The way in which the foot functions or works may have a an important influence on the rest of the body. The feet are widely considered as the foundation of the body and just like the tall building analogy, if that platform is not correct, then something might go wrong higher up. There are various types of biomechanical problems that can impact that foundation and how the feet interact with the surface. That interaction will have different affects higher up the body.
One of the problems that may go wrong is something that is commonly termed overpronation. This term is frequently used and misused, so should probably not be used. The word refers to the foot moving inwards at the rearfoot and the mid-foot (arch) of the foot collapsing. This really is quite a normal movement and is only a issue if there to an excessive amount of it. Why the word is such a problem is that there is no understanding as to what is too much and what is normal. This leads to plenty of uncertainty about overpronation in research as well as in clinical practice, especially when decisions have to be made if the overpronation should be addressed or not.
The outcomes that this issue can have on the body are believed to vary from bunions and heel spurs in the foot to lower leg and knee joint conditions in runners. There are several methods to treat it, again with a lot of difference of opinion between health care professionals as to the best way to deal with it. Rationally dealing with the overpronation really should be geared towards the cause and there is no such thing as a one size fits all. When the condition is due to tight calf muscles, then stretching of those muscles would be the sensible approach. When the issue is the control of muscles at the hip, then the therapy ought to be aimed towards that. If the problem is because of weak foot muscles, then that is the best place to start the rehabilitation with exercises. If the problem is due to a bony alignment trouble in the foot, then foot supports tend to be used.