Figure 1. Defining VO₂ recovery delay.

This illustration contains data from two patients with heart failure who demonstrate distinct patterns of VO₂RD. The gray area illustrates the final portion of incremental ramp exercise. VO₂RD was defined as the duration of time from end exercise until the time when oxygen consumption (VO₂) fell permanently below peak VO₂ (dashed lines). The blue line represents a patient who has an immediate decrement in VO₂ following completion of the exercise period (shaded in gray) with a resultant VO₂RD value of 0 seconds. In contrast, the second patient’s VO₂ (red line) remained at values at or above those achieved at peak exercise for 55 seconds after exercise before beginning to decline.