Pronation and Supination
During a normal gait, pronation and supination normally occur in the foot. Pronation is very important for shock absorption. During foot strike, the foot goes through many changes—it begins to roll inward, everting slightly, and the arch flattens. This is called pronation. It is a normal action—one that takes place in every step in every healthy foot. The purpose of this is to loosen the foot so it can adapt to the surface, especially on any uneven terrain.
Following pronation, as the foot continues through its gait, supination occurs. This results in the foot turning slightly outward then changing from a flexible foot to becoming rigid so it can propel the foot and push off. During this phase the foot inverts slightly, and the arches get higher, enabling the foot to properly roll over the big toe.
A number of factors can disrupt an athlete’s normal gait. The two most common reasons are muscle imbalance and wearing shoes. Sometimes, areas above the foot, such as the pelvis or spine, can abnormally influence foot function. For example, too little or too much rotation of the hip can cause the foot to land in an abnormal position. In addition, injury, pain, and other problems that affect blood flow, cause inflammation, or disturb muscle function in the foot can abnormally alter the gait.
Most shoes change the gait by causing the stride length to become abnormally longer. This causes an abnormal heel strike—hitting the ground farther back on the heel. This is especially a problem during running, as the longer stride places more shock through the foot and into the knee, and occurs despite shoe cushioning or other shoe designs. Barefoot movement of any type does not cause the same stress.
The notion that some people are “pronators” while others are “supinators” is a gross oversimplification that is often presented to an unsuspecting public. That shoe companies make special shoes for one group or the other is an example of marketing hype. We all pronate and supinate. The reason some people excessively pronate or supinate is more often from wearing shoes, which cause muscle imbalance. This is especially a problem in children whose feet need to properly develop without shoes.
More importantly, an attempt to “help” a poorly functioning foot with a particular type of shoe or insert is an example of treating symptoms; most cases of foot dysfunction in athletes are due to muscle imbalance. Keeping the foot in a rigid, particular position maintains foot imbalance, not allowing the brain to correct the problem.
Our feet were made for walking, running, hopping, jumping, cycling, and all other natural movements. When we interfere with our natural movement, such as when we wear shoes, problems can arise. Other than in sandals and moccasins, humans evolved barefoot. For millions of years our feet were free. Suddenly, in only the past few hundred years, shoes of many types have restricted our feet, disturbed our gait, and caused untold problems to our feet.
In one sense, the foot is a highly complex structure with intricate functions that scientists are still continuing to unravel and understand. However, the awareness that the foot is a perfectly made natural part of our anatomy and can function just fine on its own will help in our appreciation of this structure and in our ability to prevent and correct most problems we inflict upon it.
