Cardiopulmonary exercise test

Cardiopulmonary exercise testing (CPET or CPEX), also referred to as a VO2 (oxygen consumption) test, is a specialized type of stress test or exercise test that measures your exercise ability. It has been used extensively to study Myalgic encephalomyelitis/Chronic fatigue syndrome and is considered a potential biomarker for the syndrome.

Long COVID
In a single CPET test, Post-COVID-19 patients exhibited markedly reduced peak exercise aerobic capacity (VO2) compared to controls and impaired oxygen extraction, even in those without cardiopulmonary disease.