If you walk into a sporting goods store and ask for shoes, you're likely to be thrown on a treadmill and have your strides dissected on video as if you were crossing an Olympic finish line. Salespeople will give you a thorough analysis of your gait. They may break the news that you "over-pronate," rolling your foot inward to some degree at the end of each step. Don't worry! It's common—and they sell a shoe made for your specific flaw. It's all very scientific, except that it isn't.
Rasmus Nielsen, a sport science graduate student at Aarhus University in Denmark, has seen the process from both sides of the in-store treadmill. When he first started running, he was told he should buy motion-control shoes to correct his pronation. Five years later, he started working in a running store.
"I was told to advise individuals to buy stability or motion control shoes if they were pronators," Nielsen says. "I started to ask the question, 'Why do we do this?' No evidence-based answer was provided."
Since becoming a physical therapist and seeing thousands of runners in his clinic—and dealing with his own running injury—Nielsen has developed a new perspective about where injuries come from. He doesn't think pronation or supportive shoes matter much at all. To add some evidence to the discussion, he conducted a study of more than 900 novice runners.
The subjects were healthy Danes of various ages and sizes—on average, 37 years old with a BMI of 26—who didn't run before the study. Physical therapists assessed their gaits and scored each person's feet as neutral, moderately or highly pronated, or moderately or highly supinated (rolling outward). Then subjects spent the next year running as much as they wanted. They logged their miles with a GPS watch and called the study leaders for an appointment if any injury cropped up.
Whatever their gait, all subjects were given identical "neutral" running shoes. Nielsen reasoned that if matching running shoes to foot type prevents injuries, then people with pronating or supinating feet should injure themselves sooner in these shoes than people with neutral feet.
That didn't happen.
Injuries were common; more than a quarter of the new runners were sidelined by injury at some point. But people's foot types had no relation to how soon they got injured. In fact, pronators had slightly (but significantly) fewer injuries per thousand kilometers run than neutral runners did.
Nielsen isn't the first researcher to find plot holes in the story told by shoe companies. A 2009 review concluded that there was no evidence behind the way different shoe types are prescribed. In 2011, a study of female runners found that those randomly assigned to wear motion-control shoes experiencedmore injuries than those assigned to other types of shoes.
Since the current study only involved uninjured, novice runners, the authors point out that motion-control shoes could be helpful to people who've already had an injury. It's also possible that the most extreme pronators are more prone to injury; in the study, this group was so small—only 18 people—that no real conclusions could be drawn about them. Yet for garden-variety pronators, there was clearly no extra injury risk.
These days, Nielsen says he can run in any type of shoe, once he gets used to it. He thinks how people train matters much more for their injury risk. Worrying about your sneakers, he says, isn't worth it. "I would definitely advise other runners [to do] otherwise than I did."
Image: by Danielle Walquist Lynch (via Flickr)
Nielsen, R., Buist, I., Parner, E., Nohr, E., Sorensen, H., Lind, M., & Rasmussen, S. (2013). Foot pronation is not associated with increased injury risk in novice runners wearing a neutral shoe: a 1-year prospective cohort study British Journal of Sports Medicine DOI: 10.1136/bjsports-2013-092202
