Cardiopulmonary Exercise Testing, commonly referred to as CPET, is a specialized assessment that evaluates how efficiently the heart, lungs, blood vessels, and muscles work together during physical exertion. Unlike resting tests that provide only static measurements, CPET examines dynamic responses to exercise, allowing for an in-depth understanding of exercise tolerance, aerobic capacity, and functional health. It is particularly valuable for diagnosing unexplained fatigue, breathlessness, or exercise limitations that are not evident with standard diagnostic tools.

During CPET, individuals perform graded exercise on either a treadmill or a stationary cycle while wearing a mask connected to a metabolic analyzer. This apparatus measures oxygen consumption (VO₂), carbon dioxide production (VCO₂), ventilation, and breathing patterns in real time. Simultaneously, electrocardiography monitors heart rhythm, while blood pressure and perceived exertion are recorded. Exercise intensity gradually increases until the participant reaches voluntary exhaustion or clinical stopping criteria are met. These measurements allow clinicians to pinpoint whether limitations are cardiovascular, pulmonary, muscular, or metabolic in nature.

One of the key metrics obtained is VO₂ max, the maximum oxygen uptake during intense exercise. VO₂ max reflects aerobic fitness, cardiovascular efficiency, and the body’s ability to transport and utilize oxygen. Higher values indicate strong cardiopulmonary function, while lower values may indicate heart failure, lung disease, deconditioning, or metabolic inefficiency. Another important parameter is the ventilatory threshold, which marks the point when anaerobic metabolism begins, leading to lactate accumulation and increased breathing. Identifying this threshold helps tailor training programs, rehabilitation protocols, and safe exercise prescriptions.