My rule of thumb, though I never did a running regiment, when I USED to work out (it's been a good long while though :lol)
For every week you miss, you set yourself back 2 weeks...
Now, I don't mean you lose everything, but, I mean that the full soreness returns after your workout, you don't have as much go forward push/stamina during the workout... And it normally takes a week-2 weeks to get back to where you were before you missed a week..
Now, every person is different, that is just what I noticed for myself when I would miss a full week.
Warncnutz would possible be a good person to talk to, he lives in the gym :shrug: