Effect of Exercise and Weight Loss on Cardiovascular Health

Current estimates indicate that in excess of 65 percent of adults in the United States are overweight (BMI \>25.0 kg/m2) with at least 30 percent of adults classified as obese (BMI \>30 kg/m2). Overweight and obesity have been linked to numerous chronic conditions including cardiovascular disease. The application of cardiac MRI (CMRI) allows for direct measurement of the cardiac structure, and left ventricular mass (LVM) assessed by CMRI has been shown to be predictive of cardiovascular disease. Recent studies have shown that LVM is decreased with weight loss; however, there is a lack of information on the added benefit of physical activity to weight loss on these direct measures of cardiovascular structure and function. Thus, consistent with PA-09-243, this study will examine the effect of two recommended doses of physical activity combined with a dietary intervention on changes in the proposed outcomes of cardiovascular disease risk in overweight adults. The primary aim of this study is to examine the effect of the consensus public health recommended level of physical activity \[moderate physical activity (MOD-PA) = 150 min/wk\] versus a higher dose of physical activity \[high physical activity (HIGH-PA) = 250 min/wk\] in the context of a comprehensive behavioral weight loss program that a includes a reduction in energy intake measures of cardiovascular function using cardiac MRI and biomarkers of vascular disease risk. Each of these exercise doses will be compared independently to a Diet Only group intervention on the proposed primary and secondary outcomes, with MOD-PA also compared to HIGH-PA. This study involves the recruitment of 390 overweight and obese adults who will be randomly assigned to one of the above conditions (Diet Only, MOD-PA, HIGH-PA) for a period of 12 months. The primary outcome is LVM measured by cardiac MRI. Secondary outcomes include additional cardiac MRI measures (aortic pulse wave velocity, end diastolic volume, aortic distensibility), inflammatory markers (CRP and TNFα) and selected adipocytokines (adiponectin) as biomarkers of risk related to vascular outcomes, body weight, body composition, and cardiorespiratory fitness, and traditional CVD risk factors (lipids, glucose, insulin, blood pressure). Additional secondary analyses will allow for examination of the effects of physical activity independent of weight change on the primary and secondary outcomes.