In CPET, ventilatory threshold is best described as which of the following?

• A. The onset of lactate production
• B. The point at which ventilation increases disproportionately to VO2
• C. The maximum heart rate
• D. The plateau of oxygen consumption with increasing workload

Answer: (B)

Ventilatory threshold is the point during increasing exercise where ventilation begins to rise more steeply than oxygen uptake. As work rate climbs, the body relies more on anaerobic metabolism, producing lactate. The buffering of the resulting hydrogen ions increases CO2, which drives ventilation up. This makes ventilation increase disproportionately to VO2, signaling the threshold.

So, the best description is the moment when ventilation outpaces VO2. It’s not simply when lactate first appears, nor is it the maximum heart rate, nor a plateau in oxygen consumption (that would be VO2max).