Exercise and Postprandial Endothelial Function in Youth ACSM Foundation Doctoral Student Research Grant Exercise and Postprandial Endothelial Function in Youth A. Specific Aims: Pediatric obesity represents one of the most significant public health challenges facing our society. Obese youth, particularly those at the higher end of the BMI spectrum (i.e. those above the 97th percentile) are at increased risk for developing cardiovascular disease (CVD) and type 2 diabetes (T2D).(2,39) Up to 30% of obese youth> 97th percentile exhibit the metabolic syndrome which tracks into adulthood and predicts the development of CVD and T2D.(6,30,37) This is further exacerbated by the fact that adolescents> 97th percentile are the only growing population of obese youth(33), making this population of youth an optimal target for intervention. In addition to obesity, declines in physical activity levels are thought to contribute independently to increased chronic disease risk.(43,44) The Exercise is MedicineTM campaign, supported by the (ACSM), necessitates that more effective exercise prescriptions are necessary to improve the health and reduce long-term disease risk among obese youth. Moreover, exercise prescriptions for obese youth should lead to clinically measurable improvements in health indicators. A major challenge to addressing cardiovascular health in youth is the long latent period between elevated cardiovascular risk and future cardiovascular outcomes. Although the atherosclerotic process begins in childhood, for the most part it remains subclinical for a number of years.(32) Impaired endothelial function (i.e. endothelial dysfunction) is one of the earliest manifestations of atherosclerosis, (7) and non-invasive imaging techniques provide an avenue to assess this subclinical process in younger populations.(47) Several studies suggest that obesity is associated with endothelial dysfunction in youth, but very few studies have evaluated whether endothelial dysfunction can be reversed via exercise in this population.(1,28,53) The few studies to date which have utilized exercise as medicine for endothelial dysfunction have focused exclusively on endothelial function under fasting conditions.(26,51) Although most recommendations for assessment of cardiovascular risk factors, including endothelial function, call for testing to occur after a prolonged fast,(25,42) this state may not reflect the true physiologic nature of the vascular system in relation to health and disease.(23) Humans spend most of their waking time in the postprandial state, and postprandial dysregulation of carbohydrate and fat are critical pathophysiologic processes underlying CVD and T2D.(9,45) Moreover, it is clear that regular physical activity is cardioprotective, but the greatest benefit of exercise on cardiometabolic health may be observed during the postprandial state due to endothelial adaptation.(18,19) Evidence in adults suggests that exercise attenuates postprandial lipemia (22) and improves endothelial function.(16) However, the majority of these studies use continuous exercise at a moderate intensity (i.e. traditional exercise) as the exercise prescription. Recent evidence suggests that high-intensity exercise is more beneficial in improving markers of CVD, including endothelial function, in adults than a traditional clinical approach.(15) These data are accompanied by evidence that high-intensity exercise completely ameliorates high-fat meal induced postprandial endothelial dysfunction.(46) Nevertheless, despite the increasing literature to support intensity-dependent benefits of exercise on cardiovascular outcomes,(41) very few studies incorporate high-intensity exercise in youth.(21) In order to respond to the growing epidemic of obesity in youth, translational research on the effects of exercise on cardiovascular health is needed. Compiling this evidence using defined protocols and proximal indicators of vascular health is an essential step towards developing exercise prescriptions for disease prevention approaches. Therefore, the overall goal of this proposal is to examine the potential for high-intensity exercise to improve postprandial endothelial function in obese youth.
|Effective start/end date||7/1/13 → 6/30/14|
- American College of Sports Medicine: $3,860.00
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