The supinator. Supination is the opposite problem. Your foot rolls outward when you run, and you can tell by the fact that the soles of your running shoes are worn and compressed along the outside edge. Supination tends to put too much stress on the bones, tendons and ligaments on the outside of the foot. Because you don't pronate enough, your foot is doing a lousy job as a shock absorber. You may have trouble with ankle sprains, plantar fasciitis, iliotibial band syndrome and knee pain. Supination happens pretty much exclusively to runners with rigid feet, often with high arches. You need a flexible shoe that will give and bend where your rigid foot will not.
Look for a shoe with a very soft midsole -- it should compress fairly easily with your thumb. There should be very good cushioning in both the heel and forefoot. The heel counter should be flexible and essentially useless -- not rigid. Finally, the shoe should have a curved (or semi-curved) slip last.
The neutral foot. Here, you don't need to worry much about stability or motion control. Your foot handles the job just fine on its own, thank you very much. In fact, too much motion control may actually screw up your foot's naturally smooth action. Look for a nice, cushioned ride with a shoe that has a semi-curved slip or combination last.
The moment of truth
Now that you're well versed in shoe construction, not to mention the construction of your own foot, you're ready for the shoe store. Wondering what to do when you get there? Check out our tips on closing the deal and on caring for your new purchase.