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Marissa A. Kobayashi, Tae Kyoung Lee, Rafael O. Leite, Blanca Noriega Esquives, Guillermo Prado, Sarah E. Messiah and Sara M. St. George

Pediatric obesity in the United States has remained exceedingly high for well over a decade, 1 with ethnic minorities carrying a disproportionate burden of the epidemic compared with their non-Hispanic white counterparts. 2 In particular, Hispanic youth have the highest prevalence of obesity (25

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Kathryn C. Nesbit, Thubi A. Kolobe, Sandra H. Arnold, Susan B. Sisson and Michael P. Anderson

Background:

The purpose of this study was to determine how proximal (home) and distal (neighborhood) environmental characteristics interact to influence obesity in early and middle adolescents.

Methods:

This was a descriptive, cross-sectional study using the 2007 National Survey of Children’s Health (NCSH). Participants were 39,542 children ages 11 to 17 years. Logistic regressions were used to examine the relationship between adolescent obesity and environmental factors, the relative strength of these factors, and the influence of age and gender.

Results:

Proximal environmental factors were stronger correlates of adolescent obesity than distal environmental factors. Sedentary behavior related to TV watching time at home was the strongest correlate of adolescent obesity overall (OR 1.13, 95% CI 1.11–1.15). Parks and playgrounds (OR 0.86, 95% CI 0.08–0.92), as well as recreation centers (OR 0.91, 95% CI 0.85–0.97) were significant distal environmental factor correlates. Girls and middle adolescents were at less risk for obesity than boys and early adolescents (OR 0.51, 95% CI 0.68–0.82; OR 0.75, 95% CI 0.68–0.96).

Conclusion:

The results of this study reveal the importance of proximal environmental characteristics on adolescent obesity relative to distal environmental characteristics. Obesity intervention strategies for adolescents should target sedentary behavior and opportunities for physical activity with a focus on early adolescents and boys.

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Kim D. Lu, Krikor Manoukian, Shlomit Radom-Aizik, Dan M. Cooper and Stanley P. Galant

Obesity increases the risk of asthma throughout life but the underlying mechanisms linking these all too common threats to child health are poorly understood. Acute bouts of exercise, aerobic fitness, and levels of physical activity clearly play a role in the pathogenesis and/or management of both childhood obesity and asthma. Moreover, both obesity and physical inactivity are associated with asthma symptoms and response to therapy (a particularly challenging feature of obesity-related asthma). In this article, we review current understandings of the link between physical activity, aerobic fitness and the asthma-obesity link in children and adolescents (e.g., the impact of chronic low-grade inflammation, lung mechanics, and direct effects of metabolic health on the lung). Gaps in our knowledge regarding the physiological mechanisms linking asthma, obesity and exercise are often compounded by imprecise estimations of adiposity and challenges of assessing aerobic fitness in children. Addressing these gaps could lead to practical interventions and clinical approaches that could mitigate the profound health care crisis of the increasing comorbidity of asthma, physical inactivity, and obesity in children.

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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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Danielle R. Bouchard, K. Ashlee McGuire, Lance Davidson and Robert Ross

One hundred forty-six abdominally obese adults age 60–80 yr were studied to investigate the interaction between cardiorespiratory fitness (CRF) and obesity on functional limitation. Obesity was determined by fat mass (FM), CRF was determined by a maximal treadmill test, and functional limitation was based on 4 different tasks that are predictive of subsequent disability. Both FM (r = –.34, p ≤ .01) and CRF (r = .54, p ≤ .01) were independently associated with functional limitation in bivariate analysis. After further control for sex, age, and the interaction term (CRF × FM), FM was no longer independently associated with functional limitation (p = .10). Analyses were also based on sex-specific tertiles of FM and CRF. The referent group demonstrated significantly lower functional limitation than the low-CRF/low-FM and the low-CRF/high-FM groups (both p ≤ .05). These results highlight the value of recommending exercise for abdominally obese adults.

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Roy J. Shephard

The pediatric sports physician faces an epidemic of obesity. A preliminary triage of individual patients can be based on the body mass index (BMI). The 80th and 95th percentiles of age-specific BMI suggest overweight and obesity, respectively; the diagnosis is confirmed by measurements of triceps and subscapular skinfolds. Over the last twenty years, the proportions of overweight and obese children have increased in both indigenous populations and most developed societies. The increase in body fat content seems to be associated with a decline in daily energy expenditure. Immediate health consequences include an increased prevalence of atherosclerotic plaques, hypertension, and an adverse lipid profile; in addition, the resulting poor self-image limits sport participation. Many obese children become obese adults, facing increased risks of cardiovascular and all-cause deaths. A combination of increased lifestyle activities, behavioral modification techniques to reduce sedentary behavior, and an appropriate diet seems to be the most effective approach to both prevention and treatment of obesity. Such initiatives should be supported by quality daily physical education and changes in the urban environment that encourage an active lifestyle.

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Thiago R.S. Tenório, P. Babu Balagopal, Lars B. Andersen, Raphael M. Ritti-Dias, James O. Hill, Mara C. Lofrano-Prado and Wagner L. Prado

Obesity is a multifactorial disease and its prevalence in children and adolescents has dramatically increased in the past 3 decades ( 31 ). Obesity accelerates the development of various comorbidities leading to reduced life expectancy ( 20 ). In fact, obesity is an independent risk factor for

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Samuel Carvalho Dumith, Virgílio Viana Ramires, Matheus Alves Souza, Daniel Souza Moraes, Fabrício Godoy Petry, Eduardo Soldera Oliveira, Sandro Viana Ramires and Pedro C. Hallal

Background:

Physical fitness is strongly associated with several positive health indicators among adolescents. However, its association with body mass index status is inconsistent. The aim of this study was to explore the association between overweight/obesity and physical fitness among children and adolescents.

Methods:

The design consisted of a cross-sectional study comprising 519 Brazilian students age 7 to 15 years. BMI status was assessed according to sex- and age-specific growth charts. Physical fitness was assessed using 8 tests: sit-and-reach, stationary long jump, 1-minute curl-up, modified pull-up, medicine-ball throw, 9-minute run, 20-m run, and 4-m shuttle-run.

Results:

Prevalence of overweight and obesity was 24% and 12%, respectively. Boys performed better than girls in all tests, except flexibility. Normal weight students performed better than overweight and obese students in all tests, except the sit-and-reach and the medicine-ball throw. Cardiorespiratory fitness had the strongest association with BMI status. The prevalence of obese subjects classified as “most fit” was less than 10%.

Conclusions:

Higher values of body mass index were associated with declines in physical fitness, independent of age. The majority of obese children and adolescents and almost a half of those overweight were classified in the third tertile of physical fitness (least fit).

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Filipe Ricardo Pires de Carvalho, Ana Teresa da Conceição Figueira Martins and Ana Maria Miranda Botelho Teixeira

In spite of the advances in knowledge on the multi–factorial nature of obesity, many questions related to the consequences of the disease continue to be unanswered. Several studies have reported biomechanic and kinematic adaptation and alterations in walking and in tasks of every day life, motivated by the additional load of fat mass in children and adults. The main objective of this study was to understand the effect of obesity in the electromyographic activity of four lower extremity muscles during three speeds of walking and during a countermovement jump (CMJ) in twenty two (9 obese and 13 normal weight) female adolescents aged 13. Although electromyographic differences were not observed between groups for normal, slow and fast speeds, data suggests that the preferred pace of the obese is less efficient than that of the normal weight group. In CMJ task, differences in the after–fall jump phase were observed. More studies are needed to explain if the few differences observed between groups are caused by the bigger amount of fat mass.

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Athanasios Z. Jamurtas, Antonios Stavropoulos-Kalinoglou, Stilianos Koutsias, Yiannis Koutedakis and Ioannis Fatouros

Childhood obesity is increasing alarmingly, and a strong association with chronic diseases has been established. Specific adipokines are released from the adipose tissue and relate with chronic diseases even in the pediatric population. Adiponectin levels are lower in obesity and increase with decreasing body weight. A few pediatric studies examining a possible relationship between resistin and obesity do not provide a clear picture. Most studies agree that visfatin levels appear elevated in childhood obesity. Exercise seems to increase adiponectin levels whereas resistin levels are reduced. The lack of data on the effects of acute and chronic exercise on visfatin levels precludes us from making safe conclusions as to what the effects of exercise (acute or chronic) would be on visfatin levels in children. Clearly, exercise has an impact on the adipose tissue and the release of adiponectin, resistin, and visfatin. However, other factors affect the secretion rate of these adipokines from the adipose tissue; these factors should also be taken into consideration when examining the effects of exercise on adipokines. Gender, age, body composition, physical activity levels, mode and intensity of exercise are some of the factors that should be looked into in future studies.