Minimalist shoe vs conventional shoe for plantar fasciitis

by admin on March 7, 2010

I got am email asking me what I thought of the recent study in the Physician and Sports Medicine about those with plantar fasciitis improving more in barefoot or minimalist shoes (Nike Free) compared to conventional shoes. Here is the abstract:

Plantar fasciitis is a common injury to the plantar aponeurosis, manifesting as pain surrounding its proximal insertion at the medial calcaneal tubercle. Pain is typically worse in the morning when getting out of bed, and may subside after the tissue is sufficiently warmed up. For running-based athletes and individuals who spend prolonged periods of time on their feet at work, plantar fasciitis may become recalcitrant to conservative treatments such as ice, rest, and anti-inflammatory medication. Exercise-based therapies have received only limited attention in the literature for this common problem, yet they are becoming increasingly validated for pain relief and positive tissue remodeling at other sites of similar soft-tissue overuse injury. This study reports on pain outcomes in individuals experiencing chronic plantar fasciitis while wearing a shoe with an ultraflexible midsole (Nike Free 5.0) (FREE) versus a conventional training (CON) shoe in a 12-week multielement exercise regimen, and after a 6-month follow-up. Adults with >or= 6-month history of painful heel pain were recruited and randomly assigned to wear 1 of the 2 shoes. All subjects completed the same exercise protocol. A visual analogue scale item tracked peak pain in the preceding 24 hours taken at baseline, 6- and 12-week points, and at the 6-month follow-up. Twenty-one subjects completed the program (9 FREE; 12 CON). Both groups reported significant improvements in pain by the 6-month follow-up, and the FREE group reported an overall reduced level of pain throughout the study as a result of lower mean pain scores at the midpoint and post-test compared with the CON group. The exercise regimen employed in this study appears to reduce pain associated with chronic plantar fasciitis, and in doing so, the Nike 5.0 shoe may result in reductions in pain earlier than conventional running shoes.

The data presented in the study did not support the conclusion made by the authors and this shows how easy it is to jump to conclusions based on just reading the abstract. The data may have actually shown the opposite to the authors conclusion!

When researchers publish their research, they like to publish it in what are called high impact journals. This is a complicated formula based on a number of factors. Due to competition only the best research theoretically makes it into the high impact journals. Because of this, poorer quality research theoretically makes it into the lower impact journals. The Physician and Sports Medicine is a lower impact journal. To publish a randomized controlled trial (like the above one) in a high impact journal, then the reporting almost always has to comply with the CONSORT standards. This is a standard method of analysing and reporting the results of randomized controlled trials agreed to by the editors of many of the high impact medical journals. This allows for a high level of transparency in analysis and reporting. Most of the low impact medical journals also adhere to this standard, but based on the above research, the Physician and Sports Medicine does not appear to.

In the above research, those with plantar fasciitis were given a standard treatment protocol with the only difference being one group kept their conventional running shoes and the other group were given the Nike Free. Their analysis showed non-statistically significant greater initial improvement in the group using the Nike Free (which is problematic conclusion on its own, but I won’t go that way). What the abstract does not say (but the full publication does say) is that the symptoms of two subjects in the Nike Free got so bad that they had to withdraw from the study, so their data was not included in the final analysis. One of the key tenants in the CONSORT statement for the analysis of randomised controlled trials is what is known as ‘intention to treat’ analysis, in that the data from those who withdraw need to be included in the analysis. So the pain scores from the two subjects who got worse in the Nike Free’s who had to withdraw should have been included in the analysis. I am sure you can see if they had done that, the results from the study would have been very different. The results would have probably have been no difference between the two groups or even the Nike Free group doing worse (as two subjects got that bad they had to withdraw!).

I do not know why the Physician and Sports Medicine allowed publication of this study without the ‘intention to treat’ analysis which is the accepted ‘gold standard’. One thing I do know is that this study will find its way into the teaching resources of research methods courses as a classic on how to understand ‘intention to treat’ analysis and why it is important.

I did check around the barefoot running websites and was pleasantly surprised that they were not touting this research as being evidence for minimalist running shoes (or even barefoot running!). Good on them for that. They will certainly be making fools of themselves if they did and providing more evidence of their intellectual dishonesty.

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