Fit Madonna opens doors to her gym with a dance

"It", of course, is the toned body for which the world's best-known pop superstar is as famous as she is for her music. How she has achieved it has attracted more interest than the training schedule of the most successful Olympic athlete.

And with the opening last week of Madonna's latest venture, a gym in Mexico City, Madge's fitness routine is under the spotlight again.

As part of the Madonna empire, the Mexican enterprise is, of course, no ordinary gym. Hard Candy, named after Madonna's latest album, is - quite literally - an all-singing, all-dancing place where classes form as important a part of the set-up as the state-of-the-art equipment.

It was no surprise that the opening of the gym involved a dance class led by Madonna herself. Her status as Queen of Fitness is largely down to her obsession with dance. She prefers to be called a performance artist than a pop star and sees her dancing as an integral part of what she does.

"I think of myself primarily as a dancer," she told Larry King in a television interview. "I sort of fell into singing".

Indeed, it was dance that launched Madonna on an unsuspecting world. Having won a dance scholarship to the University of Michigan, she dropped out of college and moved to New York to make a living as a dancer. Some of her auditions required her to sing, and positive reactions to her voice - and the prospect of a more lucrative career than the hand-to-mouth existence that she was forging as a dancer - encouraged her to make the move into singing.

Right from the start of her career, Madonna was known for her punishing exercise regime. As far back as the mid-1980s there were press reports of her running and exercising for a couple of hours a day, and - years ahead of her time - travelling with a personal fitness instructor.

By the end of the 1980s, it was Madonna's taut, muscular body, displayed in ever more revealing costumes in her sell-out shows, that was the focus of press attention. Articles advised readers how to achieve her look, and they all said the same thing: hours upon hours of hard physical work. In addition to running, swimming and cycling, Madonna was known to love her StairMaster, and was always just ahead of the curve.

This wasn't just the indulgence of vanity; Madonna's concerts were an extravaganza of non-stop dance, likened by one writer to an onstage Ironman Triathlon. The gruelling regime was necessary to keep the singer in peak physical condition for her tours.

It wasn't only Madonna's physical exercise that attracted the headlines; her diet came in for scrutiny, too, as we learnt that she followed a macrobiotic diet, based on whole grains, vegetables, lean protein, beans and seeds. Of Japanese origins, the diet went some way to explaining Madonna's physique and fitted with the media's image of her as an obsessive fitness freak.

Over the years she has claimed to enjoy the odd indulgence; she told Larry King that toast with strawberry jam was her favourite treat, and she admitted to Elle that she had a weakness for Cadbury Creme Eggs, but no one was left in much doubt that these were occasional, once-in-a-blue-moon exceptions. There were reports that she filled in a weekly chart with her weight, body fat percentage and calories consumed. Whatever the truth of it, her appearance spoke for itself.

Throughout the 1990s, Madonna worked with fitness trainer Ray Kabartas to hone her physique. As the millennium approached, the Material Girl's exercise regime took a more spiritual turn as she threw her energies into yoga.

Typically, the type of yoga embraced by the star was ashtanga - the most athletic form of the discipline. It is said to produce internal heat through synchronising movement with breathing while practising a set sequence of postures. Madonna took to it with her customary passion and was soon practising it for several hours every morning. She has remained a devotee to this day.

Around the same time, Pilates broke on to the fitness scene as a reaction to the bulked-up, gym-based regimes that had dominated the previous decade. Not surprisingly, Madonna led the charge. She also dabbled in callanetics (a series of tiny movements designed to tighten the body and devised, no doubt appealingly to Madonna, by a former ballerina) and gyrotonics (involving a wooden contraption of levers and pulleys believed to elongate the muscles).

These less cardio-based exercises were not a sign that Madonna was slowing down as she entered her 40s. As the decade progressed, her routine became more, rather than less, intense. Despite setbacks - she broke several bones in a fall from a horse and underwent a hernia operation - Madonna's fitness regime was stepped up with the arrival in her life of the fitness guru Tracy Anderson. Herself a former dancer, Anderson promised she could deliver her clients a "teeny tiny dancer's body".

Before long, Madonna was taking part in two-hour daily sessions of dance-based cardio and weights, often in the company of her friend, the actress Gwyneth Paltrow. Anderson claimed to dislike the muscular bodies produced by heavy weights, insisting instead on multiple repetitions with light weights, but the increasingly sinewy look of Madonna's body wasn't to everyone's taste. Pictures of the star looking gaunt and thin, with protruding muscles and bulging veins, led many to feel that she'd taken it too far.

Anderson and Madonna eventually parted company, but despite going it alone there's no sign that Madge is ready to hang up her leotard. At the opening of Hard Candy she confirmed she was recording a new album which, no doubt, will be accompanied by more dance routines. She has also been linked with a new trainer, Sadie Lincoln, whose fitness method, Barre3, has its roots in dance. Madonna may be 52, but she's still hitting the dance floor.