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Relationships between Obesity, Cardiorespiratory Fitness, and Cardiovascular Function  [PDF]
Kade Davison,Stefan Bircher,Alison Hill,Alison M. Coates,Peter R. C. Howe,Jonathan D. Buckley
Journal of Obesity , 2010, DOI: 10.1155/2010/191253
Abstract: Background. Obesity and low cardiorespiratory fitness (CRF) have been shown to independently increase the risk of CVD mortality. The aim of this study was to investigate the relationship between CRF, body fatness and markers of arterial function. Method and Results. Obese (9 male, 18 female; BMI 35.3 ± 0.9 kg·m-2) and lean (8 male, 18 female; BMI 22.5 ± 0.3?kg·m-2) volunteers were assessed for body composition (DXA), cardiorespiratory fitness (predicted max), blood pressure (BP), endothelial vasodilatator function (FMD), and arterial compliance (AC) (via radial artery tonometry). The obese group had more whole body fat and abdominal fat (43.5 ± 1.2% versus 27.2 ± 1.6%; and 48.6 ± 0.9% versus 28.9 ± 1.8%; resp.), and lower FMD (3.2 ± 0.4% versus 5.7 ± 0.7%; ) than the lean subjects, but there was no difference in AC. AC in large arteries was positively associated with CRF ( ; ) but not with fatness. Conclusion. These results indicate distinct influences of obesity and CRF on blood vessel health. FMD was impaired with obesity, which may contribute to arterial and metabolic dysfunction. Low CRF was associated with reduced elasticity in large arteries, which could result in augmentation of aortic afterload. 1. Introduction Obesity and cardiorespiratory fitness (CRF) are independent predictors of cardiovascular (CV) and all-cause mortality [1–5]. Furthermore, it appears that CRF may be protective against the cardiovascular risk associated with obesity [6]. The mechanisms which mediate the relationships between obesity, CRF, and CV mortality risk are not entirely understood [5, 7]. However, given that the protective effects of CRF and the detrimental effects of obesity appear to influence CV mortality independently of other CV risk factors, it is of interest to investigate their influences on established markers of subclinical CV function. This will allow for a better understanding of the potential mechanisms by which obesity and CRF may influence the risk of CV mortality. Increased adiposity, in particular visceral adiposity, is associated with reduced vascular endothelial function [8, 9]. Endothelial function refers to the general functional capacity of vascular endothelial cells, primarily mediated by their capacity to synthesize and release nitric oxide (NO) [10]. Reduced synthesis and/or availability of NO is associated with increased vascular permeability, inflammation, adhesion and thrombosis, and a reduced vasodilatory capacity, and abnormalities of endothelial function have been associated with a number of CV risk factors [11]. The noninvasive
Relationships between Obesity, Cardiorespiratory Fitness, and Cardiovascular Function  [PDF]
Kade Davison,Stefan Bircher,Alison Hill,Alison M. Coates,Peter R. C. Howe,Jonathan D. Buckley
Journal of Obesity , 2010, DOI: 10.1155/2010/191253
Abstract: Background. Obesity and low cardiorespiratory fitness (CRF) have been shown to independently increase the risk of CVD mortality. The aim of this study was to investigate the relationship between CRF, body fatness and markers of arterial function. Method and Results. Obese (9 male, 18 female; BMI 35.3 ± 0.9 kg·m-2) and lean (8 male, 18 female; BMI 22.5 ± 0.3 kg·m-2) volunteers were assessed for body composition (DXA), cardiorespiratory fitness (predicted ?VO2max), blood pressure (BP), endothelial vasodilatator function (FMD), and arterial compliance (AC) (via radial artery tonometry). The obese group had more whole body fat and abdominal fat (43.5 ± 1.2% versus 27.2 ± 1.6%; <.001 and 48.6 ± 0.9% versus 28.9 ± 1.8%; <.001, resp.), and lower FMD (3.2 ± 0.4% versus 5.7 ± 0.7%; <.01) than the lean subjects, but there was no difference in AC. AC in large arteries was positively associated with CRF (R=0.5; <.01) but not with fatness. Conclusion. These results indicate distinct influences of obesity and CRF on blood vessel health. FMD was impaired with obesity, which may contribute to arterial and metabolic dysfunction. Low CRF was associated with reduced elasticity in large arteries, which could result in augmentation of aortic afterload.
Association of Low Muscle Mass and Combined Low Muscle Mass and Visceral Obesity with Low Cardiorespiratory Fitness  [PDF]
Tae Nyun Kim, Man Sik Park, You Jeong Kim, Eun Ju Lee, Mi-Kyung Kim, Jung Min Kim, Kyung Soo Ko, Byoung Doo Rhee, Jong Chul Won
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0100118
Abstract: Objective Previous studies have shown that low cardiorespiratory fitness (CRF), visceral obesity and low muscle mass may share pathophysiological mechanisms, such as insulin resistance and chronic inflammation. In this study, we investigated whether low CRF is associated with low muscle mass, visceral obesity, and visceral obesity combined with low muscle mass. Research Design and Methods The associations between CRF and low muscle mass and combined low muscle mass and visceral obesity were examined in 298 apparently healthy adults aged 20–70 years. Low muscle mass was defined using a skeletal muscle mass index (SMI) that was calculated using dual energy X-ray absorptiometry. Visceral obesity was defined as a visceral fat area (VFA) exceeding 100 cm2 in women and 130 cm2 in men. We classified the participants into 4 low muscle mass/visceral obesity groups according to SMI and VFA. CRF was measured using a cycle ergometer test. Results CRF level correlated positively with SMI and negatively with VFA. Individuals with low muscle mass had lower CRF values than those without low muscle mass. After adjustment for age, sex, lifestyle factors, and markers for insulin resistance and inflammation, participants in the lowest quartile of CRF had an odds ratio (OR) for low muscle mass of 4.98 compared with those in the highest quartile (95% confidence interval (CI) = 1.19–12.99; P for trend = 0.001) and an OR for combined low muscle mass and visceral obesity of 31.46 (95% CI = 4.31–229.68; P for trend = 0.001). Conclusions Individuals with lower CRF exhibited increased risk of low muscle mass and combined low muscle mass and visceral obesity. These results suggest that low CRF may be a potential indicator for low muscle mass and combined low muscle mass and visceral obesity in Korean adults.
Indices of Abdominal Adiposity and Cardiorespiratory Fitness Test Performance in Middle-School Students  [PDF]
Ryan Burns,James C. Hannon,Timothy A. Brusseau,Barry Shultz,Patricia Eisenman
Journal of Obesity , 2013, DOI: 10.1155/2013/912460
Abstract: Background. Previous research suggests that use of BMI as a screening tool to assess health in youth has limitations. Valid alternative measures to assess body composition are needed to accurately identify children who are aerobically fit, which is an indicator of health status. The purpose of this study was to examine the associations between select anthropometric measures and cardiorespiratory fitness test performance in middle-school students. Methods. Participants included 134 students (65 boys and 69 girls) recruited from the 6th, 7th, and 8th grades. Anthropometric measures consisted of BMI, waist circumference (WC), waist-to-height ratio (WHtR), and percent body fat estimated from two-site skinfolds (%BF-SKF), as well as the hand-held OMRON BIA device (%BF-BIA). Cardiorespiratory fitness tests included the one-mile run and PACER test. Data were collected on four separate testing days during the students’ physical education classes. Results. There were statistically significant moderate correlations between the %BF estimations, WHtR, and cardiorespiratory fitness test scores in both genders . BMI at best only displayed weak correlations with the cardiorespiratory fitness test scores. Conclusions. The results suggest that alternative measures such as %BF-SKF, %BF-BIA, and WHtR may be more valid indicators of youth aerobic fitness lending to their preferred use over BMI. 1. Introduction The current pediatric obesity epidemic manifests concerns for adverse cardiovascular risk factors among overweight youth. However, Eisenmann et al. [1], using body mass index (BMI) as the marker of adiposity, found that youth in both the low- and high-BMI categories were associated with a more favorable cardiovascular disease (CVD) risk-factor profile than individuals whose BMIs were in the “healthy” range. This paradox leads to a significant issue in assessing health and fitness in youth when using BMI. Research has also suggested that along with body composition, aerobic fitness must also be considered to accurately assess health status in a population. Lee et al. [2] found that unfit lean men had a higher risk of cardiovascular disease and all-cause mortality than fit but overweight men. These findings suggest that fitness offers some protection against CVD risk even if the individual is overweight. Similar results have been reported for the female population [3]. Using skinfold thickness as the measure of body fatness and stratifying youth into high-fat/high-fitness, high-fat/low-fitness, low-fat/high-fitness, and low-fat/low-fitness groups, it was found that
Cardiorespiratory Fitness, Metabolic Risk, and Inflammation in Children  [PDF]
Antonios D. Christodoulos,Helen T. Douda,Savvas P. Tokmakidis
International Journal of Pediatrics , 2012, DOI: 10.1155/2012/270515
Abstract: The aim of this study was to investigate the independent associations among cardiorespiratory fitness, metabolic syndrome (MetS), and C-reactive protein (CRP) in children. The sample consisted of 112 children (11.4  ±  0.4 years). Data was obtained for children’s anthropometry, cardiorespiratory fitness, MetS components, and CRP levels. MetS was defined using criteria analogous to the Adult Treatment Panel III definition. A MetS risk score was also computed. Prevalence of the MetS was 5.4%, without gender differences. Subjects with low fitness showed significantly higher MetS risk (<0.001) and CRP (<0.007), compared to the high-fitness pupils. However, differences in MetS risk, and CRP between fitness groups decreased when adjusted for waist circumference. These data indicate that the mechanisms linking cardiorespiratory fitness, MetS risk and inflammation in children are extensively affected by obesity. Intervention strategies aiming at reducing obesity and improving cardiorespiratory fitness in childhood might contribute to the prevention of the MetS in adulthood.
Cardiorespiratory Fitness, Metabolic Risk, and Inflammation in Children  [PDF]
Antonios D. Christodoulos,Helen T. Douda,Savvas P. Tokmakidis
International Journal of Pediatrics , 2012, DOI: 10.1155/2012/270515
Abstract: The aim of this study was to investigate the independent associations among cardiorespiratory fitness, metabolic syndrome (MetS), and C-reactive protein (CRP) in children. The sample consisted of 112 children (11.4??±??0.4 years). Data was obtained for children’s anthropometry, cardiorespiratory fitness, MetS components, and CRP levels. MetS was defined using criteria analogous to the Adult Treatment Panel III definition. A MetS risk score was also computed. Prevalence of the MetS was 5.4%, without gender differences. Subjects with low fitness showed significantly higher MetS risk ( ) and CRP ( ), compared to the high-fitness pupils. However, differences in MetS risk, and CRP between fitness groups decreased when adjusted for waist circumference. These data indicate that the mechanisms linking cardiorespiratory fitness, MetS risk and inflammation in children are extensively affected by obesity. Intervention strategies aiming at reducing obesity and improving cardiorespiratory fitness in childhood might contribute to the prevention of the MetS in adulthood. 1. Introduction The prevalence and severity of obesity is increasing dramatically among children and adolescents in many parts of the world, whereas prevalence rates are estimated to increase in the next decades [1]. In children, excess body fat appears to be strongly associated with the clustering of risk factors, such as hyperglycemia, dyslipidemia, and hypertension, which play a key role in the pathogenesis of the metabolic syndrome (MetS) [2]. Obesity and the MetS risk in children have been recently associated with systemic inflammatory markers, in particular C-reactive protein (CRP) [3, 4], implying that low-grade inflammation can already exist in childhood and may be a potential link between the obesity and the MetS. Among behavioral variables, cardiorespiratory fitness has a protective role in MetS and inflammatory factors; however, it is not entirely clear if the interrelations among cardiorespiratory fitness, MetS risk, and inflammation in children are independent or partly due to the mediating effect of obesity, since the existing data are limited and equivocal [5, 6]. Recent evidence indicates that the prevalence rates of childhood obesity in Greece remain high [1, 7] and often coexist with low cardiorespiratory fitness [8] and an unfavorable cardiometabolic risk profile [9]. For the Greek pediatric population these data suggest an increased cardiovascular morbidity in adulthood, given that high-risk children and adolescents are likely to become high-risk adults [10]. Although the
Relationship of Body Fat and Cardiorespiratory Fitness with Cardiovascular Risk in Chinese Children  [PDF]
Pei-gang Wang,Jie Gong,Su-qing Wang,Evelyn O. Talbott,Bo Zhang,Qi-qiang He
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0027896
Abstract: Cardiorespiratory fitness (CRF) and body fat play an important role in elevated risk for cardiovascular disease (CVD). However, the combined effects of CRF and obesity on metabolic health in Chinese children are unclear. The purpose of this study was to investigate the independent and combined associations between body fat, CRF, and CVD risk in Chinese schoolchildren.
Cardiorespiratory Fitness and Attentional Control in the Aging Brain  [PDF]
Ruchika Shaurya Prakash,Michelle W. Voss,Kirk I. Erickson,Jason M. Lewis,Laura Chaddock,Edward Malkowski,Heloisa Alves,Jennifer Kim,Amanda Szabo,Siobhan M. White,Thomas R. Wójcicki,Emily L. Klamm,Edward McAuley,Arthur F. Kramer
Frontiers in Human Neuroscience , 2011, DOI: 10.3389/fnhum.2010.00229
Abstract: A growing body of literature provides evidence for the prophylactic influence of cardiorespiratory fitness on cognitive decline in older adults. This study examined the association between cardiorespiratory fitness and recruitment of the neural circuits involved in an attentional control task in a group of healthy older adults. Employing a version of the Stroop task, we examined whether higher levels of cardiorespiratory fitness were associated with an increase in activation in cortical regions responsible for imposing attentional control along with an up-regulation of activity in sensory brain regions that process task-relevant representations. Higher fitness levels were associated with better behavioral performance and an increase in the recruitment of prefrontal and parietal cortices in the most challenging condition, thus providing evidence that cardiorespiratory fitness is associated with an increase in the recruitment of the anterior processing regions. There was a top-down modulation of extrastriate visual areas that process both task-relevant and task-irrelevant attributes relative to the baseline. However, fitness was not associated with differential activation in the posterior processing regions, suggesting that fitness enhances attentional function by primarily influencing the neural circuitry of anterior cortical regions. This study provides novel evidence of a differential association of fitness with anterior and posterior brain regions, shedding further light onto the neural changes accompanying cardiorespiratory fitness.
Combined Impact of Cardiorespiratory Fitness and Visceral Adiposity on Metabolic Syndrome in Overweight and Obese Adults in Korea  [PDF]
Sue Kim, Ji-Young Kim, Duk-Chul Lee, Hye-Sun Lee, Ji-Won Lee, Justin Y. Jeon
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0085742
Abstract: Background Obesity, especially visceral obesity, is known to be an important correlate for cardiovascular disease and increased mortality. On the other hand, high cardiorespiratory fitness is suggested to be an effective contributor for reducing this risk. This study was conducted to determine the combined impact of cardiorespiratory fitness and visceral adiposity, otherwise known as fitness and fatness, on metabolic syndrome in overweight and obese adults. Methods A total of 232 overweight and obese individuals were grouped into four subtypes according to their fitness level. This was measured by recovery heart rate from a step test in addition to visceral adiposity defined as the visceral adipose tissue area to subcutaneous adipose tissue area ratio (VAT/SAT ratio). Associations of fitness and visceral fatness were analyzed in comparison with the prevalence of metabolic syndrome. Results The high visceral fat and low fitness group had the highest prevalence of metabolic syndrome [Odds Ratio (OR) 5.02; 95% Confidence Interval (CI) 1.85–13.61] compared with the reference group, which was the low visceral adiposity and high fitness group, after adjustments for confounding factors. Viscerally lean but unfit subjects were associated with a higher prevalence of metabolic syndrome than more viscerally obese but fit subjects (OR 3.42; 95% CI 1.27–9.19, and OR 2.70; 95% CI 1.01–7.25, respectively). Conclusions Our study shows that visceral obesity and fitness levels are cumulatively associated with a higher prevalence of metabolic syndrome in healthy overweight and obese adults. This suggests that cardiorespiratory fitness is a significant modifier in the relation of visceral adiposity to adverse metabolic outcomes in overweight and obese individuals.
Cardiorespiratory fitness in breast cancer survivors
David Burnett, Patricia Kluding, Charles Porter, Carol Fabian and Jennifer Klemp
SpringerPlus , 2013, DOI: 10.1186/2193-1801-2-68
Abstract: Maximal oxygen uptake (VO2max) has been used to assess risk for all-cause mortality and cardiovascular disease (CVD), and low VO2max has recently been associated with increased mortality from breast cancer. The purpose of this study was to determine the proportion of breast cancer survivors with 2 or more risk factors for CVD exhibiting a low VO2max and to determine whether sub-maximal endpoints which could be applied more readily to intervention research would correlate with the maximal treadmill test. We performed a single VO2max test on a treadmill with 30 breast cancer survivors age 30--60 (mean age 50.5 +/- 5.6 years) who had 2 or more cardiac risk factors for CVD not related to treatment and who had received systemic therapy and or left chest radiation. Submaximal VO2 endpoints were assessed during the VO2max treadmill test and on an Arc trainer. Resting left ventricular ejection fraction (LVEF) was also assessed by echocardiogram (ECHO) or multi-gated acquisition scan (MUGA). A majority (23/30) of women had a VO2max below the 20th percentile based on their predicted normal values. The group mean resting LVEF was 60.5 +/- 5.0%. Submaximal VO2 measures were strongly correlated with the maximal test including; 1) 85% age predicted maximum heart rate VO2 on treadmill, (r = .89; p < 0.001), 2) treadmill VO2 at anaerobic threshold (AT), (r = .83; p < 0.001), and 3) Arc VO2 at AT, (r = .80; p < 0.001). Breast cancer survivors with 2 or more CVD risk factors but normal LVEF had a low cardiorespiratory fitness level compared to normative values in the healthy population placing them at increased risk for breast cancer and cardiovascular mortality. Submaximal VO2 exercise testing endpoints showed a strong correlation with the VO2max test in breast cancer survivors and is a good candidate for testing interventions to improve cardiorespiratory fitness.
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