CARDIA Ancillary: 20 Year Changes in Fitness & Cardiovascular Disease Risk (CARDIA Fitness FC)

Primary Aims: 1. Determine the change in cardiovascular disease risk factors, including fasting insulin, glucose, lipids (triglycerides, HDL cholesterol), and blood pressure, over the 20 year follow-up associated with baseline level of and change in aerobic capacity; We hypothesize that lower aerobic capacity at any time and decreased aerobic capacity over time will be associated with more adverse changes in cardiovascular risk factors over the 20 year follow-up. Further, we hypothesize that: a) the inverse longitudinal relations between aerobic capacity and change in cardiovascular risk factors will still be significant after accounting for initial levels of Body Mass Index (BMI) but attenuated by increases in BMI; b) aerobic capacity will account for most of the cross-sectional and longitudinal relations between physical activity and cardiovascular disease risk; and c) aerobic capacity will reduce the level of cardiovascular risk factors associated with specific genetic variants, such as the e4 allele of the apolipoprotein E gene or the TT genotype of the hepatic lipase (LIPC) -480C>T polymorphism. 2. Determine the risk of incident hypertension, metabolic syndrome, type 2 diabetes, and subclinical cardiovascular disease (e.g. atherosclerosis, assessed by coronary artery calcium at years 15 and 20 and by carotid intimal media thickness at year 20) associated with initial level of and change in cardiorespiratory fitness; We hypothesize that the risks of these outcomes will be greater both in those who have a larger decline in aerobic capacity over time and in those who have initially low aerobic capacity that remains low relative to those who improve or maintain a higher aerobic capacity. In addition, as with the cardiovascular disease risk factors, we hypothesize that: a) these relations will still be significant after accounting for initial levels of BMI but attenuated by increases in BMI; b) aerobic capacity will account for most of the prospective relations between physical activity and cardiovascular disease outcomes; and c) aerobic capacity will reduce the risk of cardiovascular disease associated with specific genetic variant. Secondary aims are to: 1. Quantify the age-related decline in aerobic capacity over a 20-year time period from young adulthood to mid-life and examine effect modification of the rate of decline by physical activity, body fat and fat distribution and specific genetic polymorphisms, stratifying by race and gender. Secondary effect modifiers of interest include smoking and dietary factors; and 2. Compare the correlation between aerobic capacity and physical activity measured by self-report with the correlation between aerobic capacity and physical activity measured by accelerometery, stratifying by race and gender;

PI: Beth Lewis, MD MSPH