The downside of flip-flops: They alter how you walk

Flip-flops are named for the sound they make when you walk, but they could have been called ouch-umphs - the sound you'll make after wearing them all the time.

This isn't just a matter of opinion. Researchers at Auburn University have found that wearing flip-flops alters the way one walks, changing the gait in subtle ways that can lead to serious sole, heel and ankle problems. They presented their findings at the 2008 annual meeting of the American College of Sports Medicine.

The Auburn researchers videotaped 39 flip-flop-wearing volunteers and noticed how they scrunched their toes to keep the flip-flops on the foot while the heel lifted in the air. This motion stretches the plantar fascia, the connective tissue that runs along the bottom of the foot, which can result in inflammation, pain and heel spurs.

The Auburn team also found that the gaits of the study volunteers had changed during the study. Their strides were shorter, and their ankles were turned in slightly, probably as a way to keep their flip-flops from falling off. The altered gait, the researchers speculated, could cause long-term ankle and hip problems.

If you're going to wear flip-flops, you might try the ones made by Fitflops or Chaco. They've been endorsed by the American Podiatric Medical Association because they have a thicker sole, good arch support, and a deep heel cup that holds the foot and helps with shock absorption.

• James P. Ioli is a doctor of podiatric medicine at Brigham and Women's Hospital, Boston, Mass.