Measurement of oxygen consumption on-kinetics during exercise: implications for patients with heart failure.

Oxygen consumption (VO(2)) on-kinetics describes the rate change in oxygen uptake at the initiation of exercise. Several mathematical and graphical methods are used to assess VO(2) on-kinetics during constant-load or progressive exercise. VO(2) on-kinetics is prolonged in patients with heart failure (HF) compared with individuals who have normal cardiopulmonary function. Cardiac function has been implicated as one of the controlling mechanism for this observation. The contribution that pulmonary, vascular, and skeletal muscle function makes to delayed VO(2) on-kinetics in HF has yet to be determined. VO(2) on-kinetics also appears to have clinical value in HF, although evidence supporting this claim is limited. Questions about the controlling mechanism(s) and practical application of VO(2) on-kinetics in HF therefore remain unanswered. This report provides an overview of VO(2) on-kinetics assessment techniques, reviews research pertaining to the HF population, and provides direction for future investigations.