There’s a really good discussion on this in this thread: Catch 22 on VO2 work - #73 by RobertSims
Essentially, Chad says he sometimes does a ‘Vo2Max bootcamp’ before a base phase, which helps improve that system. He says that even as short as a 1-2 week focus on VO2Max can see enormous improvements.
I’ve been trying to start this for a few weeks now, but thanks to a hectic race schedule, I’ve not had the available training time. But, my first set in this regime starts tonight!
The TL;DR is to do a short manual plan along the lines of:
An example would be something like this: Gendarme or Taylor -2, Stanislaus -4, Freel +1, Bashful, Baird +2, Mills or Gawler, Dade +1, then finally something awful like Spencer.
I’d add in a few days of rest, or something like Lazy Mountain to assist recovery.