Which three parameters are commonly evaluated during CPET (cardiopulmonary exercise testing)?

• A. Peak VO2, ventilatory threshold, and exercise duration
• B. Heart rate, blood pressure, and oxygen saturation
• C. VO2 max, CO2 production, and lactate threshold
• D. Respiratory rate, tidal volume, and inspiratory time

Answer: (C)

In CPET, we focus on how the body uses oxygen, how it produces and handles CO2, and where the shift from aerobic to anaerobic metabolism occurs as effort increases. The best three measures to capture this are maximal oxygen uptake (VO2 max), carbon dioxide production (VCO2), and lactate threshold. VO2 max tells us the highest amount of oxygen the body can utilize during intense exercise and is a direct indicator of aerobic capacity. VCO2 reflects the amount of CO2 produced and, together with VO2, helps assess ventilatory efficiency and the body's metabolic response throughout the increasing workload. Lactate threshold marks the exercise intensity at which lactate starts to accumulate in the blood, signaling when anaerobic metabolism begins to contribute substantially to energy production. This trio provides a clear view of oxygen delivery and use, metabolic control, and endurance potential, which is why it’s considered the core set for CPET. Other options flag individual vitals or basic breathing measurements, which are useful but don’t capture the integrated metabolic and aerobic performance as effectively.