Feet bear the full force of our bodyweight for countless hours; a force which is magnified during activities such as running or jumping. Unfortunately, this also means that problems with the feet have a tendency to work their way upwards, resulting in complications for the ankles, the tibia, the knees, or the hips. Not sure what we mean by foot problems? First, let’s define pronation versus supination.
Pronation is an inward-rolling of the arch or the ankle. Individuals who tend to stand, walk, or run in this position are known as “pronators”, and they typically appear to be flat-footed (low arches). In contrast, “supinators” roll outwards at the arch or the ankle, thus they appear to have high-arched feet. These conditions may seem innocuous at first glance, but when we consider the lifelong duty of the feet, we understand that small, individual differences are magnified across the span of many years. Next, we will discuss the importance of the arches.
The arch of the foot is actually divided into 3 sub-structures: the medial longitudinal arch, the lateral longitudinal arch, and the transverse arch. Together, they work to absorb much of the impact of each step we take, storing the energy much like an elastic, and then releasing it as we push off for our next step. In short, they improve our movement efficiency while decreasing the stress placed on the structures above (i.e., the knees).
Here’s an example of the danger associated with excessive pronation or supination. A study by Becket et al. (1992) looked at 50 individuals who had suffered an injury to the ACL and 50 individuals who had not. They discovered that the ACL-injury group tended to exhibit more pronation than the non-injured group, as measured by the navicular drop test. These findings suggest that pronators may be more likely to suffer a severe knee injury.
Beckett, M., Massie, D., Bowers, K., & Stoll, D. (1992) Incidence of hyperpronation in the ACL injured knee: a clinical perspective. Journal of Athletic Training, 27, 58-60.