Study: The Pain of High Heels, Explained at Last

(July 15) -- High heels can be elegant, bold or gaudy statements of a personal fashion ethic. They can also be a severe source of discomfort, especially for the many women who wear them on a regular basis, then kick them off at the end of the day and exchange them for easy, flat-soled sandals. Even Carrie Bradshaw suffered in her Manolos.

While it might be a leap to say that scientists have been desperately trying to unravel the mystery of the pain of shoe-to-shoe transition, a team of European researchers has now addressed the problem. The group, led by Robert Csapo of the University of Vienna, has come up with a detailed physiological picture of the profound changes that high heels cause in women's muscles.

When AOL News reached Csapo in his office, there was some initial miscommunication, and he declared that he was not, in fact, wearing heels himself. "I'm wearing flat shoes," he said. With that clarified, he went on to explain the findings of the study, just published in the Journal of Experimental Biology.

The work began when Csapo and his colleagues culled a group of 80 habitual high heel wearers down to 11 willing participants, then brought on another nine women who typically walked in flats.

Since high heels push the heels up closer to the knees, the intervening calf muscles are contracted, then held in a compacted position for the length of the day. Csapo and his team believed that for habitual high heel wearers, locking the calf muscles in this position probably led to a shortening of the actual muscle fibers. He figured this would also have functional consequences -- in other words, the muscles might not work as well.

The group subjected each of the women to a variety of calf- and foot-related strength tests, using MRI scans to study the length of the muscle fibers and an ultrasound-based device to assess the stiffness of particular tendons. Some of the findings were expected, others a surprise.

"The muscles in the calf muscle group were shortened in women chronically wearing high heels," Csapo said, which did match the scientists' hypothesis. But they also found that the Achilles' tendons in these women were far more stiff, and that there appeared to be little change in how well the muscles worked. "To our surprise, we did not find any differences in the functional performance."

Typically, shorter muscle fibers should produce less power, but in this case there was no difference. Csapo guessed that the stiffer Achilles tendon might have compensated for the changes in the muscle fibers.

The downside of these changes is that they probably reduce the ankle's range of motion. "This might be the reason why regular high heel wearers report pain as soon as they kick off their high heels and walk barefoot," Csapo said. Their shortened calf muscle fibers are stretched when their heels are no longer propped up a few inches and instead press all the way to the ground.

Csapo believes that women should be able to prevent injuries, and overcome some of this pain, through stretching exercises, but this might not mitigate the risk entirely.

"The physiological strains you normally experience as you're walking are completely different as soon as you put on high heels," he said. "In the long run, this may have consequences."