As the summer set in, most people want to feel as free as they can be when it comes to clothes and footwear. And what can be more comfortable during summer walks than flip-flops. However, according to a new study, flip-flops can be very bad for your feet and legs.

Researchers from Auburn University in Alabama recruited 39 college-age men and women and asked them to wear flip-flops or athletic shoes while walking on a special platform. The study found that when participants wore flip-flops, they took shorter strides and their heels hit the ground with less vertical forces than when they wore athletic shoes.

Therefore, wearing flip-flops can result in altering people’s gait, “which may explain why we see some lower leg and foot problems in people who wear these shoes a lot,” study author Justin Shroyer, a graduate student in Auburn’s department of kinesiology said, according to the New York Times.

The results of the study should not discourage people from wearing flip-flops, Shroyer said. However, he added that people should wear them for short periods of time, (especially people with pain in their legs and feet), as this kind of footwear is not designed to properly support the foot and ankle during all-day wear.