How to fix duck feet: point them straight, wake the arch.

In my experience, shoes start it. A narrow toe box pushes the big toe in toward the other toes, the arch loses its anchor and drops, and the feet turn out to find a stable base. Sitting adds to it, with the hips spending hours rotated out. Old ankle, knee or hip injuries can lock it in, because the body adapts around them.

Some people are built with a little turn-out in the hip or shin bones. That part won't change, and it doesn't need to. The question is how much of yours is habit and how much is structure. Most people find there's more habit in it than they expected.

Because the push leaks. When the foot points out, part of every push goes sideways instead of straight back. Over thousands of steps that's lost speed and extra work for the knees and hips.

It also moves the knee off its line. With the feet out, the knee points out as the leg swings, then caves in over the dropped arch when you land. Either way it's off the second toe, which is why duck feet and knees caving in travel together. The arch usually follows too: turned-out feet and flat feet are often the same pattern.

You can often see it in the calves. With the feet turned out, the outer calf does most of the work and the inner calf stays small. Mine only started to fill out once my big toe began pressing down properly.

Build it a little every day, rather than forcing the feet straight all at once:

• Stand with the outside edges of the feet parallel, hip-width apart.
• Press the big toe down without curling it, and lift the arch.
• Keep each knee over the second toe. Not in, not out.
• Walk short stretches like that, pushing off the big toe, and build the distance week by week.
• Stretch what pulls: the outer hips and calves, with the feet straight.
• Give the toes room: a wide toe box, barefoot time at home, toe spacers.

The foot strengthening exercises guide has the drills that make the new position hold.

Months, not weeks. For my whole body it took two to three years, and every time I thought I was there, a plateau showed me how much further there was to go.

Expect the ache to move. As my feet turned in from duck-footed, the pressure shifted to my inner knees and they ached until the inner thighs got strong enough to take the load. Soreness in a new place often means the chain is waking up. Sharp joint pain means stop and get it checked.