“Recently, Madonna’s cultural muscle has been underlined by the very visible development of her physical strength,” the Observer noted of the Queen of Pop, who has just turned 50 years old.

“She has made Ashtanga yoga the quintessential exercise du jour, and made it fashionable for a woman to look physically powerful.”

Not only does she look remarkable for a woman of half a century, but Madonna remains very much on top of her game: her current album Hard Candy is as smartly assertive as any she has ever released.

“Madonna can still scoff at wannabes half her age because she has stayed so flexible with her sound,” noted Rolling Stone magazine.

To celebrate Madonna’s birthday, Vision FILM this month has her rockumentary In Bed With Madonna, in which she reveals a level of ambition that terrifies her then-boyfriend Warren Beatty.

And Vision MUSIC has a selection of her greatest hits, including La Isla Bonita, Papa Don’t Preach and Erotica. The videos go all the way back to a much more innocent Madonna: 1985′s Like A Virgin, and 1983′s aerobics-addicted Lucky Star.

Her recent duet with Justin Timberlake on 4 Minutes, meanwhile, shows just how far she has come, and just how much she has left in her.

“Will she still be performing in her 60s?” the Observer asked.

“We shouldn’t underestimate her. Madonna might still be capable of stamping her foot and getting what she wants for years to come.”