In Hollywood "some of" means they posed for the poster.

This is far from the first time someone has claimed to have danced/sung/did their own stunts, when actually someone else did the hard stuff..

One of the best examples of trying to appear more talented than they really were was Jennifer Beals of "Flashdance" fame.

Beals talked endlesssly about the grueling challenges faced in the movie's amazing dance scenes.   It turns out that the only dancing Beals did was when she had to dance around the press after it was revealed that not one...but TWO dance doubles did everything but the super close-ups!

In the case of "Black Swan", the actress who actually did the dancing say's that she knew she would not get much screen credit for her efforts but felt that the film's star,

, was going just a bit overboard in taking credit for doing her own dancing.

The lady making the claims is truly an accomplished ballet dancer by the name of Sarah Lane (below)

According to Lane, Natalie Portman performed about 5% of the dancing in the movie.

Portman's people are denying the claim.