How can an insole help someone jump higher or run faster?

It’s not magic, it’s science. VKs act as a spring. When you bend your foot to run or jump, you are loading up the VK (storing energy). When you push off, the stored energy is returned to you. Think of archery and pulling a bow string back, or deflecting a diving board, both designed to store and release energy. Read more about how VKs work below.