Overpronation is when there is excessive rotation beyond the optimum level, more specifically involving more than 15 degrees of difference in angle between the plane of the foot and the plane of the leg. It is often linked with flat feet, fallen arches and collapsed arches. When the arches are high, there is not usually sufficient pronation. This is called underpronation or supination.
Flat feet don't automatically mean you have a problem. The problem can be divided into a flexible flat foot or rigid flat foot. The rigid flat foot is one that does not change shape when the foot becomes weight bearing. i.e. it does not go through the excessive motion of pronation. Generally speaking this foot does not provide too many problems. The flexible flat foot is the type that when it becomes weight bearing the foot and ankle tends to roll in (pronates) too far. This type of person will often say I have great arches but when I stand up much of this arch disappears as the foot excessively pronates When the foot is excessively pronating and causing problems like sore ankles, feet or knees when standing or exercising then arch support is extremely important to restore the foot structure.
Overpronation can be a contributing factor in other lower extremity disorders, such as foot pain, plantar fasciitis, ankle injuries, medial tibial stress syndrome (shin splints), periostitis, stress fractures and myofascial trigger points. Overpronation increases the degree of internal tibial rotation, thereby contributing to various knee disorders such as meniscal injury or ligament sprains. The effects of the postural deviation are exaggerated in athletes due to the increase in foot strikes while running and the greater impact load experienced. When running, three to four times the body weight is experienced with each foot strike.2 If overpronation exists, the shock force is not adequately absorbed by the foot and is transmitted further up the kinetic chain.
When you overpronate your foot rolls inwards causing the lower leg to rotate inwards too. It's thought that this increases stress on the soft tissues of the lower leg causing pain and inflammation, or more commonly known as shin splints.
Non Surgical Treatment
Fortunately, there are simple things you can do to cure and correct your overpronation issues. Certain exercises help. Pull your toes back using a rolled up towel. Roll your feet over a golf or tennis ball for a minute. And do calf raises by standing up and lifting up on your toes. These all help reposition the foot and strengthen the muscles and tendons necessary for proper support. Beyond that, simple adjustments to footwear will help immensely.
Custom-made orthotics will reduce the twisting of the leg muscles as they enter the foot, by maintaining a normal alignment of the bones and joints of the foot. If the bones and joints are aligned properly, by reducing the pronation, the muscles can run straight to their attachments in the foot, without twisting to get to these bones. This action of custom-made orthotics will reduce Achilles Tendonitis shin splints; ankle, knee, hip, and lower back pain; and leg cramps. This action will also allow the leg muscles to work more efficiently, thus allowing you to walk and run with less effort.