The true 'flat foot' is very rare. In fact, less than 5% of the population have flat feet with no arch present whatsoever.
The majority of us have a normal to low arch. Only 5-10% have a high arch!
However, most people with a 'normal- to-low' arch actually suffer from 'over-pronation' during walking, running and standing. This means the foot may appear normal and a clear arch is present under the foot, especially when sitting down...
This siutation changes with weight bearing; with every step we take the arches collapse and the ankles roll inwards. This is called over-pronation (or fallen arches). Pronation itself is not wrong because we need to pronate and supinate as part of our natural gait cycle. Pronation (rolling in) acts as a shock-absorbing mechanism and supination (rolling out) helps to propel our feet forward.
Overpronation occurs when we pronate too deep and for too long, not giving the foot a chance to 'recover' and supinate.
Therefore, over-pronation hampers our natural walking pattern. It causes an imbalance and leads to wear and tear in several parts of the body with every step we take!
Whether you have a true flat foot or have a normal arch and suffer from over-pronation (like 70% of the population) in both cases your poor walking pattern may contribute to a range of different complaints. Especially with age, poor aligment of the feet will cause very common conditions such as Heel Pain or Knee Pain.