There are three different types of feet:
If you're looking at your foot, you'll know you have flat feet if you don't see any arch. The bottom of your foot, from your toes to your heel, is completely flat. If you do the footprint test, your print will look like a foot-shaped blob. You won't see an inward curve from your big toe to your heel.
Problem? If you're flat-footed, you're most likely an overpronator, which means that your feet roll inward when you run.
What to Buy: You will probably need a running shoe that maintains your stability. Look for the words "motion control" and "stability" on the box of running shoes you are considering. In addition to motion-control shoes, some flat-footed runners also need to wear orthotics (custom-made shoe inserts that correct foot issues).
You should be able to easily determine if you have high arches -- you'll notice a high and definite arch on your foot. If you do the footprint test, your print will curve inward, making the middle part of your foot look very skinny. When you push your hand against the bottom of your foot, your arch will stay rigid.
Problem? If you have high arches, you probably supinate or underpronate, which means your feet roll outwards as you run. It's very important that runners with high arches periodically re-measure their feet because running will cause their arches to gradually fall, making their feet longer.
What to Buy: You need to look for flexible running shoes with a soft midsole that absorbs shock. When buying running shoes, look for options with the words "flexible" or "cushioned" included in their descriptions.
Neutral or Normal Feet
If you've examined your foot or your footprint and it doesn't look flat-footed or high-arched, you most likely have a neutral or normal foot. Your footprint will have a noticeable curve inward, but not by more than 3/4 of an inch.
Problem? As long as you pick a running shoe that doesn't counteract your foot type, you shouldn't encounter any problems. This is the most common type of foot, and it's also the least susceptible to injury provided it's outfitted with proper footwear.
What to Buy: If you have normal feet, you can choose from a wide variety of running shoes, including ones made for neutral runners or those with slightly flat-footed or high-arched feet. Don't pick running shoes that have a lot of stability or motion control.
FAQs About Running Shoes
Do I Need Two Pairs of Running Shoes?
How Can I Make My Running Shoes Last Longer?
When Should I Replace My Running Shoes?
Should I Wear New Running Shoes for My Marathon?
How Do I Keep My Running Shoes From Getting Stinky?