u/sirwritestoomuch

I've been on a bit of a "get my shit together" fitness journey since I've entered my 30s.

HIIT used to be my white whale, but in the past 6 months I've made it a priority to get my VO2 up. About 6 months ago, I started doing Norwegian 4x4s twice per week, sometimes alternating the Seiler 4x8.

The first month or two was brutal, but now after month 6, I can spend 20+ minutes in Zone 5 and it's basically become an endorphin rush that I enjoy.

My question is: where do I go from here? I can't imagine I just keep spamming 4x4s and 4x8s, right?

What's my next adjustment to keep getting to Elite VO2?