The More Things Change
If you’ve followed this series over the years, you know that the rolling in movement of the foot known as pronation – whether excessive or insufficient – has been associated with all manner of injuries since the science of biomechanics became popular. This truism has been accepted as gospel by just about every healthcare practitioner I’ve ever met. The only disagreement has been over how to address this so-called “abnormal” motion – orthotics, shoe type, or exercise.
Some years ago I attended an interesting seminar presented by a podiatrist who was touting a rather radical concept and design for foot orthotics. The details of his theories seemed questionable to me at the time, though not nearly as much as one assertion he made during his presentation.
What caught my attention was his belief that 95% of all human beings overpronate to some degree and should use orthotic inserts to help control this. I thought this statement to be rather incredible, since the implication, if true, would be that almost all of us are in some way “abnormal.” (Silly me; I’d always thought the “normal condition” was the one that is found in the majority of a population.)
I asked this lecturer why he would suppose that evolutionary forces would preferentially drive human development toward a condition that we generally consider abnormal and the cause of so many gait-related ailments. He admitted he had no hard, scientific evidence; rather, he offered only his own personal theory, which postulated that because our primate ancestors needed their feet to help them climb trees, they assumed a turned-in position of the foot that has led to a faulty position of our foot joints, which in turn now causes excessive pronation. (Don’t worry if you have trouble following that argument; it shouldn’t make sense because, if you know anything about evolutionary theory, it doesn’t make sense.)
Reflecting on this debate, I have since then often wondered whether we have overemphasized the importance of this so-called abnormal movement pattern when evaluating the cause for running injuries. Do we really know what is “normal” when some studies do indicate that so many individuals (though not close to 95%) appear to have a foot structure that results in either too much or too little pronation? With so many factors in play that are associated with injury risk – overtraining, body mass, history or prior injury among the most prominent – can we easily isolate any one issue as the primary cause.
Recent studies have supported my skepticism to some extent. For example:
· A study published in The Journal of Bone and Joint Surgery (July, 2006) followed 405 military recruits who completed a 14 week training program. The soldiers were examined two weeks before the training began and classified according to foot type (pronator, neutral, supinator). At the end of the training, the investigators analyzed the relationship between foot type and the development of anterior knee pain in 61 of the soldiers. They found no evidence to support the hypothesis that pronators are more prone to developing this common injury.
· 81 female runners were categorized to three foot types (neutral , pronated, and highly pronated) and randomly assigned three different types of footwear (neutral, stability, or motion control). Theoretically, these footwear types would respectively be prescribed for the three different foot types to accommodate or control their corresponding movements (e.g., motion control shoes should control excessive pronation). The expectation was that those runners assigned the “incorrect” shoe type would have a higher incidence of injury, but the results of the study (British Journal of Sports Medicine, 2011) did not bear this out. Perhaps the most interesting finding, relative to this discussion, is that every runner with highly pronated feet who trained in motion control shoes suffered an injury!
· Researchers in Denmark conducted a study recently (British Journal of Sports Medicine, 2013) that had a novel approach: they recruited 927 completely novice runners – “unbiased” in a sense, in terms of previous running injuries or training habits – to participate in a controlled training program, with the goal of seeing if those with a particular foot type (again, overpronators, underpronators, and neutral, with first two expanded to a “severe” category) would have higher rates of injury. All runners were issued the same model of lightweight, neutral running shoes, so again the expectation would be for the neutral foot runners to have the lowest incidence of injury and the severe over- and underpronators have the highest injury rate. But – as you have probably guessed – after a full year of running, there was no significant difference between any of the groups. In fact, there was a slightly higher rate of injury in the neutral foot runners than the overpronators among those who ran more than 600 miles for the year.
This is just a small sampling of the accumulating evidence that indicates we perhaps need not obsess quite so much about this particular foot motion that has for years been the main suspect as a cause for running injuries. And, accordingly, we maybe do not need to fret so much over the type of running shoe we employ in our efforts to prevent these injuries. Perhaps the bottom line is to simply go with the shoe that just feels the most comfortable.