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Does the windlass mechanism really work like we think it does?

Discussion in 'Biomechanics, Sports and Foot orthoses' started by NewsBot, Aug 16, 2018.

  1. NewsBot

    NewsBot The Admin that posts the news.

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    Influence of the windlass mechanism on arch-spring mechanics during dynamic foot arch deformation
    Lauren Welte, Luke A. Kelly, Glen A. Lichtwark, Michael J. Rainbow
    Journal of the Royal Interface 15 August 2018.
     
  2. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
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  3. scotfoot

    scotfoot Well-Known Member

    Interesting paper .
    So I have previously described an initial windlass phase , important during initial foot contact , and a secondary windlass phase which occurs through toe off .

    The authors of this paper seem to be saying the same thing but have described a different energetic model . In my model ,the energy absorbing , foot structure protecting model , involves the progressive paying out of wound fascia during weight acceptance whilst Welte and her colleagues have demonstrated that the full mechanism probably involves toe dorsiflexion leading to less initial rigidity , more controlled energy management within the foot ,with the mechanism I have described as the final part of the ending of the initial windlass phase .

    Here is a quote from their paper -

    " For instance, if the dorsiflexion of the MTPJ is limited before initial contact during gait, it may limit the elongation of the arch, and thus its energy absorption during impact, and subsequently affect the foot's ability to absorb shock. It may also cause the foot to deform differently, by straining different arch tissues, which would also modify arch energetics. Therefore, the windlass mechanism may be important during initial contact, as well as during push-off. "

    So what of foot stiffness during push off ? As demonstrated by Welte ,the plantar ligaments such as the long plantar ligament are less in play as the plantar fascia winds around the MTFJ during toe dorsiflexion through late stance /push off . Foot stiffness at push off may therefore be more dependent on the plantar intrinsic muscles than previously thought, and as well as support from the extrinsic muscles ,the role of the metatarsal parabola in producing relative movement of the met heads in a horizontal plane , is likely hugely important in foot stiffness .

    Looking at the first sentence from the quote I have used -

    "For instance, if the dorsiflexion of the MTPJ is limited before initial contact during gait, it may limit the elongation of the arch, and thus its energy absorption during impact, and subsequently affect the foot's ability to absorb shock. "

    - it can be inferred ,as I have previously said ,that footwear that prevents dorsiflexion of the toes , prior to foot strike , may lead to increased peak forces within the foot during weight acceptance .
     
  4. scotfoot

    scotfoot Well-Known Member

    Closely related to the above are these recent posts taken from threads here on the Arena which concern the initial windlass phase of gait and its relationship with " shin splints "and plantar fasciitis .

    from - Initial windlass phase and shin splints | Podiatry Arena

    Hi Steven
    Shoes in general should , in my opinion , allow the free dorsiflexion of the toes prior to foot strike to allow the initial windlass phase of gait phase to reduce strain ,if required , on the plantar foot structures and on the plantar fascia in particular.

    Even quite minimal shoes could restrict dorsiflexion if the toes are closely held in position to the sole of the shoe . For example , in middle to long distance tract athletes ,spikes with a closely fitting upper mean that the initial windlass phase of gait cannot function properly since pre strike dorsiflexion will involve the toe extensor muscles working against and bending the forefoot plate .

    Interestingly , at the Atlanta Olympics the tract was made of a less yielding material than normal to give faster sprint times . If memory serves the long distance runners complained of "shin splints " (a generic term well recognized by most runners) which they attributed to the track . I believe it more likely to have been a combination of the track and restrictive , if minimal , shoes .

    Here is a reference (1) that explains my idea of the two windlass phases . I am pretty sure of my ground here and others agree .
    (1)
    Windlass mechanisms - plural - and diabetes - Biomch-L

    https://biomch-l.isbweb.org/threads/31054-Windlass-mechanisms-plural-and-diabetes
    2 Mar 2018 - 7 posts - ‎1 author
    Post 1 So during the gait cycle the windlass mechanism is engaged and reversed twice . Going from heel strike to heel strike we have windlass ...
    Last edited: Jun 10, 2018
    Gerrard Farrell
    Glasgow



    And ,in relation to plantar fasciitis -

    Post 1
    It seems clear to me that there are two windlass phases during gait . The initial phases occurs during preparation for ground contact through weight acceptance and the second at heel off and through toe off . (see link to video 1)

    In my opinion it is very likely that a properly functioning and unimpeded initial windlass phase will substantially reduce the stresses to which all of the plantar tissues are subjected during gait and most especially during running with a midfoot or forefoot ground strike .

    In cases where footwear induced suppression of the initial windlass phase is the cause of plantar fasciitis then it stands to reason that resolution of the condition can never be achieved so long as the same footwear continues to be worn .

    Gerrard Farrell

    Post 2
    Further to the above , and in my opinion , it seems quite possible that certain types of footwear may cause musculo skeletal problems if worn for long periods .

    My understanding is that clogs are a common choice of footwear amongst nurses . I believe that shoes which require that the toes be pressed down against the sole of the shoe to hold the heel in place during the swing phase of gait , may habituate suppression of the initial windlass phase of gait ,causing unnecessary stresses on the plantar foot structures during gait , leading perhaps to plantar fasciitis .

    The actual act of keeping the heel in place over the course of a long working day may also lead to muscle fatigue in the plantar intrinsics and in the shank of the lower leg .

    The solution , subject to diagnosis and supervision by a qualified podiatric physician ( which I am not ) might include , amongst other measures -

    1 switching from clogs to a training shoe type of footwear with a wide and deep toe box
    2 re-establishment of the initial phase of gait via prescribed exercises

    Gerrard Farrell
     
  5. Seamus McNally

    Seamus McNally Active Member

    And interesting in the context of the great discussion thread you guys had on recently ( last week?) on intrinsic muscles and shock absorption. To paraphrase the great baseball quote ‘ I’m beginning to think all of this game is half mental.’
     
  6. scotfoot

    scotfoot Well-Known Member

    So as far as I can see , the paper" Influence of the windlass mechanism on arch-spring mechanics during dynamic foot arch deformation " is , in part , about what I have hitherto been calling the " initial windlass phase of gait" and about how this reduces load transients within the foot . The paper also discusses how , if footwear inhibits this phase , pathologies can arise .

    Again , as far as I can tell , referring to two windlass phases (with subsequent stress reduction ) and the importance of footwear not interfering with the initial phase ,was first proposed in the Arena thread linked to below .

    Link
    Windlass mechanism | Podiatry Arena
    https://podiatryarena.com › Forums › General › Biomechanics, Sports and Foot orthoses


    28 Feb 2018 - So during the gait cycle the windlass mechanism is engaged and reversed twice . Going from heel strike to ... Gerrard Farrell Glasgow. scotfoot .

     
  7. scotfoot

    scotfoot Well-Known Member

    Question ; What happens to the volume of filled space between the bony arch of the foot and plantar fascia as the foot flattens during gait ?

    If you are inclined and have a bit of spare time you can test this with a surgical glove .

    Tie off the fingers , turn the glove inside out , fill with water , and seal . Place this on a table (proofed against water damage) then cup your hand over the top so that the heel of your hand and the finger tips are touching the table . The outside of your hand should also in contact with the table leaving the water filled balloon to bulge out from under the medial aspect of the hand . Push down ( but obviously not hard enough to burst the glove ! )
     
  8. scotfoot

    scotfoot Well-Known Member

    So if you try this simple experiment you will immediately notice that as you press down the glove will bulge medially . This is because the area under your hand decrease as the hand flattens , and so it is with the area between the bony arch and the plantar fascia .

    So as the foot flattens , the tissues between the arch and the fascia will be compressed ? Yes .
    The high pressure generated in the plantar venous plexus which , during walking , empties in a fairy " explosive " fashion , indicates high pressures within the core tissues of the foot .

    So can muscle tissue act as a supportive skeletal component during foot function , helping to reduce shear stresses between the bones of the foot . Yes , it can, and probably does . In muscular hydrostats such as the tongue or an elephants trunk , muscle acts both as contractile tissue and "locked tissue " around which constantly changing muscle moments are created .
    .
     
  9. scotfoot

    scotfoot Well-Known Member

    So the connection with the MJ Rainbow paper above ?

    With the toes dorsiflxed , the area between the arch and fascia is at it greatest making compression (lengthening ) easier . As the arch lengthens the tissues at the core of the foot are pushed in to the nooks and crannies within their immediate local ( reducing sheer stress and stiffening the foot ) , compression becomes more difficult .

    With the viscoelastic properties of muscle being dependent on how actively it is contracting and with muscle able to resist work partitioning if muscle fibers or fascicles are evenly compressed through their lengths ( see thread on pod arena on " hydraulically discrete fascicles " ) ,you can see how easily even small amounts of intrinsic muscle activity can help regulate strain within the foot .

    I look forward to Professor Rainbows next offering .
     
  10. scotfoot

    scotfoot Well-Known Member

    So I re-read the Welte /Rainbow paper last night and was struck by fact that the windlass mechanism seems to be discussed more in connection with the initial phase of gait (during weight acceptance ) than the second windlass phase , during toe off . I find that a bit surprising .

    Worth noting too , that Hicks never described the windlass effect as being present as two phases and that that idea first emerged and was discussed , on this site , back in February ) .

    Sadly it's not so easy to read the paper now since , although it was initially open access , it is now behind a pay wall .

    Anyway , after kicking the metaphorical dog around the house a bit ( note that the dog is metaphorical ,I don't have a real dog ) I did come across an interesting sentence .
    Quote
    "More energy was absorbed and returned by the arch of the foot when the arch was compressed in the fast condition compared to the slow condition."

    This is exactly what you would expect if a viscoelasic material was subject to compression and strengthens the concept of the intrinsic muscles of the foot acting as a compressible core at the center of the foot .
     
  11. scotfoot

    scotfoot Well-Known Member

    I'm still baffled by this paper .
    Looking at method section , the project starts off in a time honored fashion by adopting an expiremental set up to look at the windlass mechanism during toe off .

    The paper states -
    "The force was applied to the knee, directly vertical to the navicular, with the shank at an approximate angle of 15 degrees to the vertical (similar to late mid-stance in walking , before heel rise [20]) (figure 2)."

    In other words this experimental set up and the results it produced , appear not to relate to the loading phase of gait , or early stance at all .

    So how did the authors get from an experiment ( and associated results ) about the energetics of the foot during late stance ,to the importance of a prestrike , toe up position and the energy absorption possibilities of an initial windlass phase during weight acceptance ?

    It has to be noted that , as far as I am aware , before this discussion,
    Windlass mechanism

    , on podiatry arena ,the importance of a prestrike , toe up position and the energy absorption possibilities of an initial windlass phase , had never before been discussed in the word of science .

    So how did the authors get from an experiment and results about late stance to this -
    Quote

    "For instance , if the dorsilflexion of the MTFJ is limited before initial contact during gait, if may limit the elongation of the arch , and thus its energy absorption during impact ,and subsequently affect the foot's ability to absorb shock .It may also cause the foot to deform differently , by straining different arch tissues , which would also modify arch energetics . Therefore , the windlass mechanism may be important during initial contact ,as well as push off . "

    What led this group to this piece of thinking around what I have been calling the " initial windlass phase of gait " and which only came onto the scientific horizon in February ?
     
  12. scotfoot

    scotfoot Well-Known Member

    So leaving aside the apparently referenceless introduction of the initial windlass phase , this is still a very valuable paper .

    What is doing what at toe off ?

    As the authors have described , the windlass mechanism is engaged at toe off meaning that the plantar fascia acts both to provide rigidity and plantar flex the toes to provide traction . The ligaments on the plantar surface of the bony arch are necessarily under less stress than might be expected because a more exaggerated arch means that distance between attachments is decreased .

    With regard to the intrinsic foot muscles , the engagement of the windlass mechanism will create a greater volume of space between the bony arch and the plantar fascia ( which is continuous from the medial to lateral aspects of the foot but with thickened areas ) allowing the intrinsic muscles to contact without having to overcome work partitioning (Siebert ) .This would improve their ability to produce force between origin and insertion .

    So lots going on .

    Surely the idea that the foot is a merely a biomechanical block attached to the body via the ankle joint should now be abandoned as hopelessly incorrect .
     
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