Methods and Results: Patients in Stage A and B HF who performed a cardiopulmonary exercise test were enrolled in the study (n=106; median age 65.0 years [interquartile range 52.8–73.0 years]). Exercise tolerance was examined by the percentage of predicted peak oxygen consumption (%V̇O2peak). The ascending aortic pressure waveform was estimated non-invasively. Aortic stiffness was assessed using the augmentation index (AIx) and reflection magnitude (RM). Multivariable regression analysis showed that AIx measured both before and after exercise was significantly associated with %V̇O2peak (β=−0.221 [P=0.049] and β=−0.342 [P=0.003], respectively). When participants were divided into %V̇O2peak subgroups using a cut-off value of 60%, RM decreased immediately after exercise and remained lower 5 min after exercise in the group with preserved exercise tolerance, but recovered to baseline levels 5 min after exercise in the group with reduced exercise tolerance.