...that similar epic Nordmarka/Sognsvann runs (3 hrs+) every few weeks could be a good substitute for BCL?
My legs don't feel springy the day after a 3hour run in Nordmarka. I think it's the effect the latitude has on my tendons.
Based on my tendons I would say you got it wrong, It is longitude.
...or possibly a little bit of altitude...
I'm not sure what you guys are going on about but I just ran for 95 minutes in Nordmarka and it almost killed me, so clearly there's something different about Tucson. I stand by my latitude hypothesis.
I'm still going for attitude.