Fitting the running shoe to the patient: Paul Langer, DPM, shares his thoughts.

AMAA member Paul Langer; DPM, practices podiatric medicine with Minnesota Orthopedic Specialists in Minneapolis. He is an associate clinical professor at the University of Minnesota and an experienced marathoner and Ironman triathlete. He has also spent many years working a few days a week in his local running shoe store, where it seems that in the course of fitting and advising customers he has come across nearly as many public misconceptions about running shoes as he has feet.

"Working at the store taught me that there is a lot of misinformation out there," Dr: Langer says. He sees this as partly due to the fact that much of what we know about the role of shoes in running can be counterintuitive. And he is not shy about stating that a significant portion of the confusion is more or less advertising's fault. Thirdly, often Langer has simply found that steering runners toward one shoe or another is difficult because of the "singular experience we all have with each shoe." Concepts like "comfort" are almost hopelessly subjective. On Saturday, April 16th, at the 34th Annual Sports Medicine Symposium at Boston, Langer shared a few of the lessons he has learned and trends he has observed over the years in an effort to help his AMAA colleagues guide their patients into making informed shoe choices.

Present Thinking

Dr. Langer knows that finding a proper shoe requires more than mere knowledge of feet. "It's also about knowing the shoes, understanding running injuries and knowing training philosophies," he says. "You learn about shoes by reading, asking runners how the shoes feel to them and wearing the shoes yourself." Though many varieties of the running shoe defy broad categorization, for purposes of overview, the three major classes of running shoes are cushioned, stability and motion control shoes.

Cushioned running shoes have a curved or semi-curved last. This is the shoe's footbed and variations in its material and shape vary the way the shoe performs. The curved last usually found in a cushioned shoe is the lightest kind available. These shoes use a slip last, which is made from the most flexible material. Cushioned shoes 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.

Langer has observed that "cushioning technologies"--whether air, gel, or simply foam--are largely marketing concepts with little real meaning. In fact, he questions the overall value of cushioning. 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," he says. A patient need not be a severe over-pronator to benefit from a stability shoe. In general, running shoes cause us to pronate more; stability minimizes this effect. "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."

Since cushioning is not as important as alignment in providing comfort and decreasing injury risk, the vast majority of distance-running patients would most benefit from a stability shoe, the middle category that offers a combination of cushioning and motion control. Langer reports that, unfortunately, many runners avoid this category "because of the mistaken belief that more cushioning is needed." Stability shoes have a semi-curved or straight last. They provide medial stability and a more rigid rear-foot. 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.

When guiding patients toward a particular shoe, clinicians should of course attempt to match the shape of the last to the shape of the foot: For those with low arches, a straight and inflexible board last is usually the best choice. With a midsole made of dual-density foam, this third category of running shoe is the heaviest, and offers motion control.

Motion control shoes provide maximum medial 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. The research is less than definitive on whether these shoes unequivocally provide greater stability than the more versatile stability shoe. "In fact," he says of motion control shoes, "the wider heel outsole has been suspected of accelerating pronation." Langer does maintain that in his experience those 180 pounds and over, and severe over-pronators with flat arches, do well in motion control shoes.

A post-injury return to running, then, might look something like this: A move toward greater stability and so into a stability shoe and away from the less stable cushioned shoe; followed by an over-the-counter orthotic if necessary; followed by a stability shoe with a custom orthotic if necessary; and only then a move to a motion control shoe.

Points for Patients

With a general idea of how to steer patients toward the right running shoe, it's worth now turning to specific messages physicians can deliver which Langer sees as necessary to help overcome certain conceptual misapprehensions among the running populus.

One of the first issues to address is the incorrect notion that more cushioning is advantageous. As noted earlier, unlike cushioning, stability features have been shown to decrease injury--largely by attenuating the amount and rate of pronation. The consequences of cushioned running shoes ought to be made explicit to patients: a destabilized gait and a weakened intrinsic foot musculature. Softer shoes do not lessen impact forces. Steering runners away from cushioning and toward stability is almost always a good idea.

Corollary to this realization lies a discussion with the patient about how an orthotic works. A midsole stability device alters the position of the medial aspect of the rearfoot, guiding the whole foot away from excessive pronation. Note that the shoe's heel counter doesn't necessarily control rearfoot motion, as is often assumed. Runners should be made aware that orthotics are never to be worn with cushioned shoes. Langer likens this to building a house on sand. Orthotics decrease abnormal motion; cushioned shoes increase it (as all shoes do, but cushioned shoes more than stability shoes). Doctors should also explain to patients the difference between orthotics and cushioned insoles: Adding a soft insole will not prevent injury.

Likewise, it's worth combating the notion that "supportive socks" exist. Langer explains that there simply is no fabric able to withstand impact forces equivalent to three times bodyweight, the force we endure as we land running. He often feels like much of his work at the running shoe store involves overcoming advertising messages. "Supportive" in general is a meaningless marketing term. And physicians should always emphasize that, though "stability shoe" sounds severe, this is the middle of the road choice, a well-rounded shoe with both cushioning and motion control features. A "stability shoe" has plenty of cushioning.

Because shoe companies constantly change shoe names and model numbers, Langer advises patients to memorize specific shoe features instead, 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 media- and marketing-based problem is that, while theoretically possible, "running shoe advertising greatly overstates energy return." This falls in the category of things we really don't need to pay attention to in a shoe. Runners need reminding of what we need a shoe to do. Proposed injury mechanisms influenced by shoes include muscle atrophy, altered alignment, decreased proprioceptive feedback and, therefore, diminished impact-moderating behavior. 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.

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.

What should patients keep in mind when shopping for shoes? Langer strongly advises against blind Internet pointing and clicking: Trial and error in a running shoe store is inevitably the only way to ensure proper fit. Runners should find an experienced staff member and give them an old pair of shoes. Expect the store employee to perform a foot and gait analysis. Buying the right shoes remains wholly contingent on understanding an individual's 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.

Finally, if unsurprisingly, Langer says, "A lot of runners come into the store confused about whether they over-pronate." Shoe wear patterns are not a good indicator, and the same goes for crude self-administered techniques like the wet paper towel test. Motion control devices work to keep a runner's midstance aligned such that he or she can correctly push off through the big toe, not to the inside or outside of it. This is perhaps the simplest means of conveying an extremely difficult and nuanced concept to patients. Runners should not expect to self-diagnose; running gait analysis is the only real way of determining who over-pronates.

Final Thoughts

Active people take an estimated 8,000 to 12,000 steps per day. Langer says that many running injuries begin long before an athlete laces up and heads for the open road. Work shoes can be a major culprit. And running itself is repetitive and unrelenting. At approximately three times bodyweight (depending on the slope) and averaging 1,000 to 1,500 footsteps per mile. Langer calculates that a 150-pound runner, over the course of a four-hour marathon, absorbs nearly 12 million pounds of impact. Also, patients should keep the effects of various running surfaces in mind. Asphalt is 20 times harder than natural surfaces, concrete 50 times harder.

For walkers and geriatric patients, sometimes cushioned shoes or insoles may be helpful, but this is not usually so among the running population. Even without the knowledge that cushioned shoes do not attenuate ground forces during running as well as stability shoes, there is much to be said for training the body to absorb impact biomechanically, as opposed to leaving this task to the running shoe. Unshod cultures have better developed lower extremities, and make better use of their subtalar joint, the three-dimensional motion of which can convert vertical force into horizontal force upon landing.

For more information on Dr. Langer's practice, or to request literature on running shoe recommendations, contact Paul Langer, DPM, at Minnesota Orthopedic Specialists, 612-455-2008, or [e-mail].

Jeff Venables is the editor of Running & FitNews, and a regular contributor to the AMAA Journal.