We need a doctor here! It's a really interesting subject.

I am sure that I am stronger on the bike after 6 months off than I was when I first started riding. It's all so subjective though, and I am a huge believer in mind over matter - so I know that I have done such and such ride or hill or whatever so I know I can do it again now - even if I'm out of shape. Mental memory (or maybe it's stubbornness) is almost as important, I think.