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Do Foot Orthoses Weaken Feet/Legs?

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Kevin Kirby, Jun 10, 2012.

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    Like many other podiatrists, I am growing tired of the claims from the barefoot/minimalist shoe advocates who continually make unsupported statements that foot orthoses weaken the feet and/or legs. Craig Payne has been particularly vocal in this regard and has pointed out the fact that of the only two published studies that have investigated foot and leg strength after use of foot orthoses, both of them showed an increase in foot and/or leg strength with foot orthoses, not decreased strength.

    Here are the two studies:

    1. Jung DY, Koh EK, Kwon OY: Effect of foot orthoses and short-foot exercise on the cross-sectional area of the abductor hallucis muscle in subjects with pes planus: A randomized controlled trial. J Back Musculoskelet Rehabil, 24(4):225-231, 2011.


    2. Mayer F, Hirshmuller A, Muller S, Schuberth M, Baur H: Effects of short-term treatment strategies over 4 weeks in Achilles tendinopathy. Br J Sports Med, 41 (7):e1-e5, 2007.


    Craig Payne and Gerald Zammit, from LaTrobe University in Melbourne, Australia, also did a study on changes in digital flexor strength which showed no significant change in foot muscle strength after wearing foot orthoses (actually they showed a non-significant increase in foot muscle strength after wearing foot orthoses). This study is currently unpublished.

    In addition, in a recent lecture on barefoot and minimalist shoe running, a very well known researcher on barefoot running compared wearing shoes and/or orthoses to being the equivalent of wearing a "neck brace", showing a photograph of a patient wearing a neck brace to describe how traditional running shoes and foot orthoses somehow weaken the feet. I found this lecturer's mechanical analogy of comparing a foot orthosis or a shoe to a neck brace to be very interesting, but also a very poor mechanical analogy. In fact, this same researcher coauthored a very nicely done research study in 2003 on foot orthosis kinetics and kinematics which compared runners with knee pain running in Root type orthoses to a Blake Inverted orthoses. This study found no change in running kinematics with the more "controlling" Blake Inverted orthoses. Certainly, if foot orthoses did truly "brace the foot" like a neck brace, then the research would have shown a reduction in range of motion of the foot during running, which it did not.

    All the scientific research evidence done over the past half century points to the fact that foot orthoses do not "brace" the foot, but rather they change the magnitudes, temporal patterns and plantar locations of ground reaction forces acting on the plantar foot during weightbearing activities. There is simply no scientific evidence that foot orthoses braces the foot to restrict physiologic motions of the foot. However, there is plenty of research to support the fact that foot orthoses not only are therapeutic but also can decrease pathologic forces and moments acting on the foot and lower extremity that can provide a very valuable therapeutic option for many individuals who, otherwise, without foot orthosis treatment, could very well, over time, develop weakness in their feet and lower extremity due to relative inactivity from their mechanically-based foot and/or lower extremity pain.

    Foot orthoses are not "braces that weaken the feet and legs". Rather, foot orthoses are "high tech foot guidance systems" that guide the foot and lower extremity which, in turn, reduces abnormal and pathologic internal joint forces and moments, improves gait function and heals many painful mechanically-based pathological conditions of the foot and lower extremity.

    We must be vigilant and vocal about these facts as foot health professionals who have taken an oath to ethically treat the feet and lower extremities of the people of our communities. We must speak up loud and speak up frequently about these issues, if, for no other reason, that by accepting the task of protecting the foot health of individuals of our communities we have also accepted the responsibility of preventing our community from being negatively influenced by the misinformation being spread currently by the barefoot and minimalist shoe advocates who insist on misinterpreting research or just plainly making things up that meets their confirmation bias and their agenda.

    If we don't educate the public as to what the scientific evidence shows in this regard, then who will?
  2. Craig Payne

    Craig Payne Moderator

    The increase in strength was not statistically significant, so we reported it as no change. Also the study has been criticized as it was only a 4 week follow up, but i would have thought that if they did actually weaken muscles we would have at least started to see a decrease in strength by 4 weeks if they did weaken them. We did actually follow-up participants as 3 months, but only could get a small number of them to return so did not report the 3 month follow-up data. In those that did return, the muscle strength was still the same as at baseline.

    I mentioned in another thread that I have been looking into the use of "braces" and muscles strength and its hard to find any data. Either there isn't much or I just using the wrong search terms - more often that not, the search query's that I use returns nothing or too many abstracts to manually browse.

    I did find two studies on the use of knee braces in knee OA and they both showed an increase in quadriceps strength!

    I found one study on back braces and muscle activity that the authors made a conclusion that did not appear to be supported by the data - there was no change in EMG activity of the muscles, but they made some sort of nonsensical conclusion about proprioception.

    I was sent one study on the use of ankle braces that showed no changes in EMG activity of the peroneal muscle ---- can we assume if EMG is activity the same, then muscles will not get weaker:
    ....so while I can see the logic behind 'braces' weakening muscles, that is not even what the data is showing (even though I admit, there may be other data that I can not find).
  3. Admin2

    Admin2 Administrator Staff Member

  4. David Wedemeyer

    David Wedemeyer Well-Known Member

    The irony of these studies to a recent thread (closed) with a certain barefoot advocate just makes me all warm and fuzzy inside :rolleyes:
  5. Here is a study that showed an increase in isokinetic quadriceps strength of 16% after wearing an OA knee brace for 12 months.

    Matsuno H, Kadowaki KM, Tsuji H: Generation II knee bracing for severe medial compartment osteoarthritis of the knee. Arch Phys Med Rehabil. 78(7):745-9, 1997.

    Here is a study that demonstrated an increase in hamstring strength after six months of wearing a valgus unloader knee brace.

    Hurley ST, Hatfield Murdock GL, Stanish WD, Hubley-Kozey CL: Is there a dose response for valgus unloader brace usage on knee pain, function, and muscle strength? Arch Phys Med Rehabil. 93(3):496-502, 2012.

  6. CraigT

    CraigT Well-Known Member

    Hi Kevin
    Good summary!
    When I see anyone describing orthoses as 'braces' or 'splints' that stop foot motion then I view it is as a sign that they have a very low level understanding of the mechanics of the feet and foot orthoses.
    .... is a very surprising story!
    Did you use 'this person's' 2003 study this during your debate???

    Now having said this, I have a couple of questions for the floor-
    Is it theoretically possible that a foot orthosis can weaken the foot???

    My personal view is that a well designed foot orthosis shouldn't weaken the foot because it will optimise function.

    An analogy-
    Is a person lifting weights using good technique going to be weaker than a person trying to lift a weight with bad technique and failing??
    Are foot flexors functioning within an optimal functioning zone* going to be weaker than flexors being loaded beyond their physiological capacity??

    I know it is possible to have a negative effect from a foot orthosis... weaken the foot though??? Undecided.

    *made up term describing the fact that a muscle's ability to generate force varies across its ROM combined with mechanical advantage variations that come with different foot morphologies...
  7. efuller

    efuller MVP

    Optimize foot function is term that has been misused and poorly defined. We probably should not use the term after a "because" because unless there are several paragraphs before it describing what foot function is. I agree with the weight lifting analogy though.

    I can see how an orthotic with a medial heel skive or a shoe with a dual density midsole that is firmer medially can make the posterior tibial muscle work less hard. However, if someone is running over a mile, I would maintain that their posterior tibial muscle is getting a workout no matter what they have on their feet. Some feet more than others, but feet are different. But the idea that working out in shoes and or orthotics prevents muscle activity is ludicrous.

  8. OK devil's advocate: lets say we run with and without orthotics and kinematics remain largely unchanged, yet the kinetics do change such that the external supination moment is increased and the internal supination moment is decreased with the orthoses in situ. Sure, the posterior tibial muscle is getting a work-out in both situations, but it's getting a bigger workout without the orthoses (if the posterior tib. is at least in part responsible for the internal supination moment). Assuming, that the posterior tibial is not dysfunctional and functioning within its zone of optimal stress (ZOOS) in both situations, which situation should result in greater strengthening of this muscle?
  9. A foot orthosis may decrease the contractile activity of a muscle which may indeed cause the muscle-tendon unit to be subjected to less tension stress on it during activity. The big question is whether this reduction in muscle-tendon stress is a positive or negative factor for the individual.

    If the muscle-tendon unit is being over-stressed (i.e. near the plastic range of the stress-strain curve), then certainly having a foot orthosis that reduces its activity is in the best interest for the health of the individual. However, realistically, I don't think that this reduction of muscle-tendon stress would cause a "weakness" in the muscle-tendon unit and may, in fact, over time, produce a more strong muscle-tendon unit by allowing greater capacity for muscle work with reduced risk of injury.

    If the muscle-tendon unit, however, is not being over-stressed and is well within the middle of the elastic range and physiologic levels for that muscle, and the foot orthosis reduces the contractile activity of the muscle by, 15% for example, will this 15% reduction in the contractile activity of this one muscle over time be even detectable clinically as a weakness in the muscle or cause any functional incapacity? I don't think so. There is a big difference between being within the normal ranges of muscle strength for an individual and having "muscle weakness".

    The term "muscle weakness" means that the muscle strength is below a normal range of strength values for a certain group of individuals of a certain sex and age. "Muscle weakness" does not mean that the person went from being from in the upper 33% of normal muscle strength to the middle 33% of normal muscle strength.

    Therefore, for the barefoot and minimalist shoe advocates to continue to claim that foot orthoses "weaken feet" is: 1) not supported by any scientific evidence, and 2) not a physiologically realistic scenario that would be expected to occur in an individual that can perform their daily activities without gait or functional abnormalities or pain during these activities.

    Simply put, the curious suggestion by the barefoot and minimalist shoe advocates that foot orthoses somehow weaken feet is neither physiologically nor biomechanically coherent and not supported by a shred of scientific evidence. In my opinion, those individuals that make these types of unsupported statements show how little they understand about the biomechanical nature of foot orthoses and the complex physiology of the human neuromuscular system.
  10. Unfortunately, I have heard this individual make these "shoes and foot orthotics are like neck braces" claims before. Didn't have time to bring up the 2003 study but was able to point out that the cost of my orthoses was much less than the cost of their "gait retraining program" which was quoted as costing $640.00 for eight sessions.

    When I pointed out that their $640.00 gait retraining sessions was more costly to the patient than their complaints about my "$400.00 foot orthotics".....I got a big laugh from the audience.:drinks
  11. phil

    phil Active Member

    I'm guessing this was your debate with Irene Davis at the sports medicine meeting?
  12. Quasar

    Quasar Member

    Howdy, Kevin,

    All of your replies (and those of all other respondents) bemoan the difficulty of educating the public and (sadly) the medical profession at large about foot mechanics and, perhaps with much greater difficulty, bringing acceptance and action on our experience.

    I am particularly disappointed with my results since early on in practice of bringing acceptance to the fact that podiatry is of premier importance in pediatrics. The idea that foot problems are primarily those of youth and not of old age has been and, I'm sure, still is at best hard to swallow by the public and medical community alike. They continue to take symptoms as problems. Mert Root had repeatedly discussed this phenomenon. At one point he told us that his practice had been 75% pediatric.

    Prevention, prevention, prevention!!!

    After all, how can Bill Orien's "magic shovels" be anything other than the venerable arch support!! (BTW, anyone know how Bill is? I've heard nothing of him for decades.)

    Regards to all...including those from Down Under who still amaze me by their standing on their heads!!


  13. Kevin, I tend to agree, but I think the changes observed in EMG patterns with orthosis in-situ, and the hypothetical I provided above should provide a potential mechanism for weakening of muscles in association with foot orthoses which is both physiologically and biomechanically coherent.

    Unless, the foot orthosis don't change the peak stress magnitude within the muscle units, but rather the timing of these... Or indeed, increase the magnitude of stress within certain muscles (which will result in an increase in strength).



    Attached Files:

  14. Yep. Evidence, evidence, evidence???
  15. drsha

    drsha Banned

    1. When you state "like many other podiatrists", how many DPM's do you think you represent?

    You certainly don't represent me and many others that I come in contact with in America.

    2. When you state "All the scientific research evidence done over the past half century points to the fact that foot orthoses do not "brace" the foot, but rather they change the magnitudes, temporal patterns and plantar locations of ground reaction forces acting on the plantar foot during weightbearing activities, not that I disagree but just how much scientific research evidence is there?

    3. As an EBM advocate, like you, I find the evidence that you present to be rather weak, one sided (your side), personally selected and overrated.
    IMHO, it does not override or trump the expert opinions and experiential clinical successes that live with a differing take on this and many other subjects that you wish to control.
    If you had any more or stronger evidence, we would all know about it.

    What do you think of the work of Dr. Munson and the US Army countering your claims to some extent?

    3. Strengthening the plantarflexion power of the triceps, for me, means that primary muscles are in fact weakening or becoming inhibited and an equinus pathology is being promoted.
    Summarily, this goes against your argument because important muscles are being disused that forces the t. Achilles to compensate.

    4. Citing stronger digital flexors, once again, reflects a compensatory weakness of the first ray rocker necessitating compensating activity in the 2-3-4-5 rockers, which to me is pathological.
    This goes against your argument.

    5. Combining therapies (Orthotics +) without controls doesn't prove that it was the orthotics that was the positive entity.
    Level II evidence at best.

    6.Picking one or two muscles, randomly to test (abductor hallucis? there's an important muscle in running).
    Why weren't more tested in these studies?

    7.Where is your evidence involving P. Longus, P. tibial, A tibial, FHL, etc?
    These muscles, if strengthened by orthotics with study, would mean something for me.

    Taking all the anecdotal, expert experience and clinical successes of increasing numbers of practitioners and sending them under the bus with the short term, small patient numbered, poorly conceived evidence you site is simply unfair and not a valid argument IMHO.

    and, most importantly,

    without defining "The Orthotic" and then extrapolating that to mean "orthotics" produces more than enough error in these studies and has no meaning when it is applied to "all orthotics" being fabricated and dispensed to the foot suffering public.
    Whose orthotics, what orthotics.
    Please give us your definition of an "Orthotic" for research purposes.

    Patients, for years and years, coming to me with "orthotics" that have failed to correct a diagnosis of "overpronation", (whether they are "overpronated" or not), test poorly for P. longus power and motor control.
    Additionally, these same patients, when tested barefoot and upon their "Orthotics" almost always exhibit poorer 1st ray function in their orthotics rather when compared to barefoot (the devices are applying a supination moment to the 1st metatarsal) making them potentially harmful.

    IMHO, accepting the pittance of evidence that you refer to over and over as a reason to make your expert opinions more important than those differing with them is using EBM as a battering ram against those with opposing views unfairly.

  16. DaVinci

    DaVinci Well-Known Member

    So, Dennis, we have 3 studies that you don't like all saying the same thing and no study showing the opposite, so you go into a silly rant because it happened to be Kevin who started the thread.

    You claim to be a proponent of evidence based medicine, yet anyone can go back and read everything that you have written on functional foot typing and neoteric biomechanics and that you don't have a shred of evidence for it. You comment above that Paynies study is irrelevant because its not published. As your FFT is not published in a peer reviewed journal, then that also makes it irrelevant. You can't have it both ways.

    I think the evidence is clear. There are 3 studies, and yes they have some issues with them, but they are all saying the same thing. Dennis, you have no studies to back up what you are saying. You loose.
  17. I want to enthusiastically nominate this quote from DaVinci as quote of the year for 2012. Classic!!
  18. toomoon

    toomoon Well-Known Member

    gets my vote!
  19. drsha

    drsha Banned


    But the real question here as to your apparent contest whose rukes you control and define, what do I loose? The entire battle?

    Does the evidence of these two weak studies give you the winning hand in the argument?

    If you have weak and flawed evidence and I have no evidence then the bulk of the argument lives on anecdote, opinion, clinical experience and success rates in practice.

    DaVinci, are these two weak and flawed studies valuable, important, worthy of the extrapolation that it serves as valid EBM as per Sackett's definition to control the argument.


    If the evidence were so available and applicable, why would Craig and others be scrambling to define "What to do when there is no evidence"?
  20. drsha

    drsha Banned

    I guess that's better than responding to the fact that your two studies are weak and flawed.

  21. drsha

    drsha Banned

    I want to enthusiastically nominate this quote from Dennis as quote of the year for 2012. Classic

    Dr Sha
  22. SarahR

    SarahR Active Member

    I'm sick of hearing it too. Even the guys and gals doing the fitting at some SHOE STORES try to get me to cast off my own orthotics! I'll ask them if they realize you're talking to the person who Rx'd them too? And they've NEVER lived in my feet, so how can they know that "strengthening your muscles better"?

    WHAT are they saying to my patients???

    Seriously. If you want to remain in pain, give up the orthotics and try and continue with any level of activity that will result in muscle strength improvement around that problem joint/structure. Try. I can poke you with a cattle prod while we're at it; pain is negative reinforcement and a major barrier to a healthy active lifestyle. :bang:
  23. NewsBot

    NewsBot The Admin that posts the news.

    Not foot orthotics, but:

    Can lumbosacral orthoses cause trunk muscle weakness? A systematic review of literature.
    Azadinia F, Takamjani EE, Kamyab M, Parnianpour M, Cholewicki J, Maroufi N
    Spine J. 2016 Dec 14. pii: S1529-9430(16)31130-5. doi: 10.1016/j.spinee.2016.12.005.
  24. Craig Payne

    Craig Payne Moderator


    Attached Files:

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  25. scotfoot

    scotfoot Well-Known Member

    I have never understood how arch supports can weaken the intrinsic toe flexor muscles since these become active at heel off and medial arch supports no longer support anything at this point.

    This recent paper seems to point to arch supports actually acting to strengthen the feet of young footballers with flatter than normal feet.

    A 9-week arch supporter intervention may promote the development of the ABH and FDL CSA in young flat-footed soccer players."
    Effects of a 9-week arch support intervention on foot morphology in young soccer players: A crossover study
    Kohei Hikawa, Toshiharu Tsutsui, Takehiro Ueyama, jin Yang, Yukina Hara, and 1 more
    This is a preprint; it has not been peer reviewed by a journal.
    This work is licensed under a CC BY 4.0 License

    A flat foot is a common cause of chronic sports injuries and therefore many opportunities for arch support interventions exist. However, no longitudinal studies have been conducted on the effects of arch support intervention on flat-footed young athletes that also take into account the developmental effects. This study aimed to determine the management and prevention methods for flat foot by performing a 9-week arch support intervention on the foot morphology and cross-sectional area of the foot muscles in flat-footed young athletes.

    Thirty-one elementary school boys with a decreased medial longitudinal arch in the foot posture index were selected as participants from a local soccer club and randomly divided into two groups. In one group, in the intervention period, an existing arch supporter was used to provide arch support, while in the other group, no special intervention was provided in the observation period. To account for developmental effects, the intervention study was conducted as an 18-week crossover study in which the intervention and observational phases were switched at 9 weeks after the intervention. Foot morphology was assessed using a three-dimensional foot measuring machine, and the cross-sectional area (CSA) of the internal and external muscles of the foot was assessed using an ultrasound imaging device. We examined the effect of the intervention by comparing the amount of change in the measurement results between the intervention and observation periods using corresponding t-tests and other methods.

    After adapting the exclusion criteria, 14 patients (28 feet) were included in the final analysis. The CSA of the abductor hallucis muscle (ABH) increased 9.7% during the intervention period and 3.0% during the observation period (p = 0.01). The CSA of the flexor digitorum longus muscle(FDL)increased 7.7% during the intervention period and 4.2% during the observation period (p=0.02).
    A 9-week arch supporter intervention may promote the development of the ABH and FDL CSA in young flat-footed soccer players.

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