As fitness instructors go, the blonde in black at a gym in Mexico City’s upscale Bosques de las Lomas neighborhood last Monday was about as fit as you’ll find anywhere.

Yep, the Material Girl herself led a 20-minute dance class after cutting the ribbon at her “Virgin” Hard Candy Fitness center in Mexico City. It’s the first of a whole chain the 52-year-old pop icon plans to unveil.

And while she won’t likely be teaching any more classes, her face and her tastes are everywhere in the 30,000-square-foot gym.

According to Chris Dedicik, her partner in the gym, Madonna weighed in on everything from the weight machines to the lighting to the choreography.

The diva says she chose Mexico City to launch her new fitness empire because she liked the energy of the people she met there on last year’s Sticky & Sweet tour.

“Our plan is to use Mexico as a place to fine-tune our brand and then expand it to other countries,” she said.