Running Resources

Biomechanics of Running

There isn’t one shoe out there that fits everybody the same. However, runners tend to focus on what brand of shoe is best without realizing that when it comes to finding the right shoe, it’s all in the feet. Therefore, the “best” shoe depends on running biomechanics that affect the functioning of your foot.

The first consideration involves what foot type you have (high arch, flat foot or normal arch). Next is analyzing your foot strike to determine whether you are a heel striker, forefoot striker or mid-foot striker. Finally, your stride pattern (pronator, supinator or neutral) needs to be considered.

In order to get the proper fit and to maximize your running potential, pay attention to the following running biomechanics that play a big role in determining your overall satisfaction in your shoe selection.

Determining Your Foot Type:

Discovering what type of running shoe you need has a lot to do with simply looking at your feet, which is the first step to finding the right shoe for you. There are three different foot types, based on the height of your arches. A quick and easy way to decipher your specific foot type is called the “wet” test. Pour a thin layer of water into a shallow pan; wet the sole of your foot; step on a shopping bag or blank piece of heavy paper; step off and look down; and analyze the shape of your foot and see if it matches with some of the foot types mentioned below.

• Normal (medium) arch: If you only see about half of your arch you have the most common foot type, meaning you are a normal pronator (your foot can support your body weight without problem). You can wear just about any shoe but may be best suited to a stability shoe that provides moderate arch support or medial stability.
  
  If you are a lightweight runner, you may favor a stability shoe with a moderate level of arch support or medial stability. Lightweight runners may want neutral-cushioned shoes without added support or a performance training shoe that provides some support but less weight for a faster feel.
• Flat (low) arch: If you see almost your entire foot, you have a flat foot, meaning you are an overpronator (your foot and ankle have problems stabilizing your body and shock isn’t absorbed properly). Mild to moderate overpronators need stability shoes or motion-control shoes that have devices such as dual-density midsoles and supportive “posts” to reduce pronation. Severe overpronators, as well as tall, bow-legged runners or people over 165 pounds need firmer support devices.

• High arch: If you see just your heel, the ball of your foot and thin line on the outside of your foot, you are an underpronator (meaning the force of impact is not evenly distributed, resulting in too much shock traveling up your legs). Neutral-cushioned shoes are recommended for you because they have a softer midsole to encourage pronation. No stability devices should be added because they reduce pronation.

Identifying Your Stride Pattern and Foot-Strike:

First, it is helpful to define pronation. Pronation is a cycle of motion that occurs when you run or walk; it occurs when you land on the outside edge of your foot and roll inward. For most runners, pronation stops at a healthy point, but some may have heavy amounts of inward rolling (over-pronation) or not enough (under-pronation).

• Normal pronation (neutral-foot strike):
• The outside section of the heel makes initial contact with the ground;
• The foot “rolls” inward about 5 percent and comes in complete contact with the ground, allowing you to support your body weight without a problem;
• The foot rolling inward helps to evenly distribute the force of impact, critical for proper shock absorption;
• At the end of the cycle, you push off evenly from the front of your foot;
• Foot-strike is neutral, meaning the feet roll slightly inward then slightly outward again during the time it is in contact with the ground, keeping the body properly aligned.
• Over-pronation:
• The outside section of the heel makes the initial contact with the ground;
• The foot “rolls” inward more than the ideal 5 percent;
• The foot and ankle are unable to properly stabilize the body and shock isn’t absorbed proficiently;
• At the end of the cycle, the foot pushes off unevenly using the big toe and the second toe, making them do all the work; and
• Foot-strikes that roll too far inward place the body in poor alignment and increase the risk for running-related injuries. Over-pronation is associated with overly flexible arches and muscle strength imbalances.
• Under-pronation (supination):
• The outside heel makes initial contact with the ground;
• The foot “rolls” inward less than 4 percent;
• Forces of impact concentrate on the smaller portion of the foot and are unevenly distributed;
• At the end of the cycle, most of the work is done by the smaller toes; and
• Foot-strikes are supinated, meaning that they have a lack of inward roll, resulting in an outward movement of the foot. Impact is not absorbed well, increasing the risk of injury.

Foot-Strike and Shoe Selection :

• For neutral foot-strikers, you want a shoe that does not detract from how you run naturally and you can wear almost any shoe, as long as it’s not designed for moderate to severe over-pronators. Shoes with controlling devices like motion control support shoes are not recommended.
• For over-pronators, you want a shoe with the correct amount of support that keeps your feet from rolling too far inward. However, more support is better than none. Your shoes should be firm because the support of the shoe increases, keeping your body properly aligned. If you want a softer shoe, try a similar shoe from a different brand or buy a cushioned insole.
• For supinators, you want a soft, flexible shoe that rolls easily to protect your feet. Supination is a problem with natural shock absorption and it is not necessary to correct the position of the foot, but to provide plenty of protection from softer shoes.

Sources: "The Best Shoe For You", Runners World Magazine and "Pronation, Explained", Runners World Magazine.