Several years ago, Auburn University's biomechanics lab (Dr Wendi Weimar and doctoral student Justin Shroyer) ran a study on the biomechanical effects of a flip flop. This study included 39 male and female college-age volunteers that were measured in flip flops vs. regular athletic shoes utilizing biomechanical evaluation equipment including digital filming and pressure mats. Differences in pressure, movements of the hips, legs, knees, ankles, feet and toes were evaluated also. Their findings were significant and consisted of modified gait patterns. Listed below are injuries that can occur due the poor mechanics of a flip flop:
- Overuse injuries such as stress fractures or joint strains can occur more easily. Flip flop wearers were found in the study to take shorter steps. This increases pressure across the foot and can produce the typical "march" fracture. This could also occur due to the "shuffling" gait that occurs because scrunching of the toes caused "turning off the muscles that would bring the toes up." per Dr Weimar.
- Ankle sprains occur more commonly due to increased flattening of the foot due to poor support or even lack of midfoot support, leading to pronation or supination off the flip flop.
- Joint injury or Hammer toes. Commonly flip flop wearers were found to scrunch the toes to help keep the sandal on. This curving or scrunching of the toes can lead to accommodation of feet including curling of toes (hammer toes) or even injury to the toes or the toe joints.
- Heel Pain or Plantar Fasciitis. Due to the lack of support and a commonly tight Achilles tendon (heel cord), the most common flip flop related pain is heel pain or arch pain that hurts first step in the morning and progresses throughout the day.
- Toe Injury (Contusions, Bruising, Stubbing). Shoes should typically have protection for the toes. In a flip flop, no protection is provided from kicking a door frame, a rock or even a curb. Things that are dropped will fall on the foot (unprotected) and can cause injury.
- Sunburn. A foot that has commonly been in a shoe during the winter can easily be burned in the hot summer sun when completely unprotected.
- Fractures. Recently a patient broke her foot by running in flip flops and catching the flip flop on the curb. This created significant fractures to the foot both because of the biomechanics of how she was running and the unstable shoe that caught.
Injuries of other types can also occur. In fact, biomechanically (as shown in multiple studies) the flip flop should be limited to jaunts to the pool or beach. Can they be utilized at other times? Yes, but only in moderation. Find a good looking sandal with more protection and support for your foot or even better, where a good supportive athletic shoe when doing the mall trips, long walks or amusement park visits. Your feet will thank you and you will have less time spent recovering from an injury that didn't need to occur.