In Social Media, everyone is an expert on this. Opinions vary, but facts don’t, but all so often those opinions are being stated in the ignorance of the actual research evidence.
I have written so many times about this in so many places (eg here, here and here), so lets type it slowly and make it clear:
Firstly, there is no clear definition of “overpronation” which is why I generally put it in the “x”, but we all know it when we see it. Yes, pronation is normal, but we generally lack a clear definition of when that normal becomes too much. However, we do have normative data on the foot posture index (FPI), so there is some consensus as to what is normal and abnormal. I am pretty sure most of those posting in social media about “overpronation” have no clue what this normative data is or even what the FPI is that its based on is. This is also probably complicated that the division between normal and abnormal is most likely to be subject specific and mediated by many other factors, such as tissue capacity.
Secondly, yes there is something wrong with “overpronation”. Too many in social media keep saying that it is not a problem. Yes, there are studies that show its not and yes, there are studies showing that it is a problem. This also has to be interpreted in the context of how each study actually measured “overpronation”. When you get conflicting evidence you then need to turn to the systematic reviews and meta-analyses which assess the quality of studies and how much weight to give each studies. All those most recent reviews of the preponderance of that evidence have shown the same thing: “overpronation” is a problem; it is a Risk Factor for running injury. However, it is only a small risk factor, but it is still statistically significant.
Thirdly, just becasue someone can show an example of someone who massively “overpronates” and does not have a problem is not evidence that it is not a problem. The video of Haille Gebrselassie (“the truth”) come to mind. This is no different to showing someone who has smoked cigarettes their whole life who did not develop lung cancer. Does that mean smoking does not cause lung cancer? People who use examples like that video of Haille Gebrselassie to support their case really should know better and are just showing their ignorance of causation and the actual scientific evidence and just what a risk factor is and how it works.
Fourthly, there are multiple causes of “overpronation” and if it needs to be dealt with, it is dealt with by dealing with that cause in that individual. Anyone who is advocating one particular treatment for “overpronation” really have no clue what they are talking about. There are multiple options, but the option that will only work is the one that is directed at the specific cause in each individual. You can tell how much someone in social media knows about this based on what they say you need to do to deal with it. One hit wonders are clueless, so ignore them.
Enough said … again.