Overpronation is allegedly a problem that you see all over the web and on running and fitness websites and is supposed to be a the cause of a lot of injuries. Overpronation occurs when the ankles roles inwards and the arch collapses. The problem is then supposed to affect the biomechanics of the foot and cause a number of different injuries in the foot and lower limbs. There are lots of different opinion on the web from so called gurus and lots of misinformation. This one is probably the best discussion you can find on the topic and the misinformation. From what I can understand is that there are many different causes of overpronation, so therefore many different treatment options depending on the cause. There is no one blanket treatment for each person who overpronates which is what you see advocated by those who obviously do not know what they are talking about (and there a a lot in the fitness industry that do that!). This is also assuming that the problem actually needs treating. It only needs treating if it is actually contributing to the problem that the runner actually has. There are so many myths on this and all runners should read this.