“Women feel very empowered wearing heels,” Ms. Cassetta said. “I love heels. I love the way my legs look in them. But most women can barely walk in them, let alone run. If you can’t run away, you better know how to fight off an attacker. You have to be prepared at all times, no matter what you’re wearing, no matter how tall you are.”

While it is known that shoes can be lethal weapons — last year, Ana Trujillo of Texas was sentenced to life in prison for stabbing her boyfriend to death with a 5½-inch stiletto heel — they are not always easily accessible when they are on your feet. And they tend to handicap one of the best strategies for self-defense: running away.

But despite warnings about the perils of heels, and the havoc they can wreak on backs and ankles (“Working out in heels is really bad for your calves, and can cause tears or tendinitis,” said Rob Conenello, a sports podiatrist in Orangeburg, N.Y., and the past president of the American Academy of Podiatric Sports Medicine) it’s unlikely that urban women are going to stop wearing them anytime soon. So some concerned with safety are factoring in that reality.

According to a United Nations analysis, about 35 percent of women worldwide said they had experienced physical violence, including rape, murder and sexual harassment.

Ms. Zeisler is one of them. At 19, she was sexually assaulted by her boyfriend at the time, after which she went through a debilitating depression. She left her home in Toronto and traveled to Israel, her father’s birthplace, to study Krav Maga, an Israeli form of self-defense.