Muscle strength in shod, minimalist and foot orthotic wearing runners

I going to start off with this image¹:

lookbeforeresearch

There is plenty of the usual propaganda and rhetoric about foot orthotics weakening muscles in the crankosphere blogosphere, therefore they are evil: Truth or lie?

I already addressed the issue of running shoes weakening muscles (they don’t); but that has not stopped the fan boys still claiming that they do. What about foot orthotics? What does the actual evidence or research say?

Firstly, here is a study that one of my Honours student, Mitch Daoud  did a couple of years ago that we won’t be submitting for publication for a reason I will come back to. We recruited three groups of runners: a running shoe wearing group; a running shoe and foot orthotic wearing group; and a barefoot/minimalist group. A number of muscle strength tests were done on them:  hallux and lessor toe plantarflexion strength, ankle inversion and dorsiflexion strength using several trials of a hand held dynamometer; and calf muscle endurance (using a validated measure of heel raises in time with a metronome). With the exception of the last measure, all were normalized to body weight.

Mitch was blinded as to which group the runner was in when doing the muscle strength testing to avoid the potential for any preconceived biases. Here are the results:

mitch

As you can see, the foot orthotic group was the strongest in almost all of the parameters. That surprised even me and was not what we were expecting. The minimalist group does appear to be stronger than the shod group. Even more surprising was the foot orthotic group scored the highest in the calf muscle endurance. I would have thought that the barefoot/minimalist group would have been higher, when it was the lowest! Not the remotest hint of foot orthotics weakening muscles.

Now for the problem and why we are not going to try and publish the data. There were only 4 subjects in the minimalist/barefoot group (and it can’t escape our attention that a lot of fan boys have no problems with a group size of 4 when they see a study they like!). As hard as we tried, we just could not recruit any more in the time frame that is an undergraduate project. Simply, there are just not that many people doing the barefoot/minimalist thing out in the real world compared to their high visibility in social media (minimalist shoe sales have now fallen to around only 3-5% of the running shoe market). The numbers are just not there and I guess we were mislead into believing we could find more due to the prominence of it in social media.

Having said that, the data is worth putting out there in this blog post for people to make of it what they will. It is pretty clear that even though there is only 4 in the minimalist/barefoot group, the orthotic group is stronger, so there are clearly not the remotest hint of a trend towards the foot orthotic group being weaker and the barefoot/minimalsiut group being stronger as the rhetoric and propaganda from the fan boys would have us believe.

Secondly, the data above is also consistent with ALL the other studies on foot orthotics and muscle strength. I just do not get why the fan boys choose to actually ignore what the evidence actually says and just plain make things up when they make their public pronouncements. This is not new evidence; its been around for a while now:

  • Mayer et al (2007) showed an increase in calf muscle strength in the orthotic wearing group. The increase in calf muscle strength in the orthotic wearing group is consistent with the data in our study above; though I am unclear on an actual mechanism.
  • Jung et al (2011) showed an increase in intrinsic muscle strength in the foot orthotic wearing group
  • Our other study (2005) showed no weakness after 4 weeks of foot orthotic use (there was actually a statistically non-significant increase in strength)

These are not cherry picked studies. It is them all. I will update this post the minute any new research on this topic is available, whatever its results. Why do those espousing the rhetoric and propaganda choose to ignore the evidence (hence the image at the top of the post)? Even worse, why do they continue o do it even after the above research is pointed out to them?

As always, I go where the evidence takes me until convinced otherwise, … and I am a slave to the data: Truth or lie? … you be the judge.

1. Thanks to Robert Issacs for sharing the image!

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16 Responses to Muscle strength in shod, minimalist and foot orthotic wearing runners

  1. Kevin A. Kirby, DPM September 9, 2014 at 3:12 pm #

    Great posting, Craig!

    In one of our barefoot running debates, a well-known barefoot running PhD, made the claim that foot orthoses weakened feet. I told her that in my 30 years of seeing thousands of runners feet, both as patients and in running clinics, that I had never seen a runner that habitually wore orthoses have “weak feet”. However, I did say that I had seen plenty of minimalist shoe runners develop stress fractures of their metatarsals who, after walking around in a cam boot for a month, had developed weak feet as a result of them being injured running in their Vibram FiveFinger or other minimalist running shoe, on the advice of one of the self-proclaimed running experts they listened to.

    Like you said, most of the barefoot running “movement” was a virtual trend, many people talking about it on the internet, very few runners actually doing it.

  2. emmbee September 9, 2014 at 6:44 pm #

    I’m interested in maybe what one would call the sociology of the barefoot phenomenon, specifically the belief that running barefoot is evidence of being stronger. It strikes me that this woo belief fundamentally misunderstands what an orthotic does, which as I understand it does *not* prop up the foot, but merely changes the surface against which the foot pushes.

    Wouldn’t it be funny to advertise for orthotics in the way that the barefoot advocates argue for minimalist shoes? A strengthening tool for agile feet that are superior at cushioning over the miles sounds better than “supporting flat feet.” 🙂

    • Craig Payne September 9, 2014 at 6:53 pm #

      Interesting point! I have not thought of it that way, but would never promote a foot orthotic that way as that is not their purpose!

      Barefoot Science orthotics promote them that way:
      http://www.runresearchjunkie.com/barefoot-science/ – with no evidence!
      They also claim on their website that the type of orthotics used in the studies above weaken muscles … go figure!

      Barefoot, foot orthotics, whatever – they just use muscles and load tissues differently; some muscles are typically used less when barefoot running –> they going to be “weaker”

  3. sporks October 19, 2014 at 9:05 pm #

    How big were the other test groups?

    All I see in that table above is error–the error bars are much too large to draw any reasonable conclusions about whether or not the columns and rows correlate. That’s interesting in and of itself, does just as much to disprove the idea you’re attempting to refute. However, it would seem as if saying that the orthotics group was stronger in any category is an incorrect statement.

    • Craig Payne October 19, 2014 at 10:10 pm #

      There was 20 and 23 in the other groups.
      They are not “error bars” but standard deviations.
      I did not report it above, but non-parametric stats showed that the orthotic group was stronger in some tests; I just did not report those numbers due to the numbers in the barefoot/minimalist group.
      So, your claim that my clam is incorrect, is well, incorrect.
      The data is consistent with all the other studies on foot orthotics and muscle strength.

      Given the sample size issue, the data has to be interpreted for what it is. The main conclusions that can be made is that the orthotic group is NOT weaker that other groups and the barefoot/minimalism group is NOT stronger – which is the opposite of what the fan boys keep claiming in the absence of any data to support their claims.

      • sporks October 20, 2014 at 1:03 am #

        I’ll admit that I’m a physical scientist–on plots in scientific papers, standard deviations are often denoted by bars–and these bars are then appropriately named “error bars”. I suppose in situations where there isn’t a true value those terms may be inappropriate.

        Semantics aside, the sentence “ It is pretty clear that even though there is only 4 in the minimalist/barefoot group, the orthotic group is stronger” isn’t supported by the data you’ve presented. Given the size of the standard deviations, there must have been orthotic-users who were weaker than minimalists and vice versa–and the data presented make it look unlikely that the differences were statistically significant–at the very least, that’s not “pretty clear.”

        (of course, the second part of that sentence: “so there are clearly not the remotest hint of a trend towards the foot orthotic group being weaker and the barefoot/minimalsiut group being stronger as the rhetoric and propaganda from the fan boys would have us believe” would actually be supported by the data you’ve posted.

        I’m not trying to call into doubt your conclusions–but be careful about holding a unconscious bias simply because you want to call out the pseudoscience.

  4. dingle October 21, 2014 at 5:44 am #

    A podiatrist who has a website called ‘running barefoot is bad’ – I’m not sure it’s an unconscious bias.

    • Craig Payne October 21, 2014 at 6:19 pm #

      No one was being biased here. The research student doing collecting the data did not know what group the runner was in. The data speaks for itself. Too bad it does not support what you want to believe.

      • sporks October 22, 2014 at 4:07 pm #

        You know absolutely nothing about what I actually believe or want to! There are those among us who are angered by a misuse of statistics even when they support what we think.

        The researcher may not have been biased, but your comments above most certainly were, and were incorrectly drawn from the data given.

        If you’re going to make conclusions based on hazy statistics (such as ” It is pretty clear that even though there is only 4 in the minimalist/barefoot group, the orthotic group is stronger” ), with at most poor-correlations, that’s fine, but it doesn’t jibe with the research high horse this blog is pinned to.

        • dingle October 22, 2014 at 6:56 pm #

          Hear, hear and well put. The trouble is that you can’t teach an old dogma new tricks. Its not a blog for discussion……unless you agree with Paynes point of view.

          • Craig Payne October 22, 2014 at 7:22 pm #

            It sure is difficult when your point of view is repeatedly contradicted by the evidence. It must be difficult coping with that.

        • Craig Payne October 22, 2014 at 7:24 pm #

          Nope. The data speaks for itself.

          • dingle October 23, 2014 at 7:10 pm #

            What point of view is that? Are you making assumptions based on little evidence or just jumping to conclusions…………. pretty much like some of your blog.

  5. Craig Payne October 22, 2014 at 8:25 pm #

    At the end of the day, I presented the above data for what it is.

    As for the orthotic group. The data showed that there was no weakness and maybe an increase in strength. Every single study on foot orthotics and muscle strength have shown the same thing. It does not matter of I may be biased or not; the evidence is totally consistent and ALL showing the exact same thing.
    Its not a matter of agreeing with me or not or if you think I am biased. Its what ALL the studies are showing.
    The fan boys are obviously not happy that the ALL the current evidence is showing this.
    I will be the first to report a study that might show the opposite and be the first to change my mind if the preponderance and strength of evidence shows the opposite to what ALL the current evidence shows.

    As for the minimalist group; yes there was only 4 as that is all we could find as so few people are doing it! But even with that small number there is not remotely close to their being a hint the the minimalist group are stronger and the shod group are weaker. It does not matter of I may be biased or not; the evidence is totally consistent and ALL showing the exact same thing. The Goldmann study showed the traditional running shoe group and the minimalist group both got stronger (no weakening!). No study has shown weakness. then there the other studies showing no increase in arch height with barefoot/minimalism; etc. It does not matter of I may be biased or not; the evidence is consistent.
    Its not a matter of agreeing with me or not or if you think I am biased. Its what ALL the studies are showing.
    The fan boys are obviously not happy that the current evidence is showing this.
    I will be the first to report a study that might show the opposite and be the first to change my mind if the preponderance and strength of evidence shows the opposite to what the current evidence shows.

    • sporks October 23, 2014 at 1:12 am #

      Everything you said above was correct. What one can take from this study is certainly that there is no disadvantage to foot strength in using orthotics–I’m totally on board with the numbers you quoted there supporting the above statement.

      This sort of turned into a mountain from a mole-hill type situation–my only real qualm was when you said the orthotics group was stronger, which I don’t see as being supported by the data you’ve given above–and as someone who often has to read research papers that have phrases akin to “it’s very clear that..” “it’s obvious that..” I take offense when I see one.

      Again, though, you have no idea whether or not I run in a pair of Brooks Beasts or water shoes and regardless, it’s not particularly relevant to my objection.

  6. Josh January 28, 2015 at 2:36 am #

    I’m speaking from personal experience, having worn orthotics for several years and been barefoot for several years.

    The orthotics definitely caused my calf muscles and feet to work a lot harder. They place your foot in a position where the muscles are placed under far greater load due to your legs no longer being able to rely so much on the flexibility of your foot, the orthotics literally reduces the amount your foot can flex which takes load off the tendons in your foot/ankle and transfers it to muscles further up the leg. (the load cant simply disappear it has to go somewhere)

    On this note I don’t see why anyone, even a barefoot enthusiast would be upset by the outcome of this study. In fact I see it has a good thing, its basically saying your lower legs/feet don’t have to work as hard going barefoot, which I have certainly noticed.

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