Over 40 and still sexy? Take a number.

Women like Demi Moore, Heather Locklear, Shania Twain, and the women on Desperate Housewives are already showing us how it’s done. They’re dressing like younger women, dating younger men, and holding their own in steamy on-screen love scenes.

What they’re not doing, however, is heading up two-hour dance extravaganzas every night for weeks on end, year after year after year. That honor belongs to Madonna, who is gearing up to do it all over again on her Confessions tour, scheduled to launch May 21. Never mind that she’s 47 and the mother of two young children.

Many working mothers of Madonna’s age count themselves lucky if they can steal away to the gym for a few days a week. Meanwhile, Madonna is reportedly learning to “krump.” Featured by dancers on her recent videos, krumping is an aggressive hip-hop style so speedy it seems almost superhuman. The tabloids report she’s working upwards of 13 hours a day to perfect her routines.

Without ever speaking a word on the subject, Madonna may have done more to spur the world’s collective fitness than anyone else. Her bouncy singles have been the backdrop for an untold number of aerobics classes and treadmill sessions, not to mention dance-floor workouts. But when it comes to fitness and health, is Madonna a role model for the rest of us, or is she a celebrity freak?

The answer, it appears, is both. Few in the world may have both the genetic makeup and fame-given wealth required to look like Madonna does at 47. But health experts note that Madonna wouldn’t still be going so strong if she wasn’t seriously devoted to her healthy habits. And that devotion is part of why she’s aged so well -- and is likely to continue aging well in the years to come.

The Daily Grind

Madonna celebrated her 47th birthday last August by taking a horseback ride through the British countryside -- and then taking a nasty fall, breaking her ribs, collarbone, and hand. But the accident barely slowed her down.

Madonna Breaks Bones in Fall From Horse

She stopped doing yoga to let her shoulder heal but replaced it with more Pilates and ballet-oriented workouts. She shot the video for “Hung Up,” the first video for her new album, while her bones were still healing.

“Pharmaceuticals and my will got me through the shoot,” she said in a recent issue of Harper’s Bazaar magazine.

Madonna’s resilience speaks to a lifetime obsession with fitness. (After all, this is a woman who had her first child with a former physical trainer, Carlos Leon.) She is credited with popularizing the vigorous Ashtanga style of yoga. And her devotion to Pilates is also well known.

Madonna has also spoken about her macrobiotic diet. In an interview with CNN’s Larry King she described her typical dinner as “fish, some kind of grains, some kind of cooked vegetable, [and] salad. Simple, but tasty.” And for dessert? “When I’m sneaking and I’m having a moment of decadence, I eat toast with strawberry jam,” she told King.

The macrobiotic diet is derived from Japanese traditions. Last year, Madonna told a group of Japanese journalists that she has “a Japanese chef in London that travels everywhere with me. I probably eat more Japanese food than you do.”

More detailed accounts of Madonna’s health habits are hard to come by, except through accounts in tabloids. The Daily Mail in Britain reports that Madonna works out at least three hours a day. Here’s how the paper described a typical workout:

She starts with yoga at a home gym. She moves on to a North London Pilates studio (where she is occasionally joined by Gwyneth Paltrow and Stella McCartney). For a third session after lunch, she chooses from a variety of options including karate, swimming, weightlifting, running, cycling, and occasionally horse riding.

The Daily Mail claims she also uses a StairMaster in her office as she takes calls. She supposedly maintained a 45-minute-a-day StairMaster regime until the day before giving birth to her first child, Lourdes.

Madonna’s workout tastes can also run to the more exotic. She reportedly uses a complex device called a Gyrotonic Expansion System that is said to stretch and tone smaller muscles. In the wake of her equestrian accident, she also reportedly bought a Power Plate, a vibrating platform alleged to help bone density and fight osteoporosis, according to the Power Plate web site.

Sound like a tiring lifestyle to you? She supposedly kicks it up a notch as tours approach. Celebrity magazine U.S. Weekly claims that doctors advised her to limit rehearsals to a few hours each day after her accident, but that she’s ignored that advice in favor of exhausting 14-hour days. Madonna’s publicist did not respond to requests for comment from WebMD.

Madonna is famously a lapsed Catholic, and more recently she has taken up the ancient Jewish mystical practice of Kabbalah. But there’s evidence she sees physical fitness as a route to spiritual awareness. One of her former trainers, Ray Kybartas, wrote a book Fitness is Religion: Keep the Faith in 1998. Kybartas once said that when Madonna called him to confirm her workouts, she’d ask, “What time’s church?” (Kybartas declined to comment to WebMD.)

While having a lifelong commitment to health and fitness may be commendable, the question arises: With the normal effects of aging, how long can she keep that famous body? We posed the question to a few experts.

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Keeping the Faith

It’s not something Madonna might like to admit, but at 47, her physical peak is clearly behind her.

Maximum oxygen consumption peaks in the early 20s, Barbara Bushman, professor of health and physical education at Missouri State University, tells WebMD. So to achieve the same fitness results as she did in her “Material Girl” era, Madonna will have to work harder. Muscle and bone mass are also on the decline at that age.

And with the arrival of menopause -- typically in the early 50s -- bone loss will accelerate, as will her propensity to gain weight.

The good news -- for Madonna, at least -- is that her lifestyle is likely to slow the aging process.

“At this age, you get a widening of the field, as it were,” James Pawelczyk, an associate professor of physiology at Penn State University, tells WebMD. “People who have been taking care of themselves are relatively insulated from those [aging] changes compared with those who haven’t.”

Her exercise and diet both play a role. By mixing cardiovascular activity, strength training, and flexibility exercises, Madonna has minimized her risk of heart disease, preserved her bone density, and likely reduced her risk of breast cancer, Bushman says.

And what about that diet? Extremely restrictive macrobiotic regimens were once blamed for diseases like scurvy, anemia, and kidney failure. But more popular versions of the diet now allow fish, beans, nuts, and other protein sources. Today’s macrobiotic diet somewhat mirrors federal dietary guidelines, says Kristine Clark, director of sports nutrition at Penn State. It’s the sort of diet that could prevent and even treat age-related disease.

Keeping Up With Madonna – and the Joneses

Only someone like Madonna can afford the Madonna lifestyle. Her personal staff of nannies, chefs, trainers, and nutritionists ensures that her fitness never has to take a back seat to cooking, cleaning, or childrearing. And of course there’s the plastic surgery option.

But that doesn’t mean we can’t learn something from Madonna’s example. Experts say fitness should be a lifelong pursuit, and Madonna has stayed in top performing shape longer than many dancers and professional athletes.

The tabloids suggest her fitness devotion is freakish, and rumors are swirling that she’s exhausting herself to prepare for her new tour. But her excellent performance over the years suggests she’s been doing something right, Bushman says.

“My guess is she’s maintained a balance, or problems would’ve started to come up,” she says.

One source of that balance may be her obsessive cross-training. By mixing and matching activities, she increases her overall fitness and reduces the potential for injury from overuse.

Maybe you don’t have the time or the stamina to run, dance, and do yoga all in one day like Madonna. But stretch out those activities over a week and you’ve got the foundation of a good workout plan, suggests Lauren Muney, a fitness coach based in Laurel, Md.

Despite Madonna’s advantages, her commitment to healthy living well into motherhood and midlife has been an inspiration for many women.

“Madonna is kind of ageless,” says Candas Jones, 43, a third grade teacher from Lawrenceville, Ga. “No one can really put her in a category.”

Like Madonna, Jones had a child after 40 -- twins, actually, now aged 2. And like Madonna, Jones has remained fit in motherhood. But without nannies at hand, Jones and her husband, Roy, have found ways to take the children along on their workouts, whether it was in backpacks or in strollers.

Now the Joneses have built a gym in the basement that’s stocked with active toys for the kids as well as workout equipment for themselves. It even has a sound system. Guess what they listen to while working out?

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By Richard Sine, reviewed by Louise Chang, MD

SOURCES: “Why Is Madonna Punishing Herself?” Richard Price, The Daily Mail, Jan. 21, 2006. “Why Guy’s worried,” U.S. Weekly, April 24, 2006. “True Believer,” Bonnie Siegler, American Fitness, March 1998. “How to get a body like…Madonna,” Christine Morgan, The Mirror, Feb. 13, 2006. Larry King, interview with Madonna, Oct. 10, 2002 (transcript). “Madonna tells magazine she’s ‘strong again’ after last year’s horse riding accident,” Associated Press, Feb. 27, 2006. Lauren Muney, wellness and fitness coach, Laurel, Md. Barbara Bushman, PhD, professor, department of health, Missouri State University; and associate dean, graduate college, Missouri State University. Kristine Clark, PhD, director of sports nutrition, Pennsylvania State University. James Pawelczyk, PhD, associate professor of physiology, kinesiology and medicine, Pennsylvania State University. Candas Jones, Lawrenceville, Ga. Power Plate web site.