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, 10 healthy old, and 10 elderly DHF patients). Each symbol represents the data from 1 participant. From Hundley WG, Kitzman DW, Morgan TM, Hamilton CA, Darty S.N., Stewart KP 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.