Ventilatory threshold

In kinesiology, the ventilatory threshold (VT1) refers to the point during exercise at which the volume of air breathed out (expiratory ventilation) starts to increase at an exponentially greater rate than VO2 (breath-by-breath volume of oxygen (O2)). VT1 is thought to reflect a person's anaerobic threshold — the point at which the oxygen supplied to the muscles no longer meets its oxygen requirements at a given work rate — and therefore lactate threshold — the point at which lactate begins to accumulate in the blood, because with ongoing dependence on anaerobic glycolysis, increasing amounts of CO2 need to be exhaled to accommodate its production during the conversion of lactic acid to lactate.

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. For most people this threshold lies at exercise intensities between 50% and 75% of VO2 max. A major factor affecting one's ventilatory threshold is their maximal ventilation (amount of air entering and exiting lungs). This is dependent on their personal experience with the activity and how physically fit the person is. Comparison studies of more athletic people have shown that your ventilatory threshold occurs at a higher intensity if you are more active or have been training for that exercise; although, in some cases shorter continuous tests can be used because of rapid alterations in ventilation.

Methods

Ventilation Curve – Plot VE vs. VO2 or Watts or Time – The point at which there is a non‐linear increase in ventilation

V‐Slope Method – Plot VO2 vs.