In response to a question about high heels, heeled shoes are a harbinger of a lot of bad things.
Locally, the slack in the heel cord is met with increased tone with you try to use it or stretch it a lot, aka normal function without the heels. You run into the plantar fascitiis, achilles, calf, etc. issues. One of the correlates is that a lot of people actually feel better with a heel in the short term like with heel cups or Nike Shox.
The whole problem is not so much what is happening locally at the heel/foot, but the anterior weight shift that PF puts on the whole body. Because the heel provides adequate proprioception to hang in this position, it immediately puts you into the lower-crossed. Walking on your toes is more threatening without “feeling” something at the heel, so you are more active in the core and glutes. But in heels, there is no such incentive, and you hang in the anterior pelvic tilt where it’s easy.
From there, the littany of lower quarter and back issues come about. But it’s about the anterior weight shift from the heels, and how you choose to counter it. Are you doing it with passive structures, or are you doing it with force couples that stabilize the pelvis?
When we have kids come in with Shox or garbage shoes, they train barefoot. We have fun with it messing with them, but it is a fantastic excuse to train barefoot. We have seem time and time again that even the “best” shoes add some stability that influences the FMS and SFMA. That’s okay, but if you can train in a more challenging environment, I just don’t think you can lose.
But, orthotics are part of the answer in a corrective approach. I would be a hypocrite if I said otherwise because while I don’t deal with orthotics much, the Mulligan mobilization with movement resets the foot with expectations of improved knee pain. And that’s exactly what happens. But I think while the orthotics often abolish pain, they more often, when used by dumb people, lend to ignoring the proximal issues. Sometimes they fix automatically. Most of the time, I think that’s just luck.
I have seen matters made even worse with rigid posting acting as an RNT. If someone pronates, which is just valgus collapse at the foot, RNT says make the pronation worse to get a reaction into supination. But if you give them proprioception into supination, the aberrant mechanical mover is going to integrate that into pronating more. A stronger post can be proprioceptively facilitating a stronger push into pronation. Bad news, bad news.
Buddying off the other topic, I ended a terrible conversation with a loser podiatrist by telling him that I never met a functionally pronated foot that the hip couldn’t fix.