- Those with pre-existing history (by self report in Group B and review of medical records in addition to self-report for Groups A & C) of abnormal cardiovascular function including: congenital heart disease, hypertension, diabetes, hypercholesterolemia on treatment, a body mass index >35, history of asymptomatic cardiac dysfunction (defined as an ejection fraction < 40 and/or shortening fraction < 28) or symptomatic cardiac dysfunction (congestive heart failure), stroke, renal dysfunction by history/medical records (serum creatinine >1.4), anemia, obstructive or restrictive airways disease