Cardiopulmonary Exercise Testing (CPET) permits simultaneous evaluation of the ability of the cardiovascular and respiratory systems to perform their major function, that is, gas exchange  between the cells and the environment.

Because exercise requires an integrative cardiopulmonary response to support the increase in muscle required, gas exchange measurements are fundamental to understanding the mechanism(s) of exercise limitation.

It is evident from research that a reduction in peak VO2 (VO2max) can be caused by any disease process affecting skeletal muscle function or the organ systems to transport O2 and CO2 between the air and the muscle cell.

Use of CPET to determine only VO2 max or peak VO2, as is commonly done, fails to employ this laboratory test for its unique capability: to define pathophysiology of exercise limitation.

This blog describes measurements obtained from CPET that are useful when assessing the responses of each of the organ systems coupling external respiration (O2 uptake and CO2 output at the airway) to cellular respiration (O2 consumption and CO2 production of the cells) during exercise.