If you read in many places, you would think that this thing of “overpronation” is evil and something that runners must do about if they have it. Overpronation is when the rearfoot rolls inwards at the ankle and the arch collapses. Foot orthotics and motion control running shoes are widely advocated to treat this. It is quite common to see this advanced as quite a problem in running magazine and running shoe websites. This has been linked to injuries such as plantar fasciitis, medial tibial stress syndrome and runners knee.
On the other hand, you have this video of Haille Gebrselassie running and very severely overpronation. Yet he was at the top of his game and never had any problems with his overpronation. This has led to lots of debates in professional circles and social media about this overpronation.
The reality is that if you read the actual scientific evidence (summarized here), yes overpronation is a problem, but a small problem, though statistically significant. It does increase the risk for a range of injuries in runners, but only a small amount.
The whole area is subject to many myths and to see clearly through it is that you need to stick to what the actual data and evidence shows. The above video of Haille Gebrselassie is an anecdote and not scientific evidence. As pointed out here, you can’t bring anecdotes to debates about data. There is really no debate, the evidence is quite clear on this.