There is a close relationship between peak exercise VO2 (horizontal axis) and proximal aortic distensibility (vertical axis) in a group of 30 subjects (10 healthy young persons, 10 healthy elderly persons, and 10 elderly patients who have DHF). Each symbol represents the data from one participant. (From Hundley WG, Kitzman DW, Morgan TM, et al. Cardiac cycle dependent changes in aortic area and aortic distensibility are reduced in older patients with isolated diastolic heart failure and correlate with exercise intolerance. J Am Coll Cardiol 2001;38(3):796-802; with permission. Copyright © 2001, American College of Cardiology.)