I don't get the concept of arch supports

So an arch is one of the strongest structural supports known. It gets its strength from the weight pushing down on it, which pushes everything together and makes it stronger. In fact, the worst thing you can do to an arch is support it from underneath. If an architect suggested supporting an arch from underneath, they’d put him away.

So why are “arch supports” in shoes so popular? Doesn’t that fly in the face of the point of having an arch there to begin with? And yes, I know, some people have problems with their arches, but it hardly seems like destroying the arch by supporting it from underneath is the answer. How could this possibly be a good idea?

I’m pretty sure the only things a biological foot arch has in common with an architectural self-supporting arch is it’s shape and it’s name. If you look at a foot skeleton, you certainly don’t see anything that looks like an architectural arch – rather you see a bone structure that looks like it would flatten with sufficient weight put on it. I don’t think the physics of one are transferrable to the other.

I’m not a doctor, podiatrist or otherwise, though.

An arch, such as a stone bridge, as an architectural structure is very strong, as it is constructed to move/carry loads accordingly. Block by block, with a keystone in the middle, the arch is indeed strong relative to other options.

The ‘arch’ in your foot is a physical structure, not an architectural one. It has the shape of an arch. It does not have the components of an engineered arch. While it does have bones to help form the arch, bones are not exactly rigid. Stones? Cement? Much more so.

Because unlike a stone arch, the arches in our feet are put together in a way that they have considerable give to them. This makes them good shock absorbers but also means they can become too weak to provide the support they’re supposed to. I have arches so flexible that without support they completely flatten out under my weight.