Thursday, February 24, 2011

Ventilatory Threshold (VT) vs Lactate Threshold (LT) - Quick summary

Q. What is the Ventilatory Threshold, Anaerobic Threshold, and how are these different than Lactate Threshold?

A. The Ventilatory Threshold (VT) is determined from ventilatory changes that reflect a trend change in your CO2 extraction, O2 consumption, and the breathing volume and rate. This trend change is often highly correlated with the lactate threshold. Both suggest a trend toward accelerated or accumulating fatigue problems. The Anaerobic Threshold (AT) refers also to a more fatiguing, non sustainable, level of exercise intensity where your body can no longer rely on utilizing fat and oxygen to maintain energy demands. The AT is determined when the RER exceeds 1.0 which is when 100% of your energy is now coming from carbohydrates. The assumptions are that VT and AT occur at very similar levels of intensity to the Lactate Threshold (LT). The LT is when lactate production becomes greater than lactate clearance, causing a buildup of lactate in the blood. Again, we can perform blood lactate testing to find this point but this involves frequent blood sampling throughout the test, with only a fraction of data points that are obtained from ventilator testing, and no "maximum fat burning" determination. It is your threshold characteristics that are by far the most informative and important information for evaluating the training effect

No comments: