Flat feet is the common term used for foot pronation. Foot pronation is basically when the inner arch of the foot becomes lowered to the ground. Flat feet can be a cause of ankle, knee, hip and lower back pain. Some factors that can cause foot pronation include age, genetics, obesity/overweight and pregnancy.
In the past it was believed to be a sign of a poorly structured and functioning foot. However, now it has been found to be no more prone to injury than any of the other foot type. It is believed the activities we do and the way we move have more of an influence on foot injuries and pain.