Search Results

You are looking at 91 - 100 of 1,434 items for :

Clear All
Restricted access

Brian D. Tran, Szu-Yun Leu, Stacy Oliver, Scott Graf, Diana Vigil and Pietro Galassetti

Pediatric obesity typically induces insulin resistance, often later evolving into type 2 diabetes. While exercise, enhancing insulin sensitivity, is broadly used to prevent this transition, it is unknown whether alterations in the exercise insulin response pattern occur in obese children. Therefore, we measured exercise insulin responses in 57 healthy weight (NW), 20 overweight (OW), and 56 obese (Ob) children. Blood samples were drawn before and after 30min of intermittent (2min on, 1min off) cycling at ~80% VO2max. In a smaller group (14 NW, 6 OW, 15 Ob), a high-fat meal was ingested 45 min preexercise. Baseline glycemia was similar and increased slightly and similarly in all groups during exercise. Basal insulin (pmol/L) was significantly higher in Ob vs. other groups; postexercise, insulin increased in NW (+7 ± 3) and OW (+5 ± 8), but decreased in Ob (−15 ±5, p < .0167 vs. NW). This insulin drop in Ob was disproportionately more pronounced in the half of Ob children with higher basal insulin (Ob-H). In all groups, high-fat feeding caused a rapid rise in insulin, promptly corrected by exercise. In Ob, however, insulin rose again 30 min postexercise. Our data indicates a distinct pattern of exercise-induced insulin modulation in pediatric obesity, possibly modulated by basal insulin concentrations.

Restricted access

Andrea T. Duran, Erik Gertz, Daniel A. Judelson, Andrea M. Haqq, Susan J. Clark, Kavin W. Tsang and Daniela Rubin

Prader-Willi Syndrome (PWS), the best characterized form of syndromic obesity, presents with abnormally high fat mass. In children, obesity presents with low-grade systemic inflammation. This study evaluated if PWS and/or nonsyndromic obesity affected cytokine responses to intermittent aerobic exercise in children. Eleven children with PWS (11 ± 2 y, 45.4 ± 9.5% body fat), 12 children with obesity (OB) (9 ± 1 y, 39.9 ± 6.8% body fat), and 12 lean (LN) children (9 ± 1 y, 17.5 ± 4.6% body fat) participated. Children completed 10 2-min cycling bouts of vigorous intensity, separated by 1-min rest. Blood samples were collected preexercise (PRE), immediately postexercise (IP), and 15, 30, and 60 min into recovery to analyze possible changes in cytokines. In all groups, IL-6 and IL-8 concentrations were greater during recovery compared with PRE. PWS and OB exhibited higher IL-6 area under the curve (AUC) than LN (p < .01 for both). PWS demonstrated higher IL-8 AUC than LN (p < .04). IL-10, TNF-α, and IFN-γ did not change with exercise (p > .05 for all). Results indicate that children with PWS respond with increased Il-6 and IL-8 concentrations to acute exercise similarly to controls. Excess adiposity and epigenetic modifications may explain the greater integrated IL-6 and IL-8 responses in PWS compared with controls.

Restricted access

Paul A. McAuley, Haiying Chen, Duck-chul Lee, Enrique Garcia Artero, David A. Bluemke and Gregory L. Burke

Background:

The influence of higher physical activity on the relationship between adiposity and cardiometabolic risk is not completely understood.

Methods:

Between 2000–2002, data were collected on 6795 Multi-Ethnic Study of Atherosclerosis (MESA) participants. Self-reported intentional physical activity in the lowest quartile (0–105 MET-minutes/week) was categorized as inactive and the upper three quartiles (123–37,260 MET-minutes/week) as active. Associations of body mass index (BMI) and waist circumference categories, stratified by physical activity status (inactive or active) with cardiometabolic risk factors (dyslipidemia, hypertension, upper quartile of homeostasis model assessment of insulin resistance [HOMA-IR] for population, and impaired fasting glucose or diabetes) were assessed using logistic regression analysis adjusting for age, gender, race/ethnicity, and current smoking.

Results:

Among obese participants, those who were physically active had reduced odds of insulin resistance (47% lower; P < .001) and impaired fasting glucose/diabetes (23% lower; P = .04). These associations were weaker for central obesity. However, among participants with a normal waist circumference, those who were inactive were 63% more likely to have insulin resistance (OR [95% CI] 1.63 [1.24–2.15]) compared with the active reference group.

Conclusions:

Physical activity was inversely related to the cardiometabolic risk associated with obesity and central obesity.

Restricted access

Anders Lindelof, Claus Vinther Nielsen and Birthe D. Pedersen

Background:

Individuals’ attitude toward physical activity may contribute to their willingness to participate in such behavior. This study qualitatively and longitudinally explored obese adolescents’ attitudes to physical activity.

Methods:

Fifteen obese adolescents were recruited at a weight loss camp. Participants were followed for 2.5 years with 3 yearly rounds of participant observations and interviews. Data were analyzed using a phenomenological-hermeneutic approach.

Results:

Four categories were identified: 1) throughout the study participants became more sedentary as they de-selected activities like bike riding; 2) participants did not perceive their increasing inactive lifestyle as hindering weight loss as they consider such activities as futile compared with vigorously hard exercise; 3) participants frequently failed to participate in hard exercise, like going to the gym; and 4) participants had a genuine antipathy against being physical active.

Conclusions:

Among others, a reason why obese adolescents fail to live an active life is that they find limited pleasure in such behavior. It is argued that obese adolescents need a positive attitude toward physical activity if they are to be more active. With reference to Bourdieu’s theory of practice, it is hypothesized that such attitude needs to be learned through everyday life by experiencing joy and meaning by being physical active.

Restricted access

Humberto José Gomes Silva, Lars Bo Andersen, Mara Cristina Lofrano-Prado, Mauro V.G. Barros, Ismael Fortes Freitas Jr., James Hill and Wagner Luiz do Prado

Background:

It is unclear how different exercise intensities affect cardiovascular disease (CVD) risk factors in obese adolescents. The aim of this study was to compare the effects of high-intensity (HIT) vs. low-intensity (LIT) aerobic training on CVD risk factors in obese adolescents.

Methods:

Forty-three obese adolescents (age: 15.7 ± 1.3 years, BMI: 34.3 ± 4.1kg/m2) participated this study either HIT (corresponding to ventilatory threshold I; N = 20) or LIT (20% below ventilatory threshold I; N = 23) for 12 weeks. All sessions were isocaloric (350 kcal). All participants received the same nutritional, psychological, and clinical counseling. Subjects were assessed in fatness, fitness, lipid profile, and glucose at baseline and after 12 weeks. The CVD risk factors assessed were waist circumference (WC), total cholesterol (TC), high-density lipoprotein (HDL), glucose, and fitness, which were single and clustered analyzed (z scores sum).

Results:

Body mass, Body Mass Index, fatness, and WC were improved (P < .001) in both groups. The sum of z scores (WC + TC + glucose-fitness-HDL) improved in both HIT (12 weeks = −2.16 SD; Cohen’s d = .45) and LIT (12 weeks = −2.13 SD; Cohen’s d = .60) without groups differences. Changes in fitness were associated with changes in WC (r = −.48; P = .003).

Conclusion:

HIT does not promote any additional improvements in CVD risk factors than LIT in obese adolescents.

Restricted access

Katrin A. Dias, Concetta E Masterson, Matthew P. Wallen, Arnt E. Tjonna, Mansoureh S. Hosseini, Peter S.W. Davies, Peter A. Cain, Gary M. Leong, Ross Arena, Charlotte B. Ingul and Jeff S. Coombes

Purpose:

Poor cardiorespiratory fitness is associated with increased all cause morbidity and mortality. In children with obesity, maximum oxygen uptake (V̇O2max) may not be achieved due to reduced motivation and peripheral fatigue. We aimed to identify a valid submaximal surrogate for V̇O2max in children with obesity.

Method:

Ninety-two children with obesity (7–16 years) completed a maximal exercise treadmill test and entered a three-month exercise and/or nutrition intervention after which the exercise test was repeated (n = 63). Participants were required to reach V̇O2max to be included in this analysis (n = 32 at baseline and n = 13 at both time-points). The oxygen uptake efficiency slope (OUES) was determined as the slope of the line when V̇O2 (L/min) was plotted against log V̇E. Associations between the maximal OUES, submaximal OUES (at 3, 4, 5 and 6 min of the exercise test) and V̇O2max were calculated.

Results:

In the cross-sectional analysis, V̇O2max (L/min) was strongly correlated with 5-min OUES independent of Tanner puberty stage and sex (R 2 = .80, p < .001). Longitudinal changes in V̇O2max were closely reflected by changes in 5-min OUES independent of change in percent body fat (R 2 = .63, p < .05).

Conclusion:

The 5-min OUES is a viable alternative to V̇O2max when assessing children with obesity.

Restricted access

Paulo Farinatti, Silvio Rodrigues Marques Neto, Ingrid Dias, Felipe A. Cunha, Eliete Bouskela and Luiz G. Kraemer-Aguiar

Purpose:

Cardiac autonomic dysfunction (CADysf) in children is often associated to obesity and may be attenuated by physical activity. In this study, we investigated the effects of resistance training (RT) upon CADysf assessed by heart rate variability (HRV) in obese adolescents.

Method:

Volunteers were assigned into groups according to standard deviation scores for body mass index (z-BMI) and percentile for age and sex: obese (OB; z-BMI from 2 to 3 and ≥ 95th percentile, n = 24) and normal weight controls (CG; z-BMI from -2–1 and < 85th percentile, n = 20). OB performed isolated RT during 12 weeks [3 sets of 6–10reps with 70–85% 10RM]. Waist circumference, systolic/diastolic blood pressures (SBP/DBP), lipids, and HRV were assessed at baseline. Only OB underwent postintervention assessments.

Results:

At baseline, SBP (122.4 ± 9.1 vs. 109.7 ± 11.5 mmHg, p < .001) and DBP (76.1 ± 7.1 vs. 65.3 ± 5.9 mmHg, p < .001) were higher, while parasympathetic HRV indexes were lower (p < .05) in OB compared with CG. After RT, waist circumference (3%, p < .001) and SBP (10%, p < .001) reduced in OB. Parasympathetic indexes of HRV increased in OB (SDNN: 25%, p = .03; rMSSD: 48%, p = .0006; pNN50: 67%, p = .001; total power: 54%, p = .01; HF: 101%, p = .001) and baseline differences between groups for sympathetic and parasympathetic activities were no longer observed after RT.

Conclusion:

RT attenuated CAdyfs and BP in obese adolescents, by increasing parasympathetic activity and decreasing sympatho-vagal balance.

Restricted access

David W. Brock, Olivia Thomas, Charles D. Cowan, David B. Allison, Glenn A. Gaesser and Gary R. Hunter

Background:

Numerous public health organizations have adopted national physical activity recommendations. Despite these recommendations, over half of the US population does not meet the minimum recommendation for physical activity, with large variations across individual US states.

Methods:

Using the 2005 Behavioral Risk Factor Surveillance System (BRFSS) prevalence data for physical activity and obesity by state, we performed a weighted least squares regression using prevalence of obesity (BMI ≥ 30 kg/m2) as the dependent variable and insufficiently physically active (included completely sedentary), age, race, gender, and median household income as the independent variables.

Results:

The unadjusted weighted least squares regression revealed a strong correlation between a state’s prevalence of obesity and the prevalence of insufficiently physically active (R = .76, R 2 = .58, P < .0001). After adjusting for age, gender, race, and median household income, the prevalence of insufficiently physically active is still a significant predictor of the state prevalence of obesity (partial R = .44, R 2 = .19 P = .004).

Conclusion:

Macroenvironmental and sociopolitical disparities between individual US states that transcend simple state-level demographic factors need to be examined more rigorously to identify unique barriers and promoters of physical activity.

Restricted access

Jun-Hyun Kim, Chanam Lee, Norma E. Olvera and Christopher D. Ellis

Background:

Childhood obesity and its comorbidities have become major public health challenges in the US. While previous studies have investigated the roles of land uses and transportation infrastructure on obesity, limited research has examined the influence of landscape spatial patterns. The purpose of this study was to examine the association between landscape spatial patterns and obesity in Hispanic children.

Methods:

Participants included 61 fourth- and fifth-grade Hispanic children from inner-city neighborhoods in Houston, TX. BMI z-scores were computed based on objectively-measured height and weight from each child. Parental and child surveys provided sociodemographic and physical activity data. Landscape indices were used to measure the quality of landscape spatial patterns surrounding each child’s home by utilizing Geographic Information Systems and remote sensing analyses using aerial photo images.

Results:

After controlling for sociodemographic factors, in the half-mile airline buffer, more tree patches and well-connected landscape patterns were negatively correlated with their BMI z-scores. Furthermore, larger sizes of urban forests and tree patches were negatively associated with children’s BMI z-scores in the half-mile network buffer assessment.

Conclusions:

This study suggests that urban greenery requires further attention in studies aimed at identifying environmental features that reduce childhood obesity.

Restricted access

David R. Bassett, John Pucher Jr., Ralph Buehler, Dixie L. Thompson and Scott E. Crouter

Purpose:

This study was designed to examine the relationship between active transportation (defined as the percentage of trips taken by walking, bicycling, and public transit) and obesity rates (BMI ≥ 30 kg · m−2) in different countries.

Methods:

National surveys of travel behavior and health indicators in Europe, North America, and Australia were used in this study; the surveys were conducted in 1994 to 2006. In some cases raw data were obtained from national or federal agencies and then analyzed, and in other cases summary data were obtained from published reports.

Results:

Countries with the highest levels of active transportation generally had the lowest obesity rates. Europeans walked more than United States residents (382 versus 140 km per person per year) and bicycled more (188 versus 40 km per person per year) in 2000.

Discussion:

Walking and bicycling are far more common in European countries than in the United States, Australia, and Canada. Active transportation is inversely related to obesity in these countries. Although the results do not prove causality, they suggest that active transportation could be one of the factors that explain international differences in obesity rates.