Overpronation is a phrase that causes plenty of angst among podiatrists and running footwear shops because it brings about a huge amount of confusion and argument. Pronation is really a movement of the foot in which the ankle rolls inwards and the mid-foot (arch) of the foot flattens. This is a normal healthy movement which is essential for normal foot biomechanics and shock reduction. Overpronation is said to be the term employed to explain if you have an excessive amount of this normal pronation. The first part in the controversy is precisely what is normal what is actually abnormal and just where is the threshold of the division between normal pronation and overpronation. There are strong views on every side of this controversy and there doesn't look like any solution in the discussion on the horizon.
The reason why the topic creates a whole lot of discussion is that overpronation has been regarded as a key aspect in overuse injuries in runners. Podiatrists often use foot orthoses to manage the condition and running shoe manufacturers design running shoes to help runners which have the problem. This suggests there is lots of vested interest in it. The problem arises is that the research evidence shows that, yes, overpronation generally is a risk factor for a running injury, however it is not really a large risk factor. It's further complex by a lot of runners who may have rather severe overpronation and don't develop any problems and never need foot supports or running shoes with the motion control design features. That will not help fix the controversy nor help clinicians make decisions re foot supports and for running shoe retailers on advice in regards to what needs to be the correct running shoe. It really comes down to clinicians and running shoe retailer’s individual experience and expertise and making decisions in the context of what is ideal for the individual athlete.