Thanks for the very helpful reply Scott. Fascinating stuff about human hearts not being the optimal size for quadrepal locomotion.
You may be onto something with acclimatisation. On short trips it when there is good weather at the start it is super tempting to do the minimum acclimatisation then get onto the main event whilst the weather holds. Something for me to think about.
Sounds like a continued focus on largely aneorobic leg work is the way forward. This is welcome advice: running and walking in the hills, with friends or alone, is a great source of joy to me, as much about living well as it is about training (although it is that too). As a follow up, how does the “AeT within 10% of AnT” calculation work on HR ( without a lab)? I am guessing this is 10% of AnT HR. So someone with a AnT of 160 would want to push their AeT to 144 (within 10%, 16 beats, of AnT) before doing much AnT work?
As to encountering overhanging ground as these altitudes: on my climbs I would regard that as a failure of my route finding skills!
Thanks for all the advice
Malcolm