As I mentioned above, I have flat feet. Have worn supplementary arch supports (cast when younger, generic more recently) nearly all my life. Figured I'd give these a try. At worst I'd have expensive slippers. At best everyday "sneakers" (not a runner). Wasn't sure which way it was going when my hamstrings, back, neck and shoulders hurt the first few days (ignoring directions and wearing all day). Anyway, my posture and stride has changed and although there are foot/toe types they warn against use with, flat feet isn't on that list. If my experience is at all representative, I wouldn't add it. I know it's gonna sound fanatical, but f*%k it, I think my legs and lower back are stronger now. Coupled with the posture change, I think that's why my feet hurt less.