Trial Information

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.