Anaerobic Threshold (AT): What is it?

Wasserman, Hansen, Sue & Whipp state: We believe the AT to be the best determinant available to demarcate the upper limit of work rate which can be endured for a prolonged period. Thus, a task performed below the AT can be sustained. A task performed above the AT cannot be sustained as long; the higher the work rate above AT, the less is its tolerable duration.

Also: The VO2 at which blood lactate level begins to be elevated has been used to define the AT in normal subjects.

In other words, the "AT" occurs at the same time as the Lactate Threshold "LT"

Click here for above reference