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.

Where is the ventilatory threshold?

The ventilatory (anaerobic) threshold during short-term exercise has been defined as the O2 uptake (VO2) immediately below the VO2 at which pulmonary ventilation (VE) increases disproportionally relative to VO2 and the ventilatory threshold for long-term exercise as the VO2 immediately below the VO2 at which the VE ...

Why does ventilatory threshold occur?

As the intensity level of the activity being performed increases, breathing becomes faster; more steadily first and then more rapid as the intensity increases. When breathing surpasses normal ventilation rate, one has reached ventilatory threshold.