Do foot orthotics interfere with the arch dynamics

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The Foots Arch and the Energetics of Human Locomotion
Sarah M. Stearne, Kirsty A. McDonald, Jacqueline A. Alderson, Ian North, Charles E. Oxnard & Jonas Rubenson
Scientific Reports 6, Article number: 19403 (2016) (full text)

 

Can't see where the authors of this study controlled for shoe/orthotic mass between conditions. Just the act of adding an orthosis of any kind to a shoe will increase the mass being carried on the foot and therefore will increase metabolic cost of running, regardless of the "spring in the arch of the foot". This lack of control for mass being worn on the foot appears to be a fatal flaw of this study.

 

Also, even if the results are valid, the should have concluded that "foot orthotics with the design features used in this study got the results it did"...they can not be extrapolated to other foot orthotic design features. I could see big differences between orthotics with more arch fill vs less (ie the Sole Supports MASS type designs) in this type of study.

 

Another way to spin this article, which the authors failed to mention, was to state that by reducing the loading forces on the plantar ligaments, plantar fascia, etc, by reducing navicular drop, the foot orthoses would have reduced ligament/fascia strain/stress which could not only heal injuries to these structures but also prevent injuries to these structures in the future.

My opinion is that these authors needed to have someone else review their article so their blanket statement suggesting foot orthoses somehow are not "energy efficient" for runners could have been countered by arguments that stated that it may not always to be beneficial to use the "end range of motion" of foot joints and that foot orthoses, for many runners, may do more good than harm.

 

My bad. The authors did control for shoe/orthotic mass. For some reason, the materials and methods section is stuck at the end of the article and I missed it on the first pass.

I do find it interesting that these comments from the authors are listed in the "supplemental section" of the paper. They really should be in the discussion, not in a "supplement" to the paper.

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Dear Kevin and Craig,

Thanks for your interest in the paper. I noticed your comments when I was searching for a related thread on this paper.

You are correct that shoe mass will have an effect on running energetics, that restricting arch compression can, in some cases, be a beneficial way to offload tissues and reduce injury, and that our results do not necessarily extrapolate to other orthotic designs.

Kevin, I think you already noticed that we did control for shoe mass.

Craig, You may not have seen this statement: "The authors would like to note that the foot insoles used in this study do not represent conventional prescription practices by health practitioners for symptomatic individuals in a clinical setting, but rather a tool for experimentally testing our hypotheses.

Our interests were not in footwear or orthotic design per se but rather in the mechanical and energetic function of the arch of the foot. We do not claim that orthotics or arch support are good or bad, or when they should or should not be used. This is better done by clinical experts such as podiatrists.

We do feel, however, that the finding that restricting arch compression affects running energetics is relevant to footwear and orthotic design. Whether it will be an important factor will depend on the specific footwear/orthotic, it's intended use, and the person for whom it is designed. I don't think we make any blanket statements anywhere that all foot orthoses are 'not energy efficient'. But we can't control how the media interprets and reflect our findings.

As for the 'limitations' section being in the supplementary material- it is becoming more common to place more material in supplements and often a request of reviews and editors to shorten the main paper.

I'm glad you found the paper interesting.

Best Regards,

Jonas

--
Jonas Rubenson, Ph.D.
Associate Professor of Kinesiology and Physiology
Muscle Function & Locomotion Lab and Biomechanics Lab
Pennsylvania State University
29 Recreation Building
University Park, PA, 16802
Tel: + 1 814 867 6209
Fax: + 1 814 863 4755
Email: jonas@psu.edu

 

Jonas; thanks for stopping by!

My issue with all foot orthotic studies is the extrapolation of the results beyond the design features and/or the prescription protocol used for the foot orthotics in the study.

Some orthotics will use more heel wedging and a lowered arch profile and not conform to the arch; others will be be conforming to the arch profile --> I can see just those variation giving different results in a study like the design you did. ..... and even then, with the arch conforming type designs, materials choices and different thickness of materials will have different potential "energy returns" --> theoretically the same shape orthotic with different material properties may help or hinder the "arch energy return properties"

 

Hi Craig,

Sure, I agree. I don't think we generalize though. And I would not classify this as an 'orthotic study'. The insole we used was a tool to explore the basic mechanical function of the foot and has specific qualities that you wouldn't see in any orthotic prescribed to anyone.

What we are arguing is that if the arch compression is restricted energy cost of running can increase. As you point out, that is not the case in all orthotics/shoes. Or if the orthotic had some very good spring qualities to it it could also provide elastic energy return and improve running economy. We designed ours specifically to not return elastic energy.

We are not challenging the merits of foot orthoses or arch support. They are important! We examine the structure-function relationship of the musculoskeletal system. If our findings filter into more clinical areas such as yours and if they provide some insight into foot function than we are glad for that. But it is not our specific intention or interest to impact the design or orthoses.

All the best,

JOnas

 

Thanks; I can appreciate that.
But, there is a certain group of people out there that will pick up on this as being a reason not to use foot orthotics and openly promote that view.
I have set up a few social media alerts to see what comments get made!

 

Thanks Craig,

I'd be interested to see the social media response. I've followed a few twitter threads and there are some comments to that effect. We don't promote that view. One of our authors is in fact a professional podiatrist and of course prescribes orthoses regularly. In discussions with media we try to be clear about this up-front.

All the best,
Jonas

 

Jonas:

Thanks for stopping by Podiatry Arena.:welcome: It is always good to hear about papers we are discussing straight from one of the authors. I appreciate your comments.

After reading the "supplement" to your paper, that I just so happened to find by doing more digging through the files, I can see that most of my concerns about your study were addressed. Just wish some of those concerns were listed in the discussion of the paper as has been the standard of publication for the past thirty years, as far as I have seen. In addition, since when do scientific journals list their "material and methods" section of the papers they publish after the discussion of the paper? This is how I missed where you controlled for shoe mass.

I agree with Craig that when I read the discussion of your paper, it seems to lean toward the notion that foot orthoses for running may involve more metabolic cost and therefore, foot orthoses should be avoided for runners. I know of very few podiatrists, if any, who recommend foot orthoses for runners to increase their metabolic efficiency during running. Most podiatrists generally recommend foot orthoses to treat injuries and prevent new injuries, not to improve metabolic efficiency. In fact, for most of my serious runner patients, I have them remove their orthoses from their racing flats to decrease the mass on the foot to improve racing performance by, hopefully, increasing their metabolic efficiency during running.

Finally, Jonas, seeing that you are from Penn State, please say hi to Neil Sharkey and Steve Piazza for me. It's been over 11 years since I last visited Penn State when I was helping Steve and Greg Lewis with some cadaver foot research. Neil and I were at UC Davis together when we both had much more hair.

 

Hi Kevin,

Yes- will say hi to Neil and Steve! I see Steve regularly and collaborate on some new projects.

I appreciate your concerns and agree fully that orthoses are an important prescription for preventing/treating injury. In the discussion section we indicate that certain foot orthoses might influence energy cost if they restrict arch compression significantly. We don't argue that orthoses should always be avoided in running or suggest that they should be used to alter running efficiency. We hope that it does not get interpreted this way. But we felt that the finding is relevant to orthotic design; knowing that a specific orthotic might influence energy cost can be important and we're putting the information out there. Whether someone should/should not use a foot orthosis running is highly individual and a decision that the individual should make with their podiatrist/clinician.

All the best,

Jonas

 

p.s. It's becoming more common for journals to place the Methods section at the end. Personally I am with you and generally prefer the more traditional order of Methods before Results and Discussion.

 

Jonas:

Thanks for your reply. Good to hear of your views.

I think your paper will certainly promote some good discussion on foot orthosis design, which is a topic I do write and lecture on quite frequently. I think practically, though, that the metabolic efficiency of running is of little concern to the injured runner. Injured runners or runners wanting to prevent injuries are the patients I see (and most sports podiatrists see) that want orthoses for their running. I don't think I've ever had a runner come into my office in my over three decades of practice wanting foot orthoses to improve the metabolic efficiency of their running.

Possibly the higher arched orthoses could have an effect on running efficiency as your research showed. However, if a runner ever asked me how to best improve their running efficiency I would likely tell them to 1) wear the lightest running shoe with a thin cushioned sole that won't cause them an injury, 2) don't wear foot orthoses, and 3) to lose some weight (i.e. reduce the fat percentage of their body and don't add extra muscle in their upper body)!!

 

I wonder how much of the reduction in spring of the arch came from the device and how much came from the increase in plantar muscle action due to the device being used ( as research has showed )

I guess it doesn?t really matter except will strengthening the plantar intrinsic muscles also lead to a change in the arch spring and therefore less efficient running ?

 

I appreciate that the present study was focused more on running, but I'll just throw this into the mix: http://www.oandplibrary.org/poi/pdf/1988_02_073.pdf