She writes children's books and makes wine, dons a spandex leotard like no one else and has sold millions of albums around the world. Now she wants you to have a toned body.

Madonna launched her new brand of "Hard Candy Fitness" gyms in Mexico City on Monday, opening a huge, 30,000-square-foot (2,787-square-meter) compound where Mexico's rich and the beautiful can go through dance classes and fitness routines inspired by the singer's routines.

So why choose a sprawling metropolis of some 20 million people, struggling with crime, pollution and endless traffic jams to kick off an international sports venture that may eventually include gyms in Russia, Brazil and Argentina?

"I have a history with Mexico," Madonna, wearing a black and white-striped dress with boots, told Reuters.

"I have a connection that I have always felt anyways because of my love and interest in Frida Kahlo," she added, referring to one of Mexico's best-known 20th century painters.

Hundreds of screaming fans, from boys wearing "Mexicans do it better" T-shirts to drag queens in leg warmers, lined up outside the gym in a fruitless effort to get a glimpse of the singer, who arrived tightly protected by security.

Guests at the launch included the capital's mayor, Marcelo Ebrard, and Carlos Slim Domit, the son of the world's richest man, Carlos Slim.

Inside the new gym, Madonna taught a short dance lesson to a handful of lucky gym members handpicked by her staff to join her on the dance floor for a few minutes.

She said she is getting ready for another busy year in 2011 that will include a new movie and an album that would follow on the steps of her highly successful "Hard Candy" studio album.

Asked whether she would pursue new collaborations as she did with stars such as Justin Timberlake, she said only that she is working with fellow artists.

On the home front, the mother of four kept open the possibility of expanding her brood.

"Who knows?" she said.