found for the Locomotor Skills subscale, such that the difference in movement competency in locomotor skills between obese and nonobese children increased as children got older if they did not receive QPDE. A significant main program effect was also found for the Object Control Skills subscale, with the QDPE children scoring higher than the non-QDPE children. It appears, then, that QDPE programs offer a “protective” effect for the development of locomotor skills in obese children. Implications of these findings are discussed.

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G. Lynis Dohm

We previously reported that insulin resistance in skeletal muscle of obese individuals was associated with decreases in insulin signal transduction and tyrosine kinase activity of the insulin receptor. Herein is reviewed the recently published data supporting the hypothesis that protein kinase C (PKC) phosphorylates the insulin receptor on serine/threonine residues to decrease tyrosine kinase activity and cause insulin resistance. Treatment of insulin receptors from obese subjects with alkaline phosphatase restored tyrosine kinase activity, suggesting that the reduced activity was a result of hyperphosphorylation of the receptor. Incubating human muscle fiber strips with PKC inhibitors restored insulin action in muscle of obese patients, while activating PKC with a phorbol ester caused insulin resistance in muscle from lean control patients. The beta isoform of PKC was elevated in muscle of obese, insulin-resistant patients. These data are consistent with the hypothesis that elevated PKC activity may cause insulin resistance by phosphorylating the insulin receptor to decrease tyrosine kinase activity.

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Luke E. Kelly, James H. Rimmer and Richard A. Ness

The purpose of this investigation was to determine the percent body fat of 553 institutionalized mentally retarded adults, ages 18 to 40 yrs, from the Denton State School in Texas. The subjects included 343 males and 210 females. Their percent body fat was estimated with generalized regression equations. Body density for males was measured by the sum of three skinfolds, two girths, and age. Body density for females was measured by the sum of three skinfolds and age. The results from this study revealed that 45.2% of the males and 50.5% of the females were obese. The percent body fat of the female subjects was significantly greater than that of the male subjects. A post hoc analysis revealed that profoundly mentally retarded subjects had significantly lower percent body fat than those subjects functioning at the severe and mild levels. These findings indicate a serious need for more investigation of the caloric intake and expenditure of this population in an institutional environment.

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Shaea A. Alkahtani, Nuala M. Byrne, Andrew P. Hills and Neil A. King

Purpose:

Compensatory responses may attenuate the effectiveness of exercise training in weight management. The aim of this study was to compare the effect of moderate- and high-intensity interval training on eating behavior compensation.

Methods:

Using a crossover design, 10 overweight and obese men participated in 4-week moderate (MIIT) and high (HIIT) intensity interval training. MIIT consisted of 5-min cycling stages at ±20% of mechanical work at 45%VO2peak, and HIIT consisted of alternate 30-s work at 90%VO2peak and 30-s rests, for 30 to 45 min. Assessments included a constant-load exercise test at 45%VO2peak for 45 min followed by 60-min recovery. Appetite sensations were measured during the exercise test using a Visual Analog Scale. Food preferences (liking and wanting) were assessed using a computer-based paradigm, and this paradigm uses 20 photographic food stimuli varying along two dimensions, fat (high or low) and taste (sweet or nonsweet). An ad libitum test meal was provided after the constant-load exercise test.

Results:

Exerciseinduced hunger and desire to eat decreased after HIIT, and the difference between MIIT and HIIT in desire to eat approached significance (p = .07). Exercise-induced liking for high-fat nonsweet food tended to increase after MIIT and decreased after HIIT (p = .09). Fat intake decreased by 16% after HIIT, and increased by 38% after MIIT, with the difference between MIIT and HIIT approaching significance (p = .07).

Conclusions:

This study provides evidence that energy intake compensation differs between MIIT and HIIT.

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Mollie G. DeLozier, Richard G. Israel, Kevin F. O’Brien, Robert A. Shaw and Walter J. Pories

This investigation quantified body composition and aerobic capacity and examined the interrelationships of these measures in 20 morbidly obese females (M age = 34.6 yrs) prior to gastric bypass surgery. Fifteen subjects were hydrostatically weighed at residual lung volume in order to determine body composition. Eighteen subjects performed a maximal modified progressive treadmill test to determine aerobic capacity. Results indicated that the 15 subjects who were weighed hydrostatically were heavier (M wt = 132.34 kg) and fatter (M % fat = 53.18) than any previously described individuals. Relative weight, which is used as a criterion to determine surgery eligibility, was not significantly (p > .05) correlated to percent body fat. Mean aerobic capacity (V̇O2 = 14.99 ml • kg-1 mir-1) was comparable to Class III cardiac patients and was limited by the individuals’ extreme body weight. Since relative weight was shown to be an insensitive measure of obesity, it is recommended that percent fat be measured and used as a means to determine eligibility for gastric bypass surgery. Further study of these individuals is warranted in order to determine what effects large weight loss following surgery will have on parameters of body composition and aerobic capacity. Understanding how large weight loss affects these parameters will aid in designing effective postsurgical exercise rehabilitative programs for future patients.

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Vivian H. Heyward, Kelly L. Cook, Virginia L. Hicks, Kathy A. Jenkins, Joseph A. Quatrochi and Wendy L. Wilson

Three methods of body composition assessment were used to estimate percent body fat (%BF) in nonobese (n=77) and obese (n=71) women, 20-72 yrs of age, Skinfolds (SKF), bioelectrical impedance (BIA), and near-infrared interactance (NIR) methods were compared to criterion-derived %BF from hydrostatic weighing (%BFHW). Nonobese subjects had < 30% BFHW and obese subjects had >30% BFHW. The Jackson, Pollock, and Ward SKF equation and the manufacturer's equations for BIA (Valhalla) and NIR (Futrex-5000) were used. For nonobese women there were no significant differences between mean %BFHW and %BFSKF, %BFB1A, and %BFNIR. The rs and SEEs were 0.65 and 3.4% BF for SKF, 0.61 and 3.6% BF for BIA, and 0.58 and 3.7% BF for NIR for nonobese subjects. For obese women, mean %BPHW was significantly underestimated by the SKF, BIA, and NIR methods. The rs and SEEs for the obese group were 0.59 and 3.4% BF for SKF, 0.56 and 3.5% BF for BIA, and 0.36 and 3.9% BF for NIR. The total errors of the equations ranged from 5.6 to 8.0% BF in the obese group. It is concluded that all three field methods accurately estimate %BF for nonobese women; however, none of the methods is suitable for estimating %BF for obese women.

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Seiji Maeda, Asako Zempo-Miyaki, Hiroyuki Sasai, Takehiko Tsujimoto, Rina So and Kiyoji Tanaka

Obesity and increased arterial stiffness are independent risk factors for cardiovascular disease. Arterial stiffness is increased in obese individuals than in age-matched nonobese individuals. We demonstrated that dietary modification and exercise training are effective in reducing arterial stiffness in obese persons. However, the differences in the effect on arterial stiffness between dietary modification and exercise training are unknown. The purpose of the current study was to compare the effect of dietary modification and aerobic exercise training on arterial stiffness and endothelial function in overweight and obese persons. Forty-five overweight and obese men (48 ± 1 year) completed either a dietary modification (well-balanced nutrient, 1680 kcal/day) or an exercise-training program (walking, 40–60 min/day, 3 days/week) for 12 weeks. Before and after the intervention, all participants underwent anthropometric measurements. Arterial stiffness was measured based on carotid arterial compliance, brachial-ankle pulse wave velocity (baPWV), and endothelial function was determined by circulating level of endothelin-1 (ET-1) and nitric oxide metabolite (nitrites/nitrate as metabolite: NOx). Body mass and waist circumference significantly decreased after both intervention programs. Weight loss was greater after dietary modification than after exercise training (-10.1 ± 0.6 kg vs. -3.6 ± 0.5 kg, p < .01). Although arterial stiffness and the plasma levels of ET-1 and NOx were improved after dietary modification or exercise training, there were no differences in those improvements between the 2 types of interventions. Exercise training improves arterial function in obese men without as much weight loss as after dietary modification.

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Kyu-Jin Lee, Yun-A. Shin, Kyoung-Young Lee, Tae-Won Jun and Wook Song

The purpose of this study was to assess differences in the levels of plasma visfatin among female adolescents and changes in plasma visfatin and insulin resistance in obese female adolescents after 12 wk of aerobic exercise training. Twenty normal-weight female students (body-mass index [BMI] <22.9 kg/m2 and body fat ≤29.9) and 18 obese female students (BMI ≥25 kg/m2 and body fat ≥30%) participated in this study. Eleven obese students were assigned to an exercise group and completed a 12-wk aerobic exercise-training program that included four 40- to 50-min sessions per wk with an energy expenditure of 300–400 kcal/d. Seven obese students were assigned to a control group that received no exercise sessions or dietary restriction. The plasma visfatin levels of obese female adolescents were significantly higher (p < .05) than those of the normal-weight female adolescents. The plasma visfatin levels (294.00 ± 124.74 ng/ml to 185.55 ± 67.30 ng/ml, p < .01) and insulin resistance (p < .05) were significantly reduced after 12 wk of aerobic exercise. The results suggest that aerobic exercise resulting in an energy expenditure of 1,200–1,600 kcal/wk for 12 wk decreases plasma visfatin and insulin resistance in obese female adolescents.