It's easy these days to write off young actresses as being manufactured products of Hollywood.

Yet if they take a page out of the book of the likes of Angelina Jolie or Jessica Alba, they might realise that there's a lot more to navigating Hollywood than just looking pretty.

That's not to say Jolie and Alba aren't two of Hollywood's most beautiful actresses. They're just two of the smartest - and two of the fittest.

While Jolie has demonstrated her physical prowess in Tomb Raider, Wanted and Salt, Alba, who started out in television's Dark Angel and who was the sole female superhero in Fantastic Four and its sequel Rise of the Silver Surfer, is now kicking some serious ass in the Mexploitation movie, Machete, by her Sin City director, Robert Rodriguez.

In fact, now happily married to film producer Cash Warren, the 29-year-old mother of Honor, 2, is proud to have played a Mexican action heroine in her first Latina role.

"I have always been attracted to strong, powerful women, like in Aliens, Terminator, Nikita and even The Professional, Natalie Portman's character," says Alba, who was born in California to a Mexican-American father and a mother who is of French and Danish descent.