Do Runner’s Know Their Arch Height and Amount of Pronation, and Does it Matter?: Study #2
Posted on October 03 2012
Last week I posted the results of a study published in a conference proceedings back in 2003 that addressed the question of whether runners’ self-assessment of their degree of pronation was accurate or not (i.e., do they know if they overpronate). Their conclusion was that most runners have very poor knowledge of how much they pronate when they run – in fact, they found that 70% of self-proclaimed overpronators actually fall well within the normal range when assessed in a lab.
In this post I’ll summarize the results of a more recently released study that addressed a similar question. The study, titled “Runner’s knowledge of their foot type: Do they really know?” was published in a 2012 issue of The Foot by Eric Hohmann and colleagues of CQ University in Rockhampton, Australia.
In the study, the authors used carbon paper to take footprints from 92 runners and determined their arch index using computer software. Arch index is a measure obtained by comparing the size of the middle one-third of the footprint (i.e., the arch region) relative to the overall area of the footprint (excluding the toes). Thus, higher values for arch index indicate a flatter arch, and lower values indicate a higher arch. They used previously published cutoffs to define the three arch categories.
In addition to recording arch index, the authors also conducted a clinical examination of the subjects’ feet, as well as an assessment of dynamic overpronation during walking (dynamic overpronation was indicated by arch collapse and an inward roll of the ankle during mid-stance – this seems to have been a subjective rather than objective assessment).
For comparative purposes and to address the question the researchers posed in the title of the article, each subject was asked to define their arch type as flat, normal, or high.They were also asked each whether they believed they were an “overpronator.”
Only 48.9% of the runners correctly identified their own arch type. Of the 41 subjects who scored their arch as flat, only 18 (43.4%) were found to be flat based on the arch index analysis (the other 23 were normal). Of the 48 who classified their arch as normal, only 24 were found to fall within the normal range (21 were found to be flat, and 3 were found to be high). All three subjects who scored their arch as high were confirmed as having a high arch.
Regarding pronation, only 34 out of 72 (47.2%) were able to correctly classify their dynamic pronation. Of the 38 runners who called themselves overpronators, only 4 were actually found to be dynamic pronators on the walk test (10.5% correct). Of the 34 subjects who claimed to be normal pronators, 30 were found to be normal pronators (88% correct). 19 subjects answered that they did not know how much they pronate (3 of these were found to be overpronators). Thus, in total, only 11 out of the 92 subjects (12%) were found to be dynamic pronators.
So what can we make of this? First, runners aren’t particularly good at determining their own arch height (only 48.9% did it correctly, that’s a failing grade in my class!). Second, the vast majority of people who think they overpronate do not (about 89% over self-proclaimed overpronators were “normal” in the clinical analysis!). Third, people who think they have normal pronation did a pretty good job of classifying themselves (only 4 were incorrect). In essence, this indicates that for thus subject pool dynamic “overpronation” was actually a rather rare phenomenon, and that most people who think they do it probably don’t.
Why do so many people think they are overpronators? The authors indicate that greater than 15% inward roll is frequently used as a criterion to define overpronation in shoe shops, but suggest that “…it needs to be questioned whether 15% or more inward rolling can be measured clinically at all without the use of technical equipment.” Also, misdiagnosis may be quite common due to shop clerks believing that pronation is a strong predictor of injury risk, which results in a tendency to be overcautious.
The pronation results also suggest that arch height does not correlate well with dynamic pronation (there were 39 flat footed runners, but only 11 overpronators, though which group they belonged to was not specified), which has been shown in other studies as well. Thus, if you are flat footed, it doesn’t necessarily mean you have to be relegated to the motion control wall at the shoe store (whether or not those shoes even work is another issue entirely…).
Extending this a bit further, the authors comment a bit on the significance of these findings as it relates to shoe selection. They point out that “It is currently unknown whether the wearing of “appropriately” selected and tailored running shoes adapted to the individual foot arch are needed at all. Moreover, it is also not clear whether the incorrect selection of a shoe tailored to the foot type has any clinical consequences.” Regarding the latter, they discuss the work of Knapik, who in several studies of military recruits totaling thousands of subjects found no benefit in terms of injury risk reduction to assigning shoes based on clinically assessed arch height.
The authors of the study conclude by saying the following: “…the findings of this research suggest that most runners possess poor knowledge of their foot arch type. Given these findings, it is unlikely that recreational runners are able to select a tailored running shoe to match their foot type and level of pronation.”
On the bright side, if you believe the work of Knapik, even if you get it wrong, it might not matter all that much since choosing the supposed “correct” shoe for your arch provides little benefit when examined over a large group. All of this fuels my belief that shoe fitting as it stands right now is more art than science – experimentation and working with a knowledgeable and experienced store employee who really knows shoes and is willing to think outside the box are our best bets until a better method comes along.