Law of diminishing returns

You will see bigger gains at the beginning of a new training cycle/process.

The longer you have been working out/running the more you will hard to do to see improvements

Improvement in form/mental training/pacing

There are multiple ways someone can improve. Simply improving your pacing to give you faster times immediately without any additional fitness being gained

How long do you see improved VO2MAX actual physical gains?

6 weeks

You can start losing them at 2 weeks

It’s easier to gain back fitness than it is to get fit in the first place