You would think that overpronation is akin to a death sentence for runners if you read some of the running websites and social media commentary. You would think that it could be responsible for all the injuries that runners get and why they need the special motion control running shoes or foot orthotics to fix it. It really does get talked about in some circles that it is something quite evil and that it needs to be dealt with.
Pronation is a normal motion of the foot in which the ankle rolls inwards and the arch of the foot flattens. Overpronation is when there is too much of that normal motion. There is no clear definition of what overpronation actually is and what could be considered normal and abnormal. This problem is claimed to cause an inefficient running gait, so more energy is needed to run. It is also claimed that that a foot that overpronates can cause all sorts of problems from bunions to plantar fasciitis to knee injuries. Due to this, runners who do overpronate are strongly advised to use foot orthotics to support the foot and use the supportive types of running shoes.
Despite this, there are plenty of anecdotes of runners who can have quite a severe form of this type who never get problems and can run fast. This has led to claims that the whole concept around overpronation is a myth and is not really a problem. They claim it is invented by those who make money from foot orthotics and running shoes.
However, if you look at the actual research evidence, then yes overpronation (however you want to define it) is a problem in running. The meta-analyses and systematic review of all the data show that is a small risk factor for overuse injury in runners, but that risk is still statistically significant. This means that overpronation is a problem is runners but its probably not as big a problem that it was considered in the past.