Jessica Alba has been doing extensive dancing to get in shape for her return to her stripper role in “Sin City: A Dame To Kill For.”

Choreographer Jennifer “JJ Dancer” Johnson told People how she worked with Jessica on her moves as Nancy Callahan, the stripper she first played in 2005’s “Sin City.”

JJ explained, “We just started moving to the music and we got her used to the sensuality and to moving in high heels at first. Then we started developing choreography for her body. She brought songs, I brought songs – some were rocky, some were sad, some were edgy, but they were all sexy.”

The dance lessons lasted between two and five hours, and Jennifer continued, “She just followed my body. I made her twist, circle and move. We held on to the wall, I made her crawl, arch and thrust. It got really hard in there.”

“She was only wearing high heels – she was wearing clothes that showed off her body and made her feel sexy. We went there!”

The dance instructor also added that a healthy diet was crucial to Jessica’s appearance for the role.

She said: “The secret to having a great body and not having to kill yourself to look good is eating right. That’s one of Jess’s strengths. She is nutritionally motivated and eats a balanced diet of salads and protein.

“If you eat right, that’s more than half the battle.”

Photo: Press Association