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Soyang Kwon, Trudy L. Burns and Kathleen Janz

Background:

This study aimed to examine combined and independent effects of cardiorespiratory fitness and fatness on cardiovascular risk factors among U.S. adolescents.

Methods:

Data from adolescents age 12 to 19 years participating in the NHANES 1999 to 2002 were used. Fitness level was determined by submaximal treadmill test and was dichotomized as ‘not fit’ or ‘fit’ according to the FITNESSGRAM. Fatness level was categorized as ‘not fat’ or ‘fat’ based on the CDC BMI growth charts. Gender-specific multivariable linear regression analyses were conducted to compare age-, race/ethnicity-, fatness-, and waist circumference-adjusted means of blood pressure, lipids, lipoproteins, C-peptide, insulin, and C-reactive protein (CRP) levels.

Results:

A total of 3202 adolescents (1629 boys) were included for data analysis. Among boys, total cholesterol, tri-glycerides, insulin, and CRP mean levels were significantly higher (P < .05) in the ‘not fit’ group than in the ‘fit’ group, after adjustment for fatness level and waist circumference. Among girls, the fatness level- and waist circumference-adjusted means of total cholesterol (P < .01) and LDL-C (P < .09) were higher in the ‘not fit’ than ‘fit’ groups.

Conclusion:

Cardiorespiratory fitness, independent of fatness, may have beneficial effects on lipid profiles among girls, and on lipid profiles, insulin metabolism, and inflammation levels among boys.

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Sunhyo Jeong and Michung Yoon

Ovariectomy leads to weight gain primarily in the form of adipose tissue in rodents. The authors investigated whether swimming improves ovariectomy-induced obesity through activation of peroxisome proliferatoractivated receptor α (PPARα) in the skeletal muscle of female ovariectomized (OVX) mice, an animal model of postmenopausal women. Female mice were randomly divided into 3 groups (n = 8/group): a sedentary sham-operated group, a sedentary OVX group, and a swim-trained OVX group. After mice were subjected to swim training or kept sedentary for 6 wk, the authors studied the effects of swimming on not only bodyweight gain, white adipose tissue (WAT) mass, adipocyte size, and skeletal-muscle lipid accumulation but also the expression of skeletal-muscle PPARα target genes. Sedentary OVX mice had significantly higher body weight and WAT than sedentary sham mice. However, swim training reduced body-weight gain, WAT mass, and adipocyte size of OVX mice. Swim-trained OVX mice had significantly lower levels of serum triglycerides and total cholesterol than sedentary OVX mice. Lipid accumulation in skeletal muscle was also markedly decreased by swimming. Concomitantly, swim training significantly increased mRNA levels of skeletal-muscle PPARα and its target enzymes, as well as uncoupling protein 3 (UCP3) responsible for fattyacid oxidation. These results suggest that swimming can effectively prevent weight gain, adiposity, adipocyte hypertrophy, and lipid disorders caused by ovariectomy, in part through the activation of PPARα and UCP3, in the skeletal muscle of female mice and may contribute to the alleviation of metabolic syndrome, including obesity, hyperlipidemia, and Type 2 diabetes in postmenopausal women.

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Elsa Heyman, Christelle Toutain, Paul Delamarche, Phanélie Berthon, David Briard, Hala Youssef, Marc DeKerdanet and Arlette Gratas-Delamarche

Sixteen postmenarcheal Type 1 diabetic adolescent girls were randomized into training (involving aerobic and strength exercises) and nontraining groups. Body composition (skinfold thickness), aerobic fitness (PWC170), plasma lipids, serum apolipoproteins, lipoprotein(a), leptin, and adiponectin were assessed before and after the 6-month period. After the 6-month period, fat mass and leptin increased significantly in the nontraining group but not in the training group. Conversely, in the latter group, fat-free mass increased (P < .01). Moreover, PWC170 improved and apolipoproteinB:apolipoproteinA-1 ratio decreased with physical training (P < .05). Thus, physical training reduces cardiovascular risks and the increase of insulin resistance risk factors in diabetic adolescent girls.

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Kevin A. Jacobs, David R. Paul, Ray J. Geor, Kenneth W. Hinchcliff and W. Michael Sherman

The purpose of the current study was to examine the influence of dietary composition on short-term endurance training–induced adaptations of substrate partitioning and time trial exercise performance. Eight untrained males cycled for 90 min at ~54% aerobic capacity while being infused with [6,62H]glucose before and after two 10-d experimental phases separated by a 2-week washout period. Time trial performance was measured after the 90-min exercise trials before and after the 2nd experimental phase. During the first 10-d phase, subjects were randomly assigned to consume either a high carbohydrate or high fat diet while remaining inactive (CHO or FAT). During the second 10-d phase, subjects consumed the opposite diet, and both groups performed identical daily supervised endurance training (CHO+T or FAT+T). CHO and CHO+T did not affect exercise metabolism. FAT reduced glucose flux at the end of exercise, while FAT+T substantially increased whole body lipid oxidation during exercise and reduced glucose flux at the end of exercise. Despite these differences in adaptation of substrate use, training resulted in similar improvements in time trial performance for both groups. We conclude that (a) 10-d high fat diets result in substantial increases in whole body lipid oxidation during exercise when combined with daily aerobic training, and (b) diet does not affect short-term training-induced improvements in high-intensity time trial performance.

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Masato Suzuki, Daisuke Shindo, Masaki Kimura and Hidefumi Waki

This study was conducted to assess the effects of exercise, diet, and their combination on metabolic syndrome (MS) risk factors including visceral fat mass (VFM), glucose intolerance, and dyslipidemia in OLETF rats. Thirty-two male rats were assigned to exercise (OLETF-Ex), dietary treatment (-DT), combination (-Ex&DT), or sedentary (-Sed) groups. Daily voluntary exercise using a rotary wheel was performed in OLETF-Ex. Each treatment was conducted from 21 to 31 wk of age. An oral glucose tolerance test was performed before and after the treatment period. Absolute levels of VFM, subcutaneous fat mass (SFM), and serum lipids including triglyceride, total cholesterol, and LDL-cholesterol (LDL-C) were measured after the treatment period. All therapeutic treatments resulted in significantly lower levels of body weight, VFM, SFM, and serum lipids than in sedentary control rats. All therapeutic treatments were also found to improve indices of oral glucose tolerance. Of the 3 therapeutic treatments, serum LDL-C levels were significantly lower in OLETF-Ex and OLETF-Ex&DT than in OLETF-Sed. The data demonstrate that all therapeutic approaches tested were effective in improving a number of MS-related parameters in OLETF rats. However, exercise-based therapeutic intervention may provide additional benefits for improving fat metabolism in MS patients.

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Melinda M. Manore, Janice Thompson and Marcy Russo

This study presents the diet and exercise strategies of a world-class bodybuilder during an 8-week precompetition period. Weighed food records were kept daily, and body fat, resting metabolic rate (RMR), VO2max, blood lipids, and liver enzymes were measured. Two hrs of aerobic exercise and 3 hrs of weight training were done daily 6 daystweek. Mean energy intake was 4,952 kcallday (54 kcallkg) and included 1,278 kcallday from mediumchain triglycerides (MCT). Diet without MCT provided 76% of energy from carbohydrate, 19% from protein (1.9 g proteiag), and 5% from fat. Micronutrients were consumed at ≥ 100% of the RDA, except for zinc and calcium, without supplementation. Mean RMR was 2,098 kcallday and represented 43% of energy intake. VO2max was 53 ml.kg−1.min−1. Underwater weighing showed that body fat decreased from 9% to 7%. Blood lipids were normal, but two liver enzymes were elevated (alanine and aspartate aminotransferase). This world-class bodybuilder achieved body fat goals by following a nutrient dense, high energy, high carbohydrate diet and an exercise program that emphasized both aerobic and anaerobic metabolism.

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Randhall B. Carteri, André Luis Lopes, Cinthia M. Schöler, Cleiton Silva Correa, Rodrigo C. Macedo, Júlia Silveira Gross, Renata Lopes Kruger, Paulo I. Homem de Bittencourt Jr and Álvaro Reischak-Oliveira

Background:

Since exercise increases the production of reactive oxygen species in different tissues, the objective of this study is to evaluate, compare and correlate the acute effects of aerobic and resistance exercise in circulatory markers of oxidative stress and acylated ghrelin (AG) in postmenopausal women.

Methods:

Ten postmenopausal women completed different protocols: a control session (CON), an aerobic exercise session (AERO); and a single-set (SSR) or 3-set (MSR) resistance exercise protocol.

Results:

After exercise, both MSR (P = .06) and AERO (P = .02) sessions showed significant increased lipid peroxidation compared with baseline levels. CON and SSR sessions showed no differences after exercise. No differences were found between sessions at any time for total glutathione, glutathione dissulfide or AG concentrations.

Conclusions:

Exercise significantly increased lipid peroxidation compared with baseline values. As pro oxidant stimuli is necessary to promote chronic adaptations to the antioxidant defenses induced by exercise, our findings are important to consider when evaluating exercise programs prescription variables aiming quality of life in this population.

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John Quindry, Lindsey Miller, Graham McGinnis, Brian Kliszczewiscz, Dustin Slivka, Charles Dumke, John Cuddy and Brent Ruby

Previous research findings indicate that environmental temperature can influence exercise-induced oxidative-stress responses, although the response to variable temperatures is unknown. The purpose of this study was to investigate the effect of warm, cold, and “neutral,” or room, environmental temperatures on the blood oxidative stress associated with exercise and recovery. Participants (N = 12, age 27 ± 5 yr, VO2max = 56.7 ± 5.8 ml · kg-1 · min-1, maximal cycle power output = 300 ± 39 W) completed 3 exercise sessions consisting of a 1-hr ride at 60% Wmax, at 40% relative humidity in warm (33 °C), cold (7 °C), and room-temperature environments (20 °C) in a randomized crossover fashion. Rectal core temperature was monitored continually as participants remained in the respective trial temperature throughout a 3-hr recovery. Blood was collected preexercise and immediately, 1 hr, and 3 hr postexercise and analyzed for oxidative-stress markers including ferric-reducing ability of plasma (FRAP), Trolox-equivalent antioxidant capacity (TEAC), lipid hydroperoxides, and protein carbonyls. Core temperature was significantly elevated by all exercise trials, but recovery core temperatures reflected the given environment. FRAP (p < .001), TEAC (p < .001), and lipid hydroperoxides (p < .001) were elevated after warm exercise while protein carbonyls were not altered (p > .05). These findings indicate that moderate-intensity exercise and associated recovery in a warm environment elicits a blood oxidative-stress response not observed at comparable exercise performed at lower temperatures.

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Antonio Paoli, Giuseppe Marcolin, Fabio Zonin, Marco Neri, Andrea Sivieri and Quirico F. Pacelli

Exercise and nutrition are often used in combination to lose body fat and reduce weight. In this respect, exercise programs are as important as correct nutrition. Several issues are still controversial in this field, and among them there are contrasting reports on whether training in a fasting condition can enhance weight loss by stimulating lipolytic activity. The authors’ purpose was to verify differences in fat metabolism during training in fasting or feeding conditions. They compared the effect on oxygen consumption (VO2) and substrate utilization, estimated by the respiratory-exchange ratio (RER), in 8 healthy young men who performed the same moderate-intensity training session (36 min of cardiovascular training on treadmill at 65% maximum heart rate) in the morning in 2 tests in random sequence: FST test (fasting condition) without any food intake or FED test (feeding condition) after breakfast. In both cases, the same total amount and quality of food was assumed in the 24 hr after the training session. The breakfast, per se, increased both VO2 and RER significantly (4.21 vs. 3.74 and 0.96 vs. 0.84, respectively). Twelve hours after the training session, VO2 was still higher in the FED test, whereas RER was significantly lower in the FED test, indicating greater lipid utilization. The difference was still significant 24 hr after exercise. The authors conclude that when moderate endurance exercise is done to lose body fat, fasting before exercise does not enhance lipid utilization; rather, physical activity after a light meal is advisable.

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Henrique Nascimento, Ana Inês Alves, Ana Filipa Medeiros, Susana Coimbra, Cristina Catarino, Elsa Bronze-da-Rocha, Elísio Costa, Petronila Rocha-Pereira, Gustavo Silva, Luísa Aires, André Seabra, Jorge Mota, Helena Ferreira Mansilha, Carla Rêgo, Alice Santos-Silva and Luis Belo

Purpose:

There are few reliable studies assessing the effect of physical exercise (PE) on adipokines levels at young ages. Our objective was to study the effects of regular PE on plasma adipokines in pediatric overweight and obesity.

Method:

117 overweight and obese children and adolescents (47% females; 10.2 years) participated in an 8-month longitudinal study divided in two groups: PE group (n = 80), engaged in an after-school PE program; control group (n = 37), with no PE program. Plasma lipids, C-reactive protein (CRP), adiponectin, resistin, leptin, IL-6, IL-1beta, TNF-alpha, insulin and glucose levels were determined.

Results:

contrarily to the control group, the PE group presented reductions in body mass index z-score (BMIzsc) and body fat percentage that were accompanied by an improvement in lipid profile and insulin resistance, a reduction in CRP and TNF-alpha and an increase in adiponectin levels. The reductions in BMIzsc were inversely correlated with changes in adiponectin (r=−0.329, p = .003) and positively correlated with changes in percentage body fat (r = .262, p = .032), triglycerides (r = .228, p = .042) and leptin (r = .285, p = .010).

Conclusion:

Moderate reductions in adiposity improve proinflammatory status in obese children and adolescents. A more substantial reduction in BMIzsc was associated with a greater increment in adiponectin and reduction in leptin.