In our previous post, we discussed what subtalar neutral and forefoot varus are and how they play a key role in determining whether someone pronates—go check it out if you haven’t seen it yet! This post will elaborate on that and focus on the difference between pronation and flat feet.
In the previous post, there is a visible (albeit relatively low) arch when the foot is placed in subtalar neutral. However, that arch disappears when the ball of the foot comes down to the ground and the foot relaxes. Similarly, one could have an arch when the foot is non-weight bearing but becomes flat when weight bearing. In the video below, the foot has a visible arch when lifted off the ground, but again, disappears as soon as it’s lowered and the ball of the foot comes down. Notice how in both anterior and medial views, the lateral (outer) side of the foot hits the ground first—this is indicative of forefoot varus!
Looking at the arch in non-weight bearing positions and weight bearing positions can sometimes offer some insight as to whether you pronate or truly have flat feet. If you have an arch (regardless of how high or low it is) when non-weight bearing but your foot flattens out when weight bearing, then you pronate. And if your foot is flat in both scenarios, then you truly have flat feet. However, the only way to truly tell whether you pronate or flat feet is to put the ankle in subtalar neutral and assess whether there is forefoot varus.
For example, if the ankle is in subtalar neutral and an arch (regardless of height) forms but the person has forefoot varus, then they do not have actually flat feet—they simply pronate. However, if the foot does not exhibit forefoot varus in subtalar neutral and does not create an arch, then the person doesn’t pronated and truly does have flat feet.
Since the position of the feet in subtalar neutral determines the degree of pronation, the arch collapsing is not the real reason why people pronate. It’s simply an effect due to forefoot varus and therefore, an arch support is not the key to fixing your pronation issues!