Every runner is unique--that much is clear. But after decades of commiserating with our fellow runners, we've learned that there are a few universal constants: all runners want great comfort and fit, long-lasting cushioning, a smooth ride and an appropriate level of support. But that last point is tricky because we each have such distinct needs when it comes to support. In fact, the level of support a runner requires can change over the course of a run and, in many cases, runners have differing support needs from one foot to the other.