When walking or running, pronation is a slight roll to the inside of the foot as the arch flattens through your step to distribute the force of impact to the ground. It's important to understand your pronation type when choosing the proper running shoes as most today are designed for a specific type of pronation.
Underpronation, also known as supination, occurs when the foot doesn't roll to the inside enough. This prevents the foot from absorbing impact and can lead to stress fractures. To check your feet for underpronation, look at a pair of well-worn shoes. If they lean outward and show signs of heavy wear on the outside edge, then you are probably an underpronator. Shoes with lots of flexibility and cushioning are suggested for this foot type.
Neutral pronation occurs when the foot experiences a normal or average range of pronation instead of overpronating or underpronating. You are likely a neutral pronator if the soles of your shoes show wear in an S-shaped pattern, from the outer heel to the big toe. The suggested type of shoe for this foot is a stability shoe, which helps slow the basic pronation movement through moderate cushioning and support.
Overpronation occurs when the foot rolls to the inside too much. As a result, the shock from the foot's impact doesn't spread evenly throughout the foot and ankle and causes instability, which affects running efficiency and can lead to joint inflammation in the knee and hip. The shoes of an overpronator will show extra wear on the inside of the heel and under the ball of the foot, especially the big toe. This foot type would benefit from structured cushioning or maximum support shoes.
In severe overpronation, the feet and ankles can rotate too far inward just during standing. Motion-control shoes with a firm heel are designed to help correct the overpronation.