I think this chart may help…
If you are yellow it’s because of negative form on peak / HIE strain, not due to low strain form… so you could otherwise have been blue already, if not for the peak / hie form… so if you then have a few days off you can end up with a very positive low form (green) by the time your peak / hie recovers… (as you recover you move up and to the right of the chart)