People with flat feet often stand with their heels in an outward facing or everted position. This was certainly true in my case and this is evident in the pictures I took at the start of this project. Back then, standing that way felt natural to me. But in order to form an arch, the heel needed to be in a less everted position.
This straight up and down position of the back of the foot is what I refer to as "neutral heel". This is a really important concept because many of the arch building exercises need to be performed while keeping the heel in neutral.
In order to get used to moving my feet into the neutral heel position, I practiced standing with my back to a mirror so that I could see the alignment of my heels. I used my Achilles tendon as a guide and aimed to find the position where the Achilles was running straight up and down. When the heel is everted the Achilles often looks like it's curving outward.
Getting to Neutral
There are several ways to go about finding the neutral position. For me, the easiest was to shift or roll weight towards the outside edges of the feet.
Eventually, I was able to sense when I was in the neutral position without needing to check with the mirror.
Heel eversion and the opposite motion--inversion--are normal movements involving the subtalar joint inside the foot. These movements allow the foot to adapt to uneven surfaces and provide shock absorption.
People with flexible flat feet often have difficulty controlling the movement of the subtalar joint. This can result in the foot rolling in and the heel everting when weight is placed on the leg.
One of the surgical procedures tor treating flat feet is an implant that blocks motion of this joint that prevents the heel from everting. The approach I used to build arches involved strengthening the muscles and supporting structures around the joint to retrain the body to hold the neutral heel as the new normal position of the foot.