Does this mean I should be able to run “easily” e.g. 2+h at my AeT?
Not necessarily. For people new to training, the gap between AeT and AnT is usually quite large. With an undeveloped (or damaged) aerobic system, AeT will be quite slow. So new athletes can do almost all of their training at AeT.
As athletes get fitter, the two thresholds converge. This usually means that AeT rises to meet AnT. It does so first by heart rate and then by pace.
Once AeT and AnT paces are relatively close together, AeT is no longer “easy”. It’ll be almost as fatiguing as AnT work. The metabolic cost is low (~2 mM), but the neuromuscular fatigue is high.
For example, I spent the first three years of my skimo training at AeT almost all of the time. By the fourth season, I just couldn’t tolerate the volume at AeT, so I had to train slower. And then much slower as my top speeds got faster. The good news is that once AeT and AnT are close, AeT training doesn’t need as much of a stimulus as it did in the beginning. Training slower will support it quite well.
If you use Training Peaks to track your training, this is where their metrics really help because they’re based off of AnT. The TP metrics are not ideal for describing fitness, but they do a pretty good job of gauging fatigue.
TP always measures fatigue based on AnT, so as AeT rises, the fatigue in Training Peaks from those workouts also rises.
Does that make sense?
P.S. Is there a lab near where you live that you could get a lactate test done? You seem serious enough about your training that I think you’d benefit from knowing exactly where your AeT is.