The difference between sultry stilettos and frumpy pumps is three-fourths of an inch, says Victor Chu, a former shoe designer who has developed a cottage industry for himself -- and perhaps increased the libidos of thousands of men -- by training women to walk properly and painlessly in high heels.

Chu says high heels and happy feet are not an oxymoron, if only women hold themselves correctly while walking. Recently he gave a lesson on the art of seductive walking.

"Unsexy shoes are anything under 2.75 inches," he said. "A 2-inch heel is a little dowdy -- too classical."

Plenty of people could benefit from lessons -- everyone from the fictional Carrie Bradshaw, who took a famously embarrassing catwalk spill on TV's "Sex and the City," to the real-life runway models for Pucci, Prada and Dolce & Gabbana who fell during Milan Fashion Week last year, and even Miss U.S.A., Crystal Stewart, who took a tumble at the Miss Universe pageant in July -- as did her predecessor in 2007.

Chu hasn't walked a mile in another woman's Manolos, but his experience designing sport and dress shoes as a consultant for the Tommy Hilfiger label from 2000 to 2004 gave him a different perspective. He decided he had a calling to share his know-how while chatting with a colleague, Ce Ce Chin, who has her own line called 80%20 shoes. As they sat on a park bench in New York, the conversation turned to wondering why every woman they knew had a problem walking in high heels.

"There's only so much you can do to a shoe's heel to make it comfortable, before you make it unsexy," Chu recalled saying. "Then we said, 'Wait! How do the Rockettes do it?'"

A friend of theirs danced for the Rockettes. She told them the key to wearing high heels is in walking mechanics.

Most women incorrectly shuffle their feet, placing their weight on the ball of the foot and throwing their bodies off-balance, Chu learned.

It sounds simple, he says, but the three keys to wearing high heels successfully are to stand up straight, keep your abdominal muscles taut and walk heel to toe with a slightly exaggerated hip sway.

Basically, it comes down to working your core -- as Pilates, yoga and plank exercises do. To that end, Chu and Chin developed a video called "Legworks" ($15; www.legworkdvd.com), a 28-minute exercise program to limber and stretch your ankles, calves and thighs, as well as strengthen your abdominal muscles to make it easier to maintain balance and posture while walking in high heels.

That's not to say that it's a good idea to exercise in high heels. Chu recommends against it, even though there are Crunch gyms in New York that began offering "Stiletto Strength" classes in 2006, and other gyms that offer classes in jazz, burlesque and pole dancing to women wearing high heels. Stiletto sprint foot races have even been held in Australia and New York in recent years.

The ever-increasing heel height, along with the high pitch that pushes the arch forward, is making stiletto strutting trickier than ever. The platform trend ameliorated some of the difficulty -- a 4-inch shoe is really only a 3-inch heel on a 1-inch platform.

"Swaying transfers energy from the heel to the hip," Chu says. "A lot of women think they know how to walk in high heels. But they have wobbly ankles and stiff knees from pitching forward, or they have a sort of escalator-like look from leaning backward too much, in overcompensating."