Does the shoe fit?

active people take up to 12,000 steps per day. At approximately three times body weight and averaging up to 1,500 footsteps per mile, a 150-pound runner, over the course of a four-hour marathon, absorbs nearly 12 million pounds of impact. Add the fact that asphalt is 20 times harder than natural surfaces, and concrete some 50 times harder, and you've got a situation in which a lot, literally, is riding on your shoes. In addition to his podiatry practice, Running & FitNews editorial board member Paul Langer, DPM, has spent years fitting runners in his local running shoe store. He recently shared his thoughts and experiences on how to shop.

Shoe Overview

Though many varieties of running shoe defy broad categorization, the three major classes of running shoe are cushioned, stability and motion control shoes. Choosing the right shoe often means deciphering loads of advertising jargon and overcoming common misconceptions about what we really need shoes to do.

Cushioned shoes, which are made from the most flexible material, offer no stabilizing devices and are therefore made for light, efficient runners with no history of injury. The shoes are not a good choice for larger runners, over-pronators or those with knee problems. Despite advertisers' claims that this or that brand has manufactured a more cushioned, and therefore superior, running shoe, the overall value of cushioning has come into question as of late. Soft shoes are less stable, contribute to less efficient running and break down sooner.

"In my experience, 75 to 80 percent of runners should be in the stability category," says Langer. "The most cushioned shoes have not been shown to decrease impact forces or injuries," he notes. "But stabilizing features have been linked to improved lower extremity alignment and decreased injury risk."

A stability shoe represents the middle category and offers a desirable combination of cushioning and motion control. Mild over-pronators and those with an externally rotated gait do well with these shoes. Furthermore, they last up to 100 miles longer than cushioned shoes. However, these shoes may not provide enough stability for those with flat feet.

With a midsole made of dual-density foam, the third category of running shoe is the heaviest, and offers motion control. Motion control shoes provide maximum medial (inside) stability and are therefore good for heavy runners and, Langer feels, pretty much exclusively so. Ideally, he sees motion control shoes as best suited for walking, not running. He does maintain that in his experience those 180 pounds and over, and severe over-pronators with flat arches, do well in motion control shoes.

Shoe Shopping

Trial and error in a running shoe store is inevitably the only way to ensure proper fit. Look to buy in the evening if possible, when feet tend to have swollen a little bigger. Find an experienced staff member and give them an old pair of shoes. If you already wear orthotics, bring them along. Expect the store employee to perform a foot and gait analysis. Buying the right shoes remains wholly contingent on understanding your needs and goals; Langer emphasizes that runners should beware of any salesperson who recommends the shoes he or she runs in.

A running shoe should fit like a sandal with a snug heel, a strap across the instep and wiggle room for your toes. The longer the distance, the roomier a shoe's length. Marathoners should look for up to a thumb's width of space at the front. It's also a good idea to check both shoes carefully for fit; they are often made in different assembly stations of a factory.

Because shoe companies constantly change shoe names and model numbers, Langer advises patients to instead memorize specific shoe features, for example, "a long medial post with a snug midfoot." And brand loyalty has its limitations. It's dangerous to make assumptions about the "fit characteristics" of certain brands, because nowadays most manufacturers offer a range of shapes--shoes in multiple widths, for instance.

To Dr. Langer, still another marketing-based problem is that, while theoretically possible, "running shoe advertising greatly overstates energy return." Thinner, denser midsoles best achieve what we ask of running shoes: to stabilize gait, to provide enough sensory feedback to allow shock-absorbing behavior to occur naturally, and to strengthen--or at least not weaken--intrinsic muscles. And keep in mind that "supportive" is almost always a meaningless marketing term.

Today's obsession with shoe weight, especially among distance runners, is largely unjustified. Lighter shoes permit higher transmission of shock and are less stable, so the energy cost of a heavier, more impact force-resistant shoe--at 0.342% per ounce of shoe weight--is, if not entirely negligible, the lesser of two evils.

A Note About Orthotics

Lastly, corollary to the realization that more cushioning doesn't mean less injury lies a discussion of how an orthotic works. A midsole stability device alters the position of the inner aspect of the rearfoot, guiding the whole foot away from excessive pronation. Never wear orthotics with cushioned shoes. Langer likens this to building a house on sand. Orthotics decrease abnormal motion; cushioned shoes increase it. Runners should not expect to self-diagnose; running gait analysis is the only real way of determining who over-pronates. For a general overview of pronation, see Mar/Apr 2005, "Which Way Do Your Ankles Curve?"

(Understanding the Biomechanical Effects of Running Shoes, Paul Langer, DPM, AMAA 34th Annual Sports Medicine Symposium at Boston, April 2005)