One point, called the “crossover” point, or the first ventilatory threshold (VT1), represents a level of intensity blood lactate accumulates faster than it can be cleared, which causes the person to breathe faster in an effort to blow off the extra CO2 produced by the buffering of acid metabolites.

What is ventilatory threshold and why is it important?

VT1 is called the first ventilatory threshold. It is a marker of intensity that can be observed in a person's breathing at a point where lactate begins to accumulate in the blood. As the intensity of the exercise begins to increase, VT1 can be identified at the point where the breathing rate begins to increase.

Why is anaerobic threshold important?

The anaerobic threshold (AT) is the exertion level between aerobic and anaerobic training. The AT is the point during exercise when your body must switch from aerobic to anaerobic metabolism. The AT is a useful measure for deciding exercise intensity for training and racing in endurance sports.