Orthotics may be as common as water bottles among runners and walkers, but the mass-marketed arch supports may actually increase force on the knee, possibly contributing to knee osteoarthritis, a deterioration of the cartilage.
In a study in this month's issue of Medicine & Science in Sports & Exercise, a group of 22 male and female recreational runners were given basic running shoes (ones with no high-tech structural elements such as shock absorbers). First they ran and walked in just the shoes, then they ran and walked in shoes with over-the-counter cushioned arch support inserts. The runners were analyzed via infrared cameras to track motion of the knee joints. A special treadmill measured forces the runners applied while striding.
