High heels may boost a woman's confidence or make her feel more attractive or powerful, but they definitely don't have any positive long term effects on her body, according to a new study published in The International Journal of Clinical Practice.

Researchers at the Hanseo University in South Korea chose 10 women from each year of the flight attendant program at a Korean university to participate in the study. Because the women are required to wear 10 centimeter (almost 4 inches) high heels to class at least three times a week for all four years of the program—which helps them prepare for shoes they're required to wear as flight attendants—the researchers could compare the balance and ankle strength of the participants from each stage of the program. 

To see the effects of wearing heels, the researchers asked all 40 women to balance on a wobbly board and test their muscle strength through a computerized exercise machine. Rather than showing a steady decrease or increase in strength and balance from year one to year four, the sophomores and juniors actually had more powerful muscles around their ankles than their freshmen and senior peers. In fact, seniors had the weakest muscles and sophomores, juniors, and seniors had worse balance than freshmen.

According to the leader of the study, Dr. Jee Yong-Seok, “wearing high heeled shoes may at first lead to adaptation and increased strength,” making the muscles on the sides of the ankles grow stronger. But over time, they become disproportionate in strength to the front and back muscles, leading to an overall decrease in strength.

Even sitting in heels is bad for you: They "can alter the resting length of the muscles and tendons around the ankle," Dr. Neil Cronin, a biology professor from the University of Jyvaskyla in Finland, told The New York Times

There are a number of other studies about the effects of high heels—both on how they affect women's bodies and how they impact behavior. A study published in May from the University of Alabama at Birmingham showed that the rate of high-heel related injuries has doubled between 2002 and 2012. Another found that women who frequently wear heels have shortened calf muscles and a thicker Achilles tendon. However, unfortunately, a 2014 study showed that men are more helpful to women in heels than women in flats. 

[h/t The New York Times]