The hypoxia I describe is local hypoxic conditions. I’ve taken this information from a text authored by Zhelyazkov and Dasheva (published in 2001) that is used at the NSA. I should also note that Issurin has written about this subject as well.
An example of this:
The local hypoxia is generated, for instance, during exercise which incrementally increases in demand such that the muscle contractions are not allowed a relaxation phase (ergo constant tension) and the intensity/duration surpasses the aerobic processes.
I agree that there are many interpretations of the anaerobic threshold.