Clinical interpretation of cardiopulmonary exercise testing in cystic fibrosis and implications for exercise counselling.

The measurement of exercise capacity in persons with cystic fibrosis by Cardiopulmonary Exercise Testing (CPET) offers a functional assessment of lung performance and efficiency in a dynamic setting. Exercise performance can measured against predicted values and the mechanism by which exercise limitation occurs can be identified. In healthy subjects, exercise is limited by cardiac output, such that a significant breathing reserve exists at the end of exercise. However, other mechanisms of exercise limitation which may be identified in CF subjects include ventilatory limitation, and/or limitation due to physical deconditioning. A detailed understanding of exercise capacity and the mechanism for exercise limitation may enable health professionals to tailor an individualised exercise programme for each CF patient.