I'm not and have never been a ballet dancer, but I've been doing some research into ballet after being exposed to it in fiction. It's been fun learning about a world outside my own.

I was wondering: how long would it take a professional ballerina who's been out of practice for years to get back in shape--that is, good enough to dance as part of a major production company again? (This was something that came up in said fiction.)

Ignoring other factors like age and competing for spots in a company. I'm just curious how much effort it would take to re-obtain that level of physical aptitude, since it takes so much training to get there to begin with. How much time would already having those years of experience shave off?