@Dada I think you might be right; I might be training too close to the top of zone 2 and bleeding into zone 3. I recently did a gas exchange test and my AeT came back at 141bpm. I’m trying to stay around 130-135bpm now (some of those runs have average HRs of ~145).
Nope, no major changes from run 24-26 (that sudden change in performance is what prompted this post). I did in fact test for covid a couple times but came back negative.
My AnT (top of zone 4?) was measured at 179bpm in that same test.