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The importance of the venous foot pump

Discussion in 'Biomechanics, Sports and Foot orthoses' started by scotfoot, Feb 13, 2019.

  1. scotfoot

    scotfoot Well-Known Member


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    It has been long been understood that the venous foot pump and the calf muscle pump are present to counter the effects of gravity and assist with the return of venous blood to the heart .

    However , it now seems , however incredible it may sound , that although the motion of the legs during gait clearly generate considerable centrifugal forces which would hinder venous return , no study has ever been made of these forces .

    In light of this , it is entirely possible that the venous foot pump and the calf muscle pump are far more important than previously realised .

    Astonishing . Just jaw dropping if true .

    Gerry
     
  2. scotfoot

    scotfoot Well-Known Member

    Further to the above , there is some evidence that the functioning of the calf pump can be improved with exercise , but it does not look as if similar evidence has been sought for foot pump function .
     
  3. scotfoot

    scotfoot Well-Known Member

    Note ;In post 1 " centrifugal forces" should read " centrifugal effects "
     
  4. scotfoot

    scotfoot Well-Known Member

    If you start to consider the centrifugal effect on venous return , then perhaps it might be easier to better help with venous reflux during gait .

    For example , if centrifugal effects are greatest as the foot rapidly decelerates during heel strike ,then might it be possible to design a garment ,or accelerometer triggered device , that will exert external pressure on the calf at the exact point in the gait cycle when reflux past incompetent venous valves is likely to occur ? This applied external pressure may need to be of only very short duration .

    That is just an unexplored idea of course but you can see how realizing the importance of the the centrifugal effect on venous return changes ones focus .


    Here is a link to a thread on this subject on a site called Biomch-l

    Centripedal forces and the calf muscle pump - Biomch-L


    https://biomch-l.isbweb.org/.../31986-Centripedal-forces-and-the-calf-muscle-pump

    7 Feb 2019 - However what about the centripedal forces and centrifugal effect ... but none replicate the additional centripetal forces encountered during gait .
     
  5. Seamus McNally

    Seamus McNally Active Member

    Do you think compression hosiery might assist in a less precise way?
     
  6. Rob Kidd

    Rob Kidd Well-Known Member

    I think you would do well to broaden your outlook and recognise that accessory pumping mechanisms are the norm in all "complex" species (I know that it politically incorrect, but know no other way of saying it). When I was a biology undergrad we did a case study of accessory pumping by the "gill hearts" in octopodi - its routine. Bipedality has given HSap (and its precursors) a unique problem: bluntly put, how to shovel the proverbial up hill......... I do not know of any quantitative studies of the venous calf pump - it sounds interesting.
     
  7. scotfoot

    scotfoot Well-Known Member

    Hi Seamus ,
    In reply to your question " Do you think compression hosiery might assist in a less precise way? " my understanding is that such garments help with circulation in the lower limb but cannot stop reflux past incompetent veins

    . If reflux is specific to a particular point in gait, for example just prior to the heel touching the ground ,then" external venous valves" might be possible which would prevent reflux being caused by the centrifugal effects generated during gait .

    The system would involve bands of electrically responsive material ,which could contract and relax in a rapid fashion , being placed around the leg at appropriate points along its length . The system might be controlled by an accelerometer worn around the ankle and even powered by materials which can produce electrical current by fabric movement . All the bits an pieces for such a system already exist .
     
  8. scotfoot

    scotfoot Well-Known Member

    Hi Rob ,
    It's good to hear you think I should broaden my horizons as certain elements on Podiatry Arena seem to think I should narrow them and stay off the forum .
    For a "HSap ( and its precursors ) " I suspect centrifugal effects are/were more of an issue for venous return than gravity . Certainly at least as important .
     
  9. efuller

    efuller MVP

    Why do you think centrifugal effects are close to the effects of gravity. Have you read any papers that have done calculations. The angular velocity of the leg is not very high. It's not like you see mud, or even drops of water, go flying off of feet at the end of every swing phase.
     
  10. scotfoot

    scotfoot Well-Known Member

    From Eric's Post
    Question
    "Have you read any papers that have done calculations " Good question .

    To date I have not read a single paper that even mentions the centrifugal effects of gait on venous return let alone contains calculations on the subject . And I have looked .

    Question
    "The angular velocity of the leg is not very high "
    During walking that is true but the problem with regard to venous reflux may lie with short phases of acceleration and deceleration of the foot/leg pendulum system . If the superficial veins could be transiently occluded during these phases then perhaps reflux could be controlled .

    I have not looked into transient vessel closure in the deep venous system but since veins will collapse at far lower pressures than arteries a transient , "intelligent "," semi tourniquet" /"external valve" system might also work for these deep vessels .
     
  11. efuller

    efuller MVP

    So, you have no reason to suspect the above. It is an interesting research question. You should not pick a side without at least thinking about the numbers.
     
  12. scotfoot

    scotfoot Well-Known Member

  13. scotfoot

    scotfoot Well-Known Member

    Rob ,
    Going back to your point about looking at the rest of the animal kingdom , I have being trying to find anything (fish/fowl/human made ) that moves fluid by the sole means of the stretching of a fluid holding vessel or tube .

    Plenty of water dwelling creatures move by constricting vessels via appropriately placed musculature and thus expelling water but I cannot find any examples in either the animal or human worlds of a" stretch vessel " pump .

    In light of this , the emptying of the deep plantar veins by a completely baseless "bow string effect" , seems to me to be more extraordinary every time I read a paper on the subject .

    As a former professor of anatomy ,do you have any opinion on the matter ?

    Gerry
     
  14. scotfoot

    scotfoot Well-Known Member

    Some further quotes from the sister thread on biomch-l which also look at Honert and Zelik's recent soft tissue work paper.

    Quote -
    A very interesting paper was just published by the Karl Zelik lab on soft tissue work during early gait (see below ) . Such soft tissue work would include the deformation of the heel pad and compression / distortion of the other tissues of the foot .

    It seems to me that the compression of the tissues that lie between the bony arch of the foot and the plantar fascia would also play a large role in the soft tissue work done by the foot .
    If that is indeed the case then one might expect to see a lower contribution from this source when walking uphill but a higher , and later contribution when walking downhill (foot slapping action ) .

    I would be very interested to hear what Karl and Eric think of the above .

    Gerry

    Paper Foot and shoe responsible for majority of soft tissue work in early ...

    https://www.ncbi.nlm.nih.gov/pubmed/30769210


    And
    Re: Venous foot pump

    Anyone who might have read my last few posts will be aware that my experimental equipment consists of a half empty bottle of HP sauce and a water filled surgical glove . This is more of the same !

    The post above mentions a paper , very recently published by Hornet and Zelik , which looks at soft tissue work in the early stance of walking .

    The post also raises the question of whether the tissues between the bony arch of the foot and the plantar fascia are compressed during gait and so contribute to soft tissue work .

    So let's take the surgical glove, adapt it ,and use it to demonstrate tissue compression between the bony arch and the foot .

    Take the glove ,empty it of water and tie off the fingers . Now turn it inside out and fill it again with water . Now tie off the top of the glove so that you have a small water filled sphere .
    Next , place your cupped hand ,palm down , on a table . The lateral border of the hand lies flat on the table but the medial aspect will form an arch analogous to the medial arch of the foot .

    Now place the water filled sphere under the arch /cupped hand , then press down to represent the lowering of the bony arch of the foot during weight acceptance during gait . You will notice that the sphere is compressed between the hand and the table (analogous to the plantar fascia ) and so it bulges inwards . Now place your free hand so that it stops the water filled sphere from bulging inwards ( this hand represents the medial part of the plantar fascia ) .You can appreciate how the water trapped in the glove is now pressurized as the cupped hand is pressed down .

    Note ; in the case of the foot this system will not prevent the foot from pronating as the bony arch and the fascia will lower towards the ground as part of the same unit . Instead the intrinsics will act as
    (1) a pressurized core reducing shear forces between the components of the bony arch
    (2) an energy sump (soft tissue work )
    (3) a pump for moving blood out of the plantar venous plexus


    The intrinsic can of course do all of the above whilst at the same time acting to shorten the foot or reduce pronation , if they contract with sufficient force . The mechanism by which these muscles can contract whilst under transverse pressure is explained in this thread .(below )

    Any thoughts ?

    Hydraulically discrete fascicles in skeletal muscle [Archive ...



    https://biomch-l.isbweb.org/archive/...p/t-28655.html




    13 Feb 2016 - 2 posts - ‎1 author
    If the perimysium is sufficiently impermeable then might it be possible that each fascicle is able to funct​
     
  15. scotfoot

    scotfoot Well-Known Member

    THE WHOLE FOOT IS A PUMP ! ( almost )

    After a lot of reading on the subject it is starting to look to me like almost the entire foot is an "oseofasical pump " dependent for its power on the changing shape of the osseous components of the foot during weight acceptance .

    As weight is accepted onto the reference foot during gait , the medial and lateral longitudinal arches and the transverse arch are compressed , leading to increased tension in the interconnected deep and superficial fascial structures that envelop the foot . This increase in tension causes compression of the soft tissues of the foot including most of the venous system , dorsal and plantar .

    Fox and Gardner produce interesting before and after pictures of the coupled drainage of the dorsal and deep plantar venous components of the foot , below ( note the almost total expulsion of blood from the venous components of the foot between the weight bearing and none weight bearing conditions) . The fascially related , coupled drainage of the plantar and dorsal aspects of the foot mean that perforator veins need not have valves .

    The pressure generated by the foot , an osseofascial pump , increases with increased ground reaction forces allowing venous return from the foot to be maintained as centrifugal effects increase .

    The venous pump of the human foot--preliminary report. - NCBI

    https://www.ncbi.nlm.nih.gov/pubmed/6616290
    by AM Gardner - ‎1983 - ‎Cited by 169 - ‎Related articlesBristol Med Chir J. 1983 Jul;98(367):109-12. The venous pump of the human foot--preliminaryreport. Gardner AM, Fox RH. PMCID: PMC5077034.
     
    Last edited: Mar 3, 2019
  16. scotfoot

    scotfoot Well-Known Member

    Following some feedback ,the mechanism by which the whole foot becomes an oseofascial pump is not immediately apparent from the explanation I have given above , so this post is a bit of further explaination .

    Quote from above -

    "As weight is accepted onto the reference foot during gait , the medial and lateral longitudinal arches and the transverse arch are compressed , leading to increased tension in the interconnected deep and superficial fascial structures that envelop the foot . This increase in tension causes compression of the soft tissues of the foot including most of the venous system , dorsal and plantar ."

    A way of understanding this is as follows .

    Cup your hand as if you were trying to carry a little water in it or as if you were trying to cover a small egg on a table with your hand without crushing the egg . Maintain that hand shape as a friend puts a paper bag over the hand ,tightens the bag a litle to take up any slack and then tapes it in place with a few short pieces .

    So now you have something very roughly analagous to an arched foot enveloped in fascia . Now place your hand flat on a table top and push down on top of it with your other hand . As the hand (foot) flattens the paper bag becomes tensioned . The bag represents both the deep fascia and the superficial fascias of the foot

    In the foot the plantar fascia on the plantar aspect of the foot is continous with the fascia dorsals pedis . The superficial fascia is also continous going from plantar to dorsal .


     
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