Ask any new medical student and they'll tell you that learning the language of medicine is a tough job. As young doctors, they soon come to learn that it's essential for doctors to have descriptive terms to use when diagnosing and communicating with peers and patients. Foot care is by no means exempt from needing a language to describe how the foot and ankle works. Two of the most common biomechanical terms used in foot care are pronation and supination. Let's talk a bit about these terms.
Pronation is a term used to describe the arch of the foot becoming flat. A pronated foot is simply a flat foot. To pronate means that the foot is rolling in or flattening. Supination, on the other hand, refers to a foot that is rolling out and creating an arch. A supinated foot is simply a high arched foot. You can try this yourself. Simply put your foot on the floor, and keeping the sole of your foot on the floor, roll the foot from the inside to the outside. There you go. Now you're pronating and supinating.
A pronated or supinated foot is neither a good or a bad thing. A foot that is mildly pronated may work for a lifetime without symptoms while a foot that is very pronated can indicate many different types of problems. Rigid, pronated feet in young adults may indicate a tarsal coalition. In older adults, a pronated foot may be due to a tendon rupture of the medial arch. Typically, pronated feet are a very flexible and an inefficient foot type. Supinated feet, on the other hand, are usually rigid and stiff. The high arch in a supinated foot can be difficult to treat when foot problems occur.
Once the terms pronation and supination are understood, they become an effective way to communicate with others regarding foot problems. One example is when you go to the shoe store to shop for shoes. You know the feeling; you walk into the running store and there, facing you are dozens of shoes with bells and whistles like air bladders and springs. How can you tell them apart from one another? What makes for a good choice? Well now that you know about pronation and supination, you have a jump on the average shoe customer. Here's why. Most pronated feet will loose the normal curvature of the foot from the heel to the toe, while supinated feet will increase in curvature. When I say curvature, think of the footprint you'd make when you get out of the pool. Is it straight or curved? When shopping for running shoes this is important due to the fact that running shoes come in different types of lasts. The last defines the curvature of the bottom of the foot. So a pronated foot requires a straight last shoe while a supinated foot requires a curved last shoe. Shopping for shoes can become much easier once you're familiar with these two terms.Supination and pronation are the two most common terms used when discussing the biomechanical properties of the feet.
For more information on this topic, stop by your local running store, podiatrists office or local pedorthics facility.

About the Author
Jeffrey A. Oster, DPM, C.Ped is a board certified foot and ankle surgeon. Dr. Oster is also board certified in pedorthics. Dr. Oster is medical director of http://www.myfootshop.comMyfootshop.com and is in active practice in Granville, Ohio.