Arch height and running shoe prescribing …all is not as it seems?

The prevailing paradigm for a long time for the prescription of running shoes was based on concepts like the amount of “pronation”, the related issue of arch height and foot print analysis. The accumulated evidence, despite the widespread nonsensical writing about “overpronation” (and fueled by a healthy dose of the Dunning-Kruger effect) pointed to this approach probably not being appropriate. Several of the key studies that were done to support this were done by Knapik et al in which they looked at the prescribing of running shoe types based on arch heights using military populations as the participants. They found that selecting running shoes based on arch height did not affect injury rates. They recently published a meta-analysis of their 3 studies that I reviewed here.

These studies seemed to be methodologically sound. This is what they did:

Similar studies were conducted in United States Army (n=2168 men, 951 women), Air Force (n=1955 men, 718 women), and Marine Corps (n=840 men, 571 women) basic training. After foot examinations, recruits were randomized to either an experimental or control group. The experimental group selected or was assigned motion control, stability, or cushioned shoes matching plantar shapes judged to represent low, medium, or high foot arches, respectively. The control group received a stability shoe regardless of plantar shape. Injuries during basic training were determined from outpatient medical records.

…and they found it did not affect injury rates.

Now Paul Ingraham on his blog PainScience has raised what could potentially be a significant issue in the interpretation of these studies. He has this quote from a participant in one of the studies:

I was one of those recruits. I remember wondering why we all got the fancy shoe fitting. When they tossed some boots at me that didn’t fit, I had to trade them with another guy who boots didn’t fit. Out of twelve weeks, we spent most of our physical training in ill-fitting boots. I ran in those boots more than in my fitted running shoes! Throw in a few dozen official and unofficial hikes and the study was probably useless. We mostly wore the shoes for recovery from the hikes, blisters, swollen feet and all.

This now raises an interesting dilemma in the interpretation of the study that Paul discusses.

Did the results the authors got in the study occur because:
1) The prescription of running shoes based on arch height does not really affect injuries
2) The recruits hardly even used the shoes in comparison to the amount of time they used their military boots for during the study, so the running shoes had no opportunity to affect injury rates

There is no reason to give either possible conclusion any more weight than the other. You and I might want to believe (1) as it is consistent with what we want to believe, but given what the participant above said (and it is only one participant), I have to agree with Paul and adjust how much weight I would give to this study in grand scheme of things.

As always: I go where the evidence takes me until convinced otherwise … and while I do believe that running shoe prescription should probably not be based on arch height, these studies do not necessarily support that belief.

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