Barefoot Running and ‘Overpronation’

I previously noted that some barefoot runners claim that the height of the arch of their feet increased after taking up barefoot running; others claim no change and, much to their dismay, some even have reported a decrease in their arch height. Some have documented changes in arch shape with photographs, and others have faked them. I speculated in that previous post about a potential mechanism that would explain that variable response.

Now we have another study on this issue:

RM Russell, S Simmons
International Journal of Exercise Science: Conference Proceedings: Vol. 8: Iss. 4, Article 42.
The study of overpronation in runners has remained a subject yet to be explored. With evidence to suggest the wide range of overuse injuries caused by overpronation, this subject needs to be researched. Barefoot running has appeared in the spotlight in the running community recently, but is still a misunderstood subject. There are many theories claiming the benefit of barefoot running, yet little research to support them.
PURPOSE: To determine the effects of barefoot running on overpronation in intercollegiate cross-country runners using a customized questionnaire and the Foot Posture Index (FPI).
METHODS: Measurement of the foot posture was taken using the FPI in a multi-plane, multi-angular fashion. The foot position was in quiet standing with equal weight distributed and toes pointing forward. Using six criteria the foot posture was measured in a variety of different categories and added to create the total score. The total score was sorted into one of the five categories: severely pronated, moderately pronated, neutral, moderately supinated and severely supinated. A total score of 6 and above indicated a moderate to severe pronated foot, and a score below 0 indicated a moderate to severe supinated foot. A total of 8 female cross-country runners (n=8) participated in the experiment. To reduce the risk of injury, the runners were first introduced to barefoot walking for two weeks, three days a week, with increasing time intervals. They then transitioned progressively to barefoot running three days a week for two weeks. The measurements were divided into two groups 1) The FPI total score pre-test, 2) and the FPI total score post-test.
RESULTS: Four weeks of barefoot running training significantly decreased overpronation in runners measured by the Foot Posture Index: FPI pre-intervention total score 5.625 ± 2.875; FPI post-intervention total score 3.376 ± 2.264; t (7)=3.473, p=.010.
CONCLUSION: The data showed significant decreases in the total score showing improvement in lessening overpronation. This suggests barefoot running can significantly improve overpronation in runners.

Firstly, I not going to get into the ‘overpronation’ issues and will just leave that there (been there, done that)

Secondly, this was an abstract presented at the Northwest and Alaska chapters of the American College of Sports Medicine meeting from earlier this yr; so I have no more information on it than what is in the abstract.

Thirdly, the sample size is 8 participants. Unlike the fan boys, I do not reflexively dismiss studies as having too small a sample size just because they don’t like the results. I am going to take other factors into consideration such as any a priori sample size calculation, effect sizes etc before making a call on the sample size. In social media the biggest critics of ‘sample sizes’ are those who have never done the hard yards of doing actual real research. However, 8 is getting down there as far as sample sizes go.

Fourthly, and most importantly, there was no control group. This means the examiners who assessed the FPI at the study endpoint were not blinded to an intervention and a control group, so the potential for uncontrolled bias is so great it pretty much negates any weight that can be given to the conclusions (whatever they may be).

Fifthly, in contrast to the above results we have 2 other studies that previously looked at the same thing; unfortunately both of them still in abstract form. This one with 5 subjects reported no change in arch height with minimalist footwear (it was also uncontrolled like the above one, but was over 6 months whereas the above one was over 4 weeks);and this one over 10 weeks with 39 subjects and with a control group so assessors where blind found no change in arch height.

So where does this leave us? None the wiser unfortunately. The strongest of the 3 studies (control group; larger sample size and blind assessors) is still not published in full (and neither are the other two)

As always, I go where the evidence takes me until convinced otherwise …. I still believe that the effect of barefoot running on arch height (‘overpronation’ or whatever you want to call it) is subject specific for the reasons I speculated previously.

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