Pronation refers to the natural way your foot rolls inward to absorb shock as you run or walk. While pronation itself is normal and helps your body redirect the force of impact with each step, if you over or under pronate you may experience pain—or be at a greater risk for injury.

If your foot turns down and rolls inward too much when you walk, you may have overpronation. This can happen among folks with flexible feet and flatter arches, and your arch may even fall or collapse as you walk and cause the heel to lean inward.

The opposite issue is referred to as underpronation, or you may have heard it called supination. This type of pronation is more common among folks with high arches that are less flexible. If you find yourself putting more weight on your heel as the heel leans outward, you may have underpronation.

If the amount your foot rolls inward or outward is within about 15 percent, you likely have normal pronation.

You can often determine if you have normal, under or over pronation by examining a pair of shoes you’ve had for a while and wear often. If your shoes tend to wear down from the edge of the heel and toward the center of your foot, you may be dealing with overpronation. Heavy wearing down on the outside edge of the shoe is a sign you may have underpronation. The best way to be sure may be to visit a medical professional (or a running specialty store) for a gait test, where an expert will observe and diagnose your pronation.