Foot type is determined by the shape and structure of the foot. Foot type affects the reduction of impact on the foot while walking, jogging, or running. Specifically the shape of the arch causes different levels of pronation in feet.
Pronation is the rolling motion of the foot from heel to toe while walking, jogging, or running. Pronation includes Neutral Pronation, Underpronation, and Overpronation.
Neutral Pronation is hitting the outside of the heel and ball of the foot evenly across the foot to properly reduce impact on the foot.
Underpronation occurs when more weight is absorbed by the outside of the foot rather than evenly through the foot strike.
Overpronation occurs when there is too much roll on the inside of the foot, consequently distributing the weight and shock of impact more heavily on the inside of the foot rather than evenly throughout the foot as found in Neutral Pronation.
Pronation will likely be evident by looking at the wear inside or on the rubber sole of a shoe. If the inside side is more worn than the rest of the shoe then the person overpronates. When the outside side of the shoe is more worn than the inside side then the person underpronates. If the wear is equal across the forefoot then the person is a neutral pronator, or has neutral stride.
The height of the arch in the foot determines pronation, and therefore, foot type.
Determining Arch Height
The arch height of a foot can be determined by a wet test. To take the test, stand normally on a paper bag for about ten seconds after wetting each foot. The resulting imprint will show whether the person has a normal arch, a low arch, or a high arch.
People with a normal arch have a distinct curve along the inside of the foot with a band slightly less than half the width of the foot connecting the heel and toe. People with normal arch are likely to have a neutral stride.
People with a low arch do not have a distinct curve along the inside of the foot. The imprint taken in a wet test will show nearly the entire foot. People with low arches are more likely to overpronate which can result in injuries.
People who have a high arch in the foot show only a very thin band connecting the heel and toe in a wet test. People with high arches are more likely to underpronate.
Pronation and Arch in Athletes
Athletes with different foot types should look for running shoes that specifically treat their arch and pronation to avoid injury. Running shoes generally come in straight, curved, and semi curved shapes.
Overpronators should wear shoes with a straight shape. Overpronators should also look for a motion control shoe, which prevents the foot from rolling too far by providing maximum support. Shoe manufacturers usually include a medial post or rollbar to accomplish motion control. The medial post is basically a solid piece of material on the inner part of the shoe that resists the inward roll of pronation. Orthotics are also a popular method of support for athletes who have flat feet.
Underpronators should wear a shoe with a curved shape. Underpronators should also look for a cushioned shoe to allow the feet to roll inward and absorb shock.
Neutral Pronators should look for a running shoe with a semi curved shape. Stability shoes usually offer a blend of cushioning and support that is beneficial to people with normal arch and pronation.