Excerpt from the book, Tread Lightly by Pete Larson and Bill Katovsky. Here they discuss a very interesting point that I have been referring to – we have no evidence that traditional running shoes prevent, reduce, or cure injuries to runners.
In 2011, a remarkable paper titled “The effect of three different levels of footwear stability on pain outcomes in women runners: a ran-domised control trial” was published by Michael Ryan (then at the University of British Columbia) and colleagues in the British Journal of Sports Medicine. One of the coauthors of this study, Gordon Val-iant, works for the Nike Sports Research Laboratory, and Nike provided footwear and funding for the study. Keep this in mind as we go through the results—the study was supported by Nike, the biggest sports shoe manufacturer in the world, and they allowed it to be published. In their introduction the authors state the following surprising detail: “. . . de-spite over twenty years of stability elements being incorporated in run-ning footwear there is, as yet, no established clinically based evidence for their provision.” Shocking, isn’t it—despite twenty plus years of use, we have no data showing that pronation control elements in shoes are accomplishing anything of value for runners in relation to injury pre-vention. The study then goes on to point out that “Motion control run-ning footwear has yet to be proven to prevent running-related injuries.” Huh? Aren’t these the shoes assigned to those who have the greatest risk of succumbing to an injury caused by excessive pronation? But there is no evidence or proof that they actually work to prevent those injuries? So the big question is why has the athletic footwear industry been so long wedded to a shoe-design and fitting model that has never been proven to actually work? Given the lack of data on efficacy of pronation-control devices in running shoes for injury prevention in runners, Ryan and his colleagues decided to put the paradigm to the test. They designed a study whose goal was to determine how female runners assigned to the three categories of footwear based on their foot posture index would fare in terms of pain and injury experienced while training for a half marathon (note: foot pos-ture index is an indirect way of determining pronation through various measures taken from the foot and ankle). A total of one hundred and five women were classified as either neu-tral (fifty-one women), pronated (thirty-six women), or highly pronated (eighteen women). Now here’s the really interesting part. In a shoe store, the neutral women would be assigned a neutral shoe, the pronated wom-en a stability shoe, and the highly pronated women a motion control shoe—got it? In the study, however, the researchers took each of the three groups of women (neutral, pronated, and highly pronated), and broke them into sub-groups so that one-third would get a neutral shoe (Nike Pegasus), one third would get a stability shoe (Nike Structure Triax), and the final third would get a motion contro shoe (Nike Nucleus). This was done for each of the pronation groupings, so that there would be some women in each pronation category wearing each type of shoe (i.e., many of them wearing the “incorrect” shoe for their foot). The women in the study were then sent off to take part in a thirteen-week training program to prepare for a half-marathon to be run in Van-couver, British Columbia. Estimated weekly training volumes started around twenty kilometers and rose to a peak of about forty to forty-five kilometers. Over the course of the training program, the researchers re-corded the number of missed workouts due to injury by each runner, and collected reports of pain at rest, during daily living, and following runs. Ultimately, only eighty-one of the women wound up completing the study (for a variety of reasons, twenty-four women dropped out). The results showed the following:
1. 32 percent of the women missed training days due to pain over the course of the study. Another way to think of this is that there was an injury incidence of 32 percent in this population of runners, which is in line with other studies on running injuries. 2. Motion control shoes “resulted in both a greater number of injured runners and missed training days than the other two shoe categories.” In other words, motion control shoes faired very poorly all-around. 3. Every runner in the highly pronated group who wore a motion control shoe reported an injury. In other words, all runners (yes, all of them . . . 100 percent!) who were supposed to be wearing a motion control shoe based on their degree of pronation got injured. The sample was small, but this is simply astonishing. In fact, highly pronated runners actually fared better in neutral shoes! 4. Neutral runners experienced greater pain during or after runs when wearing neutral shoes than they did when wearing stability shoes. Al-though the authors point out that the difference may not be clinically significant, it is once again amazing that neutral runners fared better with a shoe that would not have been “prescribed” for them in a shoe store based on their degree of pronation. 5. Pronated runners experienced more pain during or after runs if wear-ing a stability shoe than if wearing a neutral shoe. Again, they did better wearing the “wrong” shoe for their feet.
So what can we conclude from these findings? Motion-control shoes offered little benefit to the runners in the study, and in fact were more likely to cause pain and injury than any of the other shoe types. The fact that every single severe overpronator experienced an injury in her motion control shoes demands further investigation. In the absence of other evi-dence, why should anybody wear them for preventing a running injury? The authors themselves conclude, “This study is unable to provide sup-port for the convention that highly pronated runners should wear motion control shoes.”
Second, this study showed that neutral runners did better in stabil-ity shoes, and pronated runners did better in neutral shoes. Try to make sense of that finding! This is a complete reversal of what would be expect-ed based on the current pronation-control model. This rather startling result calls into question the manufacturer practice of classifying shoes based on degree of pronation control, and it also raises serious questions about the fitting process employed by many shoe stores—should they re-ally be placing runners in shoes based on their degree of pronation? Ryan’s study offered this rather frank assessment of the status quo: “Current conventions for assigning stability categories for women’s run-ning shoes do not appear appropriate based on the risk of experiencing pain when training for a half marathon. The findings of this study sug-gest that our current approach of prescribing in-shoe pronation control systems on the basis of foot type is overly simplistic and potentially injuri-ous.” This doesn’t instill much confidence in the current system, does it? By allowing publication of a study that openly states that there is no clinical data showing that shoes designed to control pronation do anything to prevent injuries, Nike took a great risk. It’s comparable to a pharmaceutical company selling a drug for over twenty years that has never been shown clinically to be of any benefit to a patient who suppos-edly needs it. It makes one wonder if the whole pronation-control shoe paradigm is nothing more than a giant marketing gimmick whose goal is to scare consumers into buying shoes based on fear of injury. It’s a time-honored marketing tactic—convince consumers of a need, and provide a product that supposedly fulfills it. In this case, the need is a neutral gait in order to reduce injury risk, and the products are the shoes that promise to correct gait to meet the need. Furthermore, in the absence of evidence showing that running shoes either do or don’t reduce injury risk (or maybe even increase it), why stop making something that continues to sell and has come to be expected by consumers?
Dr. Campitelli is a podiatrist in Akron, OH specializing in foot and ankle surgery with an interest and enthusiasm for running as well as helping runners with injuries. For the past several years he has been treating running injuries in patients by fixing their form and transitioning them to minimalist shoes. Having treated runners with all types of injuries through conservative measures with orthotics and shoe gear changes to reconstructive foot and ankle surgery, Dr. Campitelli has brought what works best and is most current to his practice as well as the Akron and Cleveland running communities.