The Flip-Flop Flap

It is said that in Canada there are two seasons, winter and construction. In the footwear industry there is a winter and flip-flop season. When the heat rises people turn to the EVA (ethyl vinyl acetate) based ''sandals'' for their fashion, lightness, and airiness. However a recent study has proven what foot specialists have know for years... that wearing flip-flop sandals leads to lower limb pain and injury.

''We found that when people walk in flip-flops they alter their gait, which can result in problems and pain from the foot up to the hips and lower back.'' said Justin Shroyer, a biomechanics doctoral student.

The research done at Auburn University's Department of Kinesiology had 39 recruits (men and women) walk on a force plate., The subjects were videotaped to measure vertical force as well as stride length and limb angles. The subjects wore thong-type flip-flops and tranditional shoes. The results were that when wearing flip-flops the recruits took shorter strides and had less vertical force on their heels than when wearing traditional footwear. It was proven that study participants did not bring their toes up as much during the leg's swing phase, resulting is a shorter stride length. This was probably due to the tendency to grip the flip-flops with their toes to keep them on their feet. It is always humourous to see athletes who have a significant amount of support in their athletic footwear walk into the office wearing flip-flops and complaining of lower leg and foot pain.

The bottom line is that flip-flops have no support value whatsoever. Flip-flops are made of a very low durometer (hardness) of plastic. That is what gives them their lightness and the appearance of shock absorption. However, the lower durometer EVA means the flip-flops compress easily which leads to early breakdown of shock absorption. In the flip-flop there are no control features such as heal control or arch support. What support some of them do have will breakdown easily with pressure. This lack of support will lead to lower limb and foot discomfort including shin splints and metatarsalgia (pain in the ball of the foot). In 2002 a British study found that 55,100 men and women went to hospitals with flip-flop related complaints.

In the thong style flip-flop the plastic piece that goes between the great toe and the second toe has led to increased incidence of a pinched nerve (neuroma) between the first and second metatarsal heads. There is also a greater chance of blistering in this area. There have also been reports of chemical burns from the plastic that encases the foot in poorly manufactured flip-flops. We don't suggest that you throw all your flip-flops out, however we do recomend that they be worn for short term benefits only, such as post-game relief from athletic shoes, pool decks, and sandy beaches. Flip-flops are an excellent shower sandal to help prevent the spread of warts. Flip-flops were not meant to be worn as primary footwear, nor to be worn all day or for long walks.

If you develop lower limb discomfort, perhaps you should check your footwear, If your pain persists see a Canadian Certified Pedorthist and get out of your flip-flops.