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Foot function and low back pain

Discussion in 'Biomechanics, Sports and Foot orthoses' started by NewsBot, Sep 29, 2007.

  1. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
    1

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    A single-blind pilot study to determine risk and association between navicular drop, calcaneal eversion, and low back pain.
    Brantingham JW, Adams KJ, Cooley JR, Globe D, Globe G.
    J Manipulative Physiol Ther. 2007 Jun;30(5):380-5.
     
  2. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    ....so why was it even accepted for publication?
     
  3. Admin2

    Admin2 Administrator Staff Member

  4. admin

    admin Administrator Staff Member

    Bilateral and unilateral increases in calcaneal eversion affect pelvic alignment in standing position.
    Pinto RZ, Souza TR, Trede RG, Kirkwood RN, Figueiredo EM, Fonseca ST.
    Man Ther. 2007 Sep 29; [Epub ahead of print]
     
  5. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
    1
    There was also this from January:
    Effect of feet hyperpronation on pelvic alignment in a standing position.Khamis S, Yizhar Z.
    Gait Posture. 2007 Jan;25(1):127-34
     
  6. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
    1
    Spinal Biomechanics: What Role Do the Feet Play?
    Kim D. Christensen,
    Dynamic Chiropractic November 19, 2007, Volume 25, Issue 24
    Full article
     
  7. Bruce Williams

    Bruce Williams Well-Known Member


    As usual Craig, thanks for the biggest laugh out loud of the day!!!:D


    :drinks
    Bruce
     
  8. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
    1
    Positional relationship between leg rotation and lumbar spine during quiet standing.
    Parker N, Greenhalgh A, Chockalingam N, Dangerfield PH.
    Stud Health Technol Inform. 2008;140:231-9.
     
  9. Some good Data here. But a long way from indicating the kinematic chain theory can be relied upon to treat LBP.

    Firstly a correlation between LBP and foot posture does not indicate a causal link in either direction!

    Also i think we must be aware of the perils of over extrapolation. Placing an eversion wedge under the foot may well affect a rotational change in the leg, however the foot in relaxed stance will already be at maximum passive pronation in most cases. What would be more interesting would be to put the same wedge to invert the foot and compare the difference THAT makes.

    I'm not saying there is not a link between foot posture and LBP mind you. I just feel that the evidence we have to support the kinetic chain model is flawed and the evidence for the kinematic chain even more so!

    Why have these studies worked with either demographic data (which may establish correlation but not causality) and induced hyperpronation? Given the point of these studies is to consider the relevance of insole why simply compare relaxed stance spinal / pelvic position with the position wearing insoles?

    I beleive that insoles can have a positive effect on LBP but i think we need a better understanding of why and induceing hyperpronation to indicate the kinematic chain smacks of a study designed to prove the hypothesis rather than to disprove it to me.

    Regards
    Robert
     
  10. GavinJohnston

    GavinJohnston Member

    Is motion control a dirty word in podiatry? It seems motion control has been sold to the physio world without any evidence.... Im sure Ive seen changes in the clinic in regards to lower limb int/ext rotation with fairly basic orthotics. Was I imagining this???
     
  11. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    Off course it has. Motion dosen't hurt. Forces hurt. Its all about force contral and not motion control (see this thread, among many others - esp pages 2 & 3).
     
  12. GavinJohnston

    GavinJohnston Member

    Dear Craig thanks for the rapid reply.
    The shift of asessment as stated by Kevin Kirby in that forum is obviosly abour kinematics. Its great to be able to access leading health professionals brains , Im not aware of an equivalent site for physios.
    I know this topic has been thrashed to bits but I would like to put my 2c in.Maybe an opinion from a manual therapist may be of interest.If no one replies Ill assume I need to do much more reading....
    Kevin States
    "Simon has very nicely provided an analysis of the tissue stress theory of mechanical foot therapy. The key points of the tissue stress theory of mechanical foot therapy is that the clinician should first identify the anatomical structure that is the cause of the pain/pathology, then determine the structural/functional factors that are the cause of the pain/pathology, and finally design a treatment plan that will reduce the pathological stresses on the injured tissue and will improve gait dynamics, without causing other injuries/symptoms.

    One cannot separate kinetics from kinematics in biomechanics. Changes in kinetics cause a change in kinematic function. Therefore, if one identifies a change in kinematic function, then one also knows that the kinetics has changed. However, if there is no change in kinematic function, one can not also presume that there is no change in kinetics, since, as Simon notes, the internal forces and internal moments may have changed with no apparent change in joint position."

    Im a myofascial therapist and we are always trying to normalise muscle function by needling or releasing muscles that have fibrosed due to mechanical strain. Commonly the lateral fascial line gets locked short/ tight and weak with pronated feet (TFL,ITB,PeL,PeB etc) THis serves to inhibbit FHL,TPost,etc. The latter being in a mechanically weaker position.I was taught that a muscles optimal output and therefore its most efficient function is halfway from its maximally lengthened position and its shortest position. This position being "ideal posture".
    It was my understanding that an orthotic put the foot into this position. Clinically attention to the muscles above mentioned changed a persons posture (kinetics)in combination with orthotic therapy.
    This muscle balance theory is the cornerstone to myofascial therapy which can be applied to all joints of the body,and we expect visual changes????
    Regards Gavin J
     
  13. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    There are a couple around (eg PhysioBob) and I occasionaly check them out, but they never really get into some topics like we do here (every forum has its "characteristics")
    Never heard any evidence to support that and I fail to see how it can be true - every muscle would have to be different depending on its relationship to the axes of the joint that it crosses, I would have thought.
    We use to think thats what we were trying to achieve, but the evidence is pretty clear that this does not happen (and when it does happen, its not correlated to clinical outcomes).
     

  14. Gavin:

    Good to have you join in on our discussions. Even though foot orthoses may or may not noticeably change the position of the osseous structures of the foot, they may still have a therapeutic effect. Sometimes I see rather large changes in gait kinematics with foot orthoses, and other times I see minimal to no change in gait kinematics with foot orthoses in my patients. Certainly there is plenty of scientific research that clearly shows that foot orthoses changes gait kinematics, both in running and walking. However, the research also shows that the changes in kinematics are much less than the changes in kinetics.

    It would be difficult to say that foot orthoses by themselves "change posture" unless that means "foot posture" specifically. I do see in my clinic, however, that foot orthoses may dramatically change the angle and base of gait, the stride length, the length of the propulsive phase of gait and the position of the ankle, subtalar and midtarsal joints during both the stance and swing phases of walking gait.

    In regards to changes in muscle moment arms, foot orthoses may also signficantly affect these. For example, in the case of the subtalar joint (STJ), if the orthosis moves a foot from the maximally pronated to a less pronated STJ position, both the anterior tibial and posterior tibial muscles will have increased supination moment arm lengths relative to the STJ axis than they would have had without the foot orthosis intervention.

    Even though these changes in muscle moment arm lengths do occur sometimes due to a change in joint position with foot orthoses, the major mechanical effect of foot orthoses on the human body is rather to change the point of application, magnitude and temporal patterns of ground reaction forces acting on the plantar foot during weightbearing activities. This is the change in kinetics that is so important in producing the internal mechanical effects on the structural components of the foot and lower extremity that cause not only the change in kinematics we may or may not see, but also the change in subjective complaints that we very commonly see with foot orthoses.

    Good to have you contributing and hope this helps.
     
  15. David Wedemeyer

    David Wedemeyer Well-Known Member

    This is interesting to me because I do know one of the authors of this study, Dr. Gary Globe. He headed our clinic at Cleveland Chiropractic College when I was an intern and I do not recall assessment of the feet or gait analysis being a part of the clinical analysis or requirement of our clinical experience. I am interested in who funded that study and when they adopted an interest in the lower extremity, which was severely, absent during my clinic rounds.

    I do understand the relevance of an inquiry into the relationship between hyperpronation and the prevalence of mechanical low back pain. The premise of this study is to assess if there is causal link between patients with flatfoot based on calcaneal eversion and measurable navicular drop and that pathological pronation is a contributing factor in mechanical LBP.

    I know that Foot Levelers has marketed its product to my profession based on an assumption that there is a causal link between foot position and changes further up the kinetic chain. Their entire paradigm is built upon their assertion that even asymptomatic patients require “spinal pelvic stabilizers” to optimize the relationship between the lower extremity and the spine to "stabilize the feet/lower extremity/spine" yadda yadda. What a convenient way to market orthotics to a broad spectrum of patients! I am completely unaware of any research that supports their claims and you are left trying to accomplish this with expensive, proprietary, ‘customized’ accommodative inserts made of one choice of material; EVA.

    While I personally believe that there may be a link confirming this relationship in some of our patients, I would like to see more independent, well-designed RCT’s to affirm this. I notice that Dr. Christensen, who I have a great deal of respect for has listed Dr. Rothbart in his references, which raises an eyebrow and makes me question the credibility of that article.

    Kevin Kirby wrote:

    It would be difficult to say that foot orthoses by themselves "change posture" unless that means "foot posture" specifically. I do see in my clinic, however, that foot orthoses may dramatically change the angle and base of gait, the stride length, the length of the propulsive phase of gait and the position of the ankle, subtalar and midtarsal joints during both the stance and swing phases of walking gait.

    Even though these changes in muscle moment arm lengths do occur sometimes due to a change in joint position with foot orthoses, the major mechanical effect of foot orthoses on the human body is rather to change the point of application, magnitude and temporal patterns of ground reaction forces acting on the plantar foot during weightbearing activities. This is the change in kinetics that is so important in producing the internal mechanical effects on the structural components of the foot and lower extremity that cause not only the change in kinematics we may or may not see, but also the change in subjective complaints that we very commonly see with foot orthoses.

    I couldn't agree more with these statements by Kevin. After treating many patients over the years with both Chiropractic Manipulation for mechanical low back pain and foot orthoses, I cannot say with any real certainty that their orthoses are directly responsible for a reduction of low back symptoms (with one caveat; rigid cavus feet where the goal of orthotic therapy is to reduce heel strike forces via accommodation with softer materials).

    If there is a link between flatfoot conditions, calcaneal eversion, navicular drop:bash: and mechanical low back pain I would like to see it proven and reproduced in RTC's. I feel that too many musculoskeletal practitioners espouse this link in order to justify affording a wider number of patient orthotics which are meant to address “postural distorsions" if you will and not specifically kinetic chain posture and kinematics, which is more global. Podiatrists have typically chosen orthoses as a conservative method to address pathology and symptoms of the feet and lower kinetic chain, which is a medically necessary pursuit and makes good clinical sense. Ancillary providers appear to have invaded the Podiatric turf and adopted a new lexicon to further their own goals :confused:

    I was recently contacted by one of the Chiropractic publications to ask if I would participate in a survey of orthotic products we are using in practice. I think that they were surprised by my answers and approach because I flat out told them that I do not provide orthoses for low back pain (excepting the rigid cavus foot type) and do not adhere to one product, lab or material. They were also surprised that my orthosis business is built on referral from medical providers for medically necessary devices and seemed interested in learning more. I got the feeling that they were unaware what a Certified Pedorthist is and what their role in health care is.

    One day and one mind at a a time...:boxing:

    Foot orthoses for LBP is a recurrent theme in many Chiropractic and Physical Therapy clinics but I haven't read any research strongly favoring this paradigm, can anyone reading this share this material if it is available?
     
  16. Admin2

    Admin2 Administrator Staff Member

    See these threads:
    Claims that shoe insoles relieve back pain are unsupported
    Insoles for prevention and treatment of back pain
    RCT of custom foot orthoses and low back pain
    Other threads tagged with low back pain
    Other threads tagged with proximal problems
     
  17. David Wedemeyer

    David Wedemeyer Well-Known Member

    Craig thank you for the links.

    I was actually being somewhat facetious. I am still waiting for the glittering epiphany from the companies who sell these ideas that insoles/orthoses can predictably and reliably negate mechanical low back pain due to overpronation (whatever that is). :eek:

    I would also like to see them validate them for posture, proprioception and a receding hairline as well. They may even improve your sex life, who knows?

    We should patent the "Little Blue Insoles" while we are at it :cool:.
     
  18. GavinJohnston

    GavinJohnston Member

    Dear Kevin Craig and David,
    What a cool use of the world wide web, Im very greatful for the opportunity to chew the fat with leaders in such an interesting field.
    Inreply to Craig I have dug out my very first biomechanics manual (1991) to explain my reasoning behind optimal muscle strength....I can see you roll your eyebrows now.......
    "The force length curve for one sarcomere has been established"...Max isometric contraction on y axis and sarcomere length on the x axis with a bell curve type shape
    " The amount of effective overlap between the actin and myosin filaments is related to the maximum strength of contraction"
    I figure this means a really short or long muscle is not as strong.
    Thats why I figured if you keep muscles in this position they had optimal output.
    There is similar work done on the TMJ in Dentistry.
    TO Kevin
    has there been any studies able to measure hip Int Rotn/ Ext Rotation with and without orthotics? I wear orthotics to stop my piriformis from playing up and I thought it was because of this control. Also how do you measure kinematic changes in the clinic??
    To David
    The invasion of other healthcare professionals into the podiatrists domain of orthotic prescription was in Australia led by podiatrist owned companies. The invasion of therapists modalities has occured in all professions ....massage, dry needling, electro therapeutic agents,exercise prescription manipulation etc is not owned by any one profession anymore. Im sure this has many positive and negative effects but hopefully the sharing of ideas will in the long run benefit everybody.
    Multi disiplinary approaches in my opinion is the best form of chronic pain Mx, as is the case in many clinics around Australia.

    Thans for considering my blurb on such an interesting topic.
    Regards
    Gavin Johnston
     
  19. :good:

    No. We all know that they increase fertility right? And i can show strong anecdotal evidence of the deleterious effect babies have on your sex life.

    I think the distinction between kinematic and kinetic change is important. I cannot remember the references but i'm pretty sure i remember that most studies show fairly minimal changes in leg rotation associated with use of orthotics.

    Also need to be aware of the "spikeorthotic" element. Put something unfamilier in somebodies shoes and tell them its for posture and it is not surprising their posture changes.

    I could show you a website with some dreadfully good before / after animations!

    The problem with THAT is that its far harder to assess kinetic changes than kinematic changes and that makes it hard to know exactly what effect we are having. It is easy to reason a ratianale for how it might work, however LBP is a complex multifactoral condition including many psychosocial aspects and as such, responds rather well to a good placebo.

    This, though it may seem unpaletable, is another explanation for the success of orthotics in LBP. Not saying it is mind you, just saying it would be another explanation for a pretty solid success rate.

    Cue the Angry Mob.:butcher:


    Robert
     
  20. Don't know of any orthosis studies that measure hip motion. However, that doesn't mean that they don't have a mechanical effect. We simply don't know the answer to that one. I estimate kinematic changes in the clinic visually.
     
  21. Better be careful there, Robert. I have trademarked and patented the term "spikeorthotic" and anyone that uses this term again, without my express written permission, will be punished!!! (.....by being made to walk in a Sole Support super high arched insole on one foot and a Rothbart Proprioceptive insole on the other foot!) :pigs::rolleyes::pigs:
     
  22. http://www.oandp.org/jpo/library/2004_03_087.asp
     

  23. Come now, thats just being nasty!

    You're right though. Credit where its due;).

    Regards
    Robert

    The "spikeorthotic brand and all subsideries, associates, versions, copies and rip offs remain the intellectual property of Prof K Kirby. No claim is made to ownership of this idea, nor is any right to manufacture said device inferred or claimed. The application of a drawing pin under the arch is not recommended without first understanding "ascending flinching patterns" training for which is available from prof Kirby's training company run by his associates "Fleece, Cripple and Sneer". For details of the spikeorthotic please send a SAE with a cheque for £300 to Kirby's Urinary Extraction Dept located in Cuba. The company does not indemnify you against loss of earnings, litigation or complaints arising from placing something pointy under somebodies foot and besides, its not like they can run after you is it!
     
  24. Dananberg

    Dananberg Active Member

    Foot function and lower back pain can be very related, but one needs to think sagittally to see the connection. The papers below are for reference purposes,with the 2nd describing an almost 50% increase (7.5 to 13 degree average increase in hip joint extension during single support phase) when pre and post orthotic dispensing is measured.

    Dananberg, HJ, Guiliano, M, “Chronic Lower Back Pain And It Response to Custom Foot Orthoses”, Journal of the American Podiatric Medical Association, 89:3 March, 1999 pp109-117

    Dananberg, HJ, “Gait Style and Its Relevance in the Management of Chronic Lower Back Pain”, In Proceedings, 4th Interdisciplinary World Congress of Low Back & Pelvic Pain”, Ed, Vleeming, A, Mooney. V, Gracovetsky, S, Lee, D, etal, November 8-10, 2001, pp 225-230

    Simon did cite a number of papers including the one from Canada. The Canadian paper did not find any significant change in hip ROM, but used subjects with "moderate to severe Fhl". While it did not described the joint measurements, from the sounds of it, used subjects with hallux limitus...and not the functional variety (which either fails to dorsiflex during gait or doesn't...there isn't a grading system that I am aware of). If these subjects did have arthritic joints, there is no wonder that they did not see an immediate change relative to orthotic useage.

    While far too complex to describe here, the basic concept in LBP and gait involves the amount of hip extension present during single support phase. The failure to achieve a full 15 degrees leads to a situation where stress to the iliopsoas occurs and causes any number of problems. I have an online article available at http://www.vasylimedical.com/resources/articles.html. Scroll down to find the article on gait related lower back pain.

    Howard
     
  25. David Wedemeyer

    David Wedemeyer Well-Known Member

    Howard

    Thank you for the references. As a Chiropractor who's profession seems unerringly committed to providing orthoses based on spinal and pelvic complaints I am always searching for literature to support this. This is not because I prescribe accordingly, but because it is such a mainstream practice in my profession.

    I would like to see this type of claim validated because it is such such a widely held belief and marketed by one company in particular. Of course the main problem is that the product that they are marketing en masse has limited clinical application as a truly custom, functional FO in my opinion.

    Your comment regarding the sagittal plane does make a great deal of sense to me. I have read some of your papers on first ray function and adhere to many of you theories regarding the subject. I will read up on your studies regarding low back pain and foot function.

    Do you believe that excessive pronation moments can lead to structural changes such as forward rotation of the pelvis, increased lumbar lordosis and disc wedging over time that cause LBP?
     
  26. Howard,
    You've known me long enough to know what's coming, so I'll come right out with it: how do you know that: "failure to achieve a full 15 degrees leads to a situation where stress to the iliopsoas occurs and causes any number of problems" ?

    I did scan the link you suggested but the text was so small and my eyes are getting more tired with age that I may have missed the evidence you provided therein for this statement. Perhaps you could help me out here because I'm struggling to find a reference that demonstrates significant change in kinematics of the hip with foot orthoses of any kind :confused:. I take on board your point re: the Canadian study, perhaps if anyone knows the authors they could comment? Although it may be complicated, perhaps it might be helpful if could you explain how reduced hip extension results in increased stress to iliopsoas?

    Cheers,
    Simon
     
  27. Dananberg

    Dananberg Active Member

    Simon,

    The articles from the Vasyli website can be downloaded and printed....really saves your eyesight. ;)

    Hip extension allows for both longitudinal ground thrust as well as pre-load (read as: store potential energy) for swing phase. When single support ends with contralateral heel strike, the trailing limb IMMEDIATELY reverses from extension to flexion. This permits the limb to utilize its own weight to "collapse" into flexion, with the gastrox providing a burst from below, and the spinal engine driving this from above. Just at toeoff, the iliopsoas group fires and swing phase is begins. Its an elegant combination of energy storage/return with efficient muscle action.

    The less rearward extension of the hip during single support phase however, the less forward flexion available during the preswing phase and thus a greater repetitive demand on the iliopsoas. Since the psoas actually originates from the disks and vertebra of the LS spine, the potential to create a repetitive and perpetual stress load is very real. Kapanji showed that when the femur is fixed and the iliopsoas fires, it is the LS spine that is rotated. Intervertebral disks are very strong to very vertical load, but far weaker to rotational shear. When this is repetitive, it can either weaken a disk, or act as Simons and Travell called a "perpetuating factor" when the disk is previously injured through other factors.

    Those who treat lower back pain know it is characterized by many remissions and frequent exacerbations. Deyo showed a 71% recurrence rate in 12 months with subjects having a history of "back attacks" when localized methods of care are used to manage symptoms (ie, manipulation, PT, NSAID'S, etc.). When one considers gait style, and specifically, the maximum amount of hip extension during single support phase, the outcomes suggest a rather pronounced reduction in the recurrence rate. My 1999 JAPMA paper with Michelle Guiliano demonstrated only a 16% recurrence rate in a 12 to 24 month f/u period when CFO's made via sagittal plane principles are utilized. Since the entire focus is to improve extension mechanics, and this can be shown to dramatically decrease the recurrence rate, I do believe this shows a strong correlation to extension ability and CLBP.

    Hope this answers your question.

    Howard
     
  28. David Smith

    David Smith Well-Known Member

    Dear Dr Dananberg

    You wrote
    Whilst I generally agree with your saggital plane theory I find it difficult to follow your premise above, if it is correct to summarize as the following -

    If the extension of the support leg is short then the psoas is required to work harder during the swing phase to achieve full flexion. The psoas works harder therefore the lumbar lordosis is increased. This increased lordosis increases local stress in the lumbar spine and results in pathological changes.

    Then I query this in several ways

    1) Surely taking short step tends to reduce gait forces in general

    2) If there is a reduced hip extension then there is equivalent reduction in hip flexion and so there is no increase required in psoas action.

    3) To see an increase in psoas action, by your proposition, would require a greater flexion phase relative to extension phase. I don't think this is seen, is it?

    Can you clarify what you mean please

    Cheers Dave Smith
     
  29. Dananberg

    Dananberg Active Member

    Dave,

    If you were to throw a baseball, or kick a soccer ball, you would either first reach back with your arm, or first pull your leg backwards into full extension and then kick or throw forwards. Both of these would be examples of pre-load. (Let's forget lordosis for the time being....to complex before we get the basics movement concepts down.)

    During walking, the same is true. How do you develop sufficient speed for forward flexion (pre-swing acceleration), if insufficient pre-load of extension did not occur?

    If the trailing limb begins its normal pre-swing motion from the extended position, then there is sufficient momentum...and at the time the psoas fires, the limb is already moving forward. If there is limited pre-load (read as: limited extension), then there is insufficient momentum of the pre-swing limb, and the psoas must initiate rather than perpetuate forward motion. Considering that each limb weighs 15% of body weight....this can become quite the stressful event. If this occurs over enough cycles....symptoms can and do occur.

    It is really quite simple...and sounds like I did not explain myself clearly. Does this make sense now?

    Howard
     
  30. Thanks Howard, I was really interested in the 15 degree bit and where this figure comes from? You seem to be suggesting that someone with 16 degrees extension will be fine, while someone with 14 degrees will be pathologic. I wanted to know were this "magic" number came from?
     
  31. Dananberg

    Dananberg Active Member

    From my experience, 15 degrees of hip extension during single support phase seems about normal. Usually, patients who have 14 or 16 degrees are fine.....and never even consider this change an issue. It is those with < 10 degrees (ie, 1/3rd of normal or less) who I would consider pathologic.

    Howard
     
  32. Thanks- I guess from your reply that this is an experiential thing and not published with data to support anywhere?
     
  33. Dananberg

    Dananberg Active Member

    I believe have read this (15 degrees of hip extension) in Inman's original text on Human Walking....but I am not 100% sure of this.

    What's far more important than the number of degrees associated with hip extension, is whether the knee fully extends during single support phase, or it remains flexed during this same period. Should the knee flex during the mid step period, it is simply impossible for the hip to extend....and with it the ability to store potential energy to be used later to induce an efficient pre-swing motion.

    Howard
     
  34. David Smith

    David Smith Well-Known Member

    Dr Dananberg

    From first hand experience I have no doubt that footwear and FFO's can influence a change in the forces acting about the lumbar spine and significantly reduce pain.

    You wrote
    Yes I read your post and the Vasyli paper and I just needed to be clear this was what you where saying.


    Even so there is still pre load since the shank is trailing the knee and hip gravity will cause a flexion moments about the hip and an extending moment about the knee and the leg can still swing thru.

    Perhaps I'm just severely confused:empathy:

    Regards Dave
     
  35. Dananberg

    Dananberg Active Member

    Dave,

    Good conversation.

    I think you are not seeing the forest for the trees. You asked about speed of gait and lower back pain. Patients with lower back pain do walk VERY slow! The worse the pain, the slower they go. The slower they walk, the less momentum they have, and consequently requirer greater muscular action to accomplish the same task. It eventually overwhelms the system. While obviously not true in all cases...this is an interesting way to view it: "you don't limp because you hurt...you hurt because you limp".

    As far as your sport comments, you are correct. You won't get hurt throwing softly....but if you try to throw hard and use poor mechanics...you will certainly get hurt.

    You also wrote "However the acceleration of the swing leg due to gravity is a constant." Again...you are correct. However, position plays a roll. If I place a ball on the floor, gravity is certainly acting on it....there is just no acceleration. If I drop it to the floor from eye level....the effect of gravity is the same....but this time it accelerates it to the floor. It is actly the same in walking. Gravity is always there to assist, you just have to be able to place your limb in the right position to maximize its effect. Gravity can accelerate the limb about the hip joint provided the hip is extended. If there 0 degrees of extension...the it will accelerate it downward and not forward....and this will only serve to further stress any hip flexor activity.

    The neurology for swing phase is hard wired. (Herman, "Neural Control of Locomotion" 1976). Infants exhibit a swing phase reflex long before they are able to bear weight. The neurologic signal (probably linked to opposite heel strike) to the psoas causes firing regardless of whether the limb is efficiently positioned and in motion or not.

    The more potential energy available for preswing (re as: extension), the less stress on the psoas and secondarily the LS spine. Its not that you can't create swing phase....you just don't do it efficiently. After sufficient cycles (measured in the multimillions) and depending on a variety of other risk factors (smoking, posture and genetic issues of the disks, diet & exercise, etc.) stress reaches a tipping point and pain develops and all too often doesn't stop.

    We can talk about the effects of decreased lordosis next, but I want to make sure that this part is clear. Let me know.


    Howard
     
  36. David Smith

    David Smith Well-Known Member

    Howard

    Sorry to take so long to get back to this thread but I've been busy doing my year end tax accounts. They are done now so I'm feeling quite righteous now.

    So back to the thread --

    yes I see the trees but they bear strange fruit and I'm not quite believing my eyes :confused:

    Any analysis of internal forces of gait have always shown forces reduce as gait velocity reduces. What you are saying is that in the psoas forces increase as gait slows. Logically this would suggest that slowing down gait so that you appear to be standing still will result in huge forces in the psoas. I would suggest this is unlikely since a graph of this would have to show an exponential curve (fig2)approaching infinite force as the velocity aproaches zero. Or there would have to be some peak in the curve (fig 1) where as the gait slowed more the forces decreased again. Either one seems intuitively wrong.

    [​IMG]

    Has there been any EMG (difficult I know) to test this theory?


    I didn't know this. I cannot get the paper, it is cited by many but not available anywhere, would it be possible for you sent it to me? -foothouse@talktalkbusiness.net

    Cheers Dave
     
  37. musmed

    musmed Active Member

    Dave and Howard
    I is still alive!

    What about the first step. I have just looked into the mirror, I certainly did not go backwards with my body first, but do not ask about the brain.............

    Trust you are all well.
    Auckland is not pretty (weather wise)
    Regards
    www.musmed.com.au
     
  38. efuller

    efuller MVP

    I'd been meaning to get back to this quote. Certainly, the hard wiring can be worked around. Is a limp hard wired. I recal a study presented at the American Society of Biomechanics in the early 1990's (Howard, were you and Pat Laird there?) where there was a presentation of walking in decerbrate cats. On level surfaces the walking was "hard wired" as determined by EMG of the walking muscles. Then, when they had the poor kittys walk down hill the wiring changed. So, the reflex may be there, but it can be overcome (it has to overcome) if the need arises. Sometimes you would rather climb a tree as opposed to keep walking. So, it is hard wired up to a point where the demands of locomotion need to overide it.

    I agree with Dave's point about the psoas firng as you approach zero speed.

    The alternate explanation is that you get increased ankle push with more hip extension. Akle push allows the hip to extend farther while maintaing lower stress on the psoas. But, we have been around this stump before.

    Regards,

    Eric
     
  39. Dananberg

    Dananberg Active Member

    Dave,

    You wrote "Any analysis of internal forces of gait have always shown forces reduce as gait velocity reduces. What you are saying is that in the psoas forces increase as gait slows. Logically this would suggest that slowing down gait so that you appear to be standing still will result in huge forces in the psoas. I would suggest this is unlikely since a graph of this would have to show an exponential curve (fig2)approaching infinite force as the velocity aproaches zero. Or there would have to be some peak in the curve (fig 1) where as the gait slowed more the forces decreased again. Either one seems intuitively wrong."

    There is a definite efficiency point for walking. If too fast...you change to running. If you slow down, momentum is reduced....thus requiring greater muscular activity. It was this effect to which I was referring. While your curves are very nice, from a clinical standpoint, ALL walking speed is an average, since speeding up during single support and slowing during double support is normal. The slower you walk, the less momentum you have, and thus require greater muscular activity. I have actually seen this effect many times with treatment of subjects walking. Once treated appropriately, speed of gait increases, and breathing actually becomes far less labored. On my visit to Australia this past May, this was observed during a workshop session in Melbourne. Walking slowly has its costs, and efficiency is one of them.

    Howard
     
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