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Intrinsic foot muscles .A substantial collective mass .

Discussion in 'Biomechanics, Sports and Foot orthoses' started by scotfoot, Oct 3, 2020.

  1. scotfoot

    scotfoot Well-Known Member

  2. scotfoot

    scotfoot Well-Known Member

    One stand out for me from the imagers are the interosseus muscles . You get a real sense of how their mass might prevent the metatarsals from rubbing on the other structures which lie between said bones , causing irritation and inflammation .

    It raises the question of whether some neuromas , such as Morton's Neuroma ,might be effectively treated using strengthening and muscle mass building exercises . Indeed , Melinda has been successful in treating neuromas using exactly this approach .
     
  3. scotfoot

    scotfoot Well-Known Member

    Having looked around on the internet a bit , I can see that some authorities are recommending foot strengthening ( mass increase ) as a way of treating neuromas such as Morton's neuroma . In my opinion such exercises should focus on the toes remaining straight but flexing around the toe "knuckles " ( MTPJs ) , since this is the easiest way of strengthening the intrinsic muscles which have some toe flexor component .

    With regard to the intrinsics forming a collective muscle mass , the images produced by Smith and her colleagues help to illustrate how compression of the tissues that lie between the bony arch of the foot and the plantar fascia ,during weight acceptance , helps to dissipate harmful shear forces which might be generated during this phase of gait .

    Thus we have two examples here of how the intrinsic musculature influences foot function just by its presence alone . Or put another way , the intrinsics can fulfil a role in the foot without much contractile activity at all .

    With regard to the contents of the second paragraph ,the existence of the plantar venous pump ,which does not function by necking down or primarily through muscle contraction , more or less proves the point .

    Note ; the PVP is active in the foot during weight acceptance and as the muscles are lengthening . A group of lengthening muscles will not expel blood from vessels which lie between them since the pressure on such vessels is decreasing . Lengthening muscles can expel blood and act as pumps if they have sinuses within .
     
  4. scotfoot

    scotfoot Well-Known Member

    It has been suggested in the literature that modern cushioned shoes cause people to run with a heel strike rather than a forefoot strike and that this happens because the cushioning makes heel striking more comfortable than it would otherwise be . But could there be another reason ?

    Consider that most modern running shoes have toe springs . Add in an upper that further splints the toes in place prior to and during weight acceptance and you have a situation where the initial windlass phase of gait is suppressed . If you then try and run with a forefoot strike , the plantar fascia will be loaded more rapidly than it would be if the initial windlass were functioning optimally ,and perhaps that leads to proprioceptive outputs causing a subconscious switch to a less demanding ( in terms of the plantar fascia ) heel strike .

    If you think I am wrong about this" initial phase of gait" please watch the short video liked to below . It's only the last 20 secs that are relevant , so from 52 secs forward . In the video of a runner moving barefoot on a hard surface you can see the enormous energy absorbing effect that the toes provide when they move from dorsiflexed to a more plantarflexed position during weight acceptance . A toe spring with a stiff , shallow ,upper will likely greatly impact this mechanism by splinting the toes in a relatively fixed position .

     
  5. scotfoot

    scotfoot Well-Known Member

    Here is a radiograph of a foot that has been in the wars but which clearly shows the metatarsal parabola .What that refers to of course is the parabola that would be formed if you were to draw an arched line connecting the five metatarsal heads together . [​IMG]


    So far so good .

    Now what does this mean for foot function during gait ?
    Well , the fact that the metatarsals extend to different extents anteroposteriorly ,and the heads are not all in a neat row as Vankandesen et al seem to think , means that after heel off and during push off ,the met heads MUST move relative to each other if they are to" stay in contact" with the ground .

    You can see how this works in the 10 second YouTube video clip linked to below where the fingers represent the metatarsals ( not the toes ) and the finger tips the metatarsal heads .



    When you add in a transverse ligament linking the met heads ,the anteroposterior movement of the met heads causes a drawing together of the said met heads mediolaterally . Thus , as the heel lifts ,the foot becomes stiffer as the foot narrows . Nothing to do with fish fins !

    I believe the above is key to understanding the increased plantar pressures sometimes developed under the met heads during gait in the diabetic foot and the irritation of neural structures that can lead to neuromas between the metatarsals .

     
  6. scotfoot

    scotfoot Well-Known Member

    Physiotherapy exercises for foot health

    For the past 20 years , Susan Mayes has been very successfully looking after the members of the Australian Ballet .

    One of the exercises she has the dancers practice are calf raises with the foot /ankle in a neutral position . By neutral I take her to mean with the weight of the body evenly spread across the ball of the foot .Also ,my understanding is that she has the dancers lift up on the ball of the foot as high as they can.

    In my opinion , in getting the dancers to exercise in this way ,in minimal shoes or barefoot and on a hard surface , Mayes has been maintaining the health of the mechanism mentioned in the post above , long before the mechanism was ever described .
    Instinctive brilliance or conscious reasoning 20 years ahead of everyone else ?

    Calf raises in cushioned shoes will likely not be nearly as effective as supervised barefoot raises since ,with raises in cushioned shoes , the met heads will not be forced to move ,relative to each other ,to the same degree .

    If done under careful supervision , could Mayes's calf raise parameters be applied to progressively mobilize the feet of diabetics with increased plantar pressure under specific areas of the forefoot ?
     
    Last edited: Oct 14, 2020
  7. scotfoot

    scotfoot Well-Known Member

    In 2014 Luke Kelly produced his excellent Phd thesis . One of the chapters was titled

    " CHAPTER FOUR – INTRINSIC FOOT MUSCLES HAVE THE CAPACITY TO CONTROL DEFORMATION OF THE LONGITUDIUNAL ARCH"

    But do toe springs affect the mechanics of this "capacity to control" ;I would certainly think so .

    If you look at Kelly's rig for applying increased force to the foot you can see the foot is flat on the force plate . When the studied intrinsics contract the toes are pushed onto the plate ,but what if the plate only extended up to the MTPJ ? That is to say the plate is under the heel, MTPJ and rest of the foot but not the toes which are free to plantarflex unimpeded . In this set up the toes would have nothing to push against and so the muscles would effectively have no insertion point and so could not generate force to control arch deformation .

    If an individual puts on a pair of training shoes with a toe spring , stands on one leg and consciously pushes the toes of the standing leg down , the front of the shoe is pressed towards the ground . Thus the point of insertion of the intrinsics on the toes moves giving a reduced capacity for the intrinsics to control deformation of the arch .

    If intrinsic muscle activity helps reduce strain in the plantar fascia during constant weight shifting in standing workers ,then in the way described above , might this protective role be impeded by toe springs ?

    Any thoughts ?
     
  8. scotfoot

    scotfoot Well-Known Member

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