Custom insoles cost $200-$400 but, Stewart says, support, not comfort, should be the prime purchasing factor. If an insole is comfortable or too squishy, it might do more harm than good.
"You want something firm that will support the arch and be complimentary to the ligaments, fascia and tendons of the foot," Stewart says. "Muscles are made to help you move, so if you're using the muscles of your feet and lower legs and core to hold up your posture, you're not going to be efficient as a runner. When it comes to cushion, that's the job of the midsole of a shoe." Note: You may experience a little discomfort or awkwardness when you first run in these footbed, but it shouldn't take long for your body to adjust.