I have quite a large heart rate range to improve on – 135 now > 175 goal.
Why 175? That seems overly ambitious. What benchmark or test is leading you to think that that’s a realistic target?
My main question is how much can i safely increase…
If you’re fully recovered in 24 hours, then I think you’re on the right track.
is it fine to do this during ADS training?
Yes, no problem.
…is 10 hours of Z1 better than 7-8 hours of Z2 better for correcting ADS, assuming the distances run are the same?
When curing ADS, focus on duration and let the distance take care of itself. Distance is an important metric in a race context, but for ADS, duration is much more relevant.
Z2 will be better than Z1, but Z1 is not wasted time by any means. Overall, it’s the most important intensity.
Intuition, plus what elites under Canova do (40k at 95% marathon pace) seems to indicate that the distance is the important factor.
Comparing ADS and a Canova runner prepping for a marathon is like comparing apples and… a rare fruit on a special plant on Mars!
…just trying to learn as much as possible as I am self=coaching.
My general recommendation is to be conservative and patient. Don’t worry about squeezing every last drop of energy. Do what feels like 80% of your training potential, and do it over a long, long time. You’ll progress more consistently with that approach.
And don’t worry about Canova until you’re AnT/AeT gap is 8% or less (preferably by pace)!