“We found that when people walk in flip-flops, they alter their gait, which can result in problems and pain from the foot up into the hips and lower back,” Shroyer said. “Variations like this at the foot can result in changes up the kinetic chain, which in this case can extend upward in the wearer’s body.”
The researchers, in the AU College of Education’s Department of Kinesiology, recruited 39 college-age men and women for the study. Participants, wearing thong-style flip-flops and then traditional athletic shoes, walked a platform that measured vertical force as the walkers’ feet hit the ground. In addition, a video camcorder measured stride length and limb angles.
Shroyer’s team, under the direction of Dr. Wendi Weimar, associate professor of biomechanics and director of the department’s Biomechanics Laboratory, found that flip-flop wearers took shorter steps and that their heels hit the ground with less vertical force than when the same walkers wore athletic shoes. When wearing flip-flops, the study participants did not bring their toes up as much during the leg’s swing phase, resulting in a larger ankle angle and shorter stride length, possibly because they tended to grip the flip-flops with their toes.