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ZOOS lower value

Discussion in 'Biomechanics, Sports and Foot orthoses' started by markjohconley, Apr 18, 2016.

  1. markjohconley

    markjohconley Well-Known Member


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    With the 'zone of optimal stress' (Spooner) why is there a low value of the range? Is ZOOS referring to 'acceptable' strain values or is it referring to 'performance'? If the former why is too low a stress within a tissue not optimal? Thanks, mark
     
  2. due the reduced " training " you will get atrophy if the stress is too low
     
  3. markjohconley

    markjohconley Well-Known Member

    Tendons, ligaments atrophy?, mark
     
  4. Griff

    Griff Moderator

  5. markjohconley

    markjohconley Well-Known Member

    "Strain values above this range will lead to increases in the cross-sectional area and stiffness of tendon and ligament, whereas strain values below this range predict decreases in these parameters" Thanks Mike and Griff (just listened to your podcast with James Dunne; that's what got me started)
     
  6. markjohconley

    markjohconley Well-Known Member

    Further query, sorry, so this lower limit of the range of the ZOOS lies somewhere along the 'elastic region' of the stress-strain (load-deformation) curve; and unlike the upper limit, it would be difficult, short-term, to assess whether the stress (resistance within the cells of the tissue) is within or below the ZOOS, yes/no, thanks, mark
     
  7. David Smith

    David Smith Well-Known Member

    Hi Mark

    Maybe this attached paper will go some way to explaining stress related growth and remodelling of body tissues.

    Cheers Dave
     

    Attached Files:

  8. Mark:

    The zone of optimal stress (ZOOS) is a concept which states that tissues subjected to very low loading forces will atrophy over time and also that tissues subjected to very high loading forces will undergo plastic deformation over time and become injured (i.e. partial or complete rupture, tear, stress reaction, stress fracture, fracture, etc). Therefore, the idea of ZOOS is that there is a range of magnitudes of compression, tension or torsion stresses that a tissue can be subjected to over a given period of time whereby the tissue neither atrophies (or weakens) nor becomes injured.

    The stress-strain curve of a tissue under load is a short term measurement that basically accounts for the current microscopic structure of the tissue in question (i.e.. bone, tendon, ligament, muscle, skin, fascia, cartilage). The stress-strain curve does not, however, take into account how a tissue may atrophy over time when subjected to lower loads or hypertrophy over time when subjected to increasing loads.

    In answer to your specific question, there is probably no way to know exactly whether when we see a tissue functioning in its elastic range that the tissue is going to atrophy, stay the same or hypertrophy with that load. However, we could reasonably assume that if the loads are high, just below the plastic range but still within the elastic range of the stress-strain curve, rather than being very low, then the higher loads will most likely cause tissue hypertrophy rather than tissue atrophy.
     
  9. markjohconley

    markjohconley Well-Known Member

    Thanks David Smith and Prof Kirby
    David, I'm still battling through the physics in the article; with me it's, 'wow that concept was easy', immediately followed by, ' did I just miss a paragraph?'; as for most of the formulae, leave that to the physicists like yourself. but still enjoying it.
    Prof., exactly, gone into my special word.doc file, just watched a webinair of yours, have taken the liberty to copy it to a word.doc, not for use other than myself, just because 'it sinks in' better from a hard copy, thanks
     
  10. markjohconley

    markjohconley Well-Known Member

    David, thanks for recommending the article; I tried, I removed Method (as I wasn't assessing the merits of the article) and Results; down to 3591 words, a few of which I actually recognised and knew what they meant; the word.doc file had definitions, which I needed to insert to assist my comprehension) throughout. I feel I have lost the will ..... it's taken several hours; my wife insists, for my health's sake to give up ......... truly you are a physicist, as this is not PHY101, I remember that well, even got a credit!

    All the best, and thanks again, mark
     
  11. David Smith

    David Smith Well-Known Member

    Yeah Sorry Mark - I didn't intend for you to understand the physics maths but rather to understand that there is a tangible way to measure and characterise the relationship between load and changes in tissue properties and the tendency to remodelling to accommodate those loads.
     
  12. Agreed and good discussion.

    One of the most important things to understand about the zone of optimal stress (ZOOS) is that it is "dynamic" and will change on a daily basis and even within the day too.

    Something for everyone to think about. Lets say we take an anterior talo-fibula ligament: in-vivo, we load that ligament with just enough force to load it outside of the upper limit of it's ZOOS in a single load-unload cycle; with just enough load to induce plastic set in the ligament. The resting length of the ligament is now longer, agreed? When we re-load this tissue what changes might we observe in it's stress/ strain curve and why (hint- something tell's me to wind my "neck" in here;-))?

    By inducing plastic set in the tissue we have altered the tissues ZOOS- agreed? We now modify the loading with a foot orthosis to ensure that the load applied to the tissue is always within it's new ZOOS: does the now elongated ligament remain elongated forever with the concommittant changes in it's stress/ strain behaviour or does it remodel over time back to it's original length and material characteristics? See Mueller 2002... then define "maintenance".

    I'm reminded here of Janda who cautioned against strengthening "long-weak muscles" in favour of addressing the length first... while the length/ tension relationship of active, contractile tissues has been discussed, I'm not sure the same can be said of passive tissues... anyone?
     
  13. Should read "talo-fibular" not talo-fibula BTW- fat fingers and a touch of the cockney.
     
  14. I first want to know when we are going to write the paper on ZOOS, Dr. Spooner? I mean it has been just a month shy of 10 years (June 1, 2006) since you first coined the term Zone of Optimal Stress or ZOOS.

    New Goals for Podiatric Biomechanics (post #130, June 1, 2006)

    Good discussion and glad to see Dr. Spooner coming out of hibernation....;)

    Since each of the body's structural tissues (i.e. bone, cartilage, muscle, tendon, ligament, and fascia) have different load-deformation characteristics to compression, tension and torsion stresses and each of these structural tissues heal, atrophy and hypertrophy by different molecular mechanisms and at different rates, the ZOOS for each of these structural tissues may need to be modified for each specific tissues. In other words, ligament, tendon, fascia, bone and cartilage don't have the potential for hypertrophy that muscle has and muscle will probably will hypertrophy and atrophy at much faster rates than these other structural tissues. This will likely affect the determination of temporal pattern of ZOOS for muscle compared to the other structural tissues.

    In addition, some tissues are very good at resisting compression forces (i.e bone) while other tissues are not so good at resisting compression forces (i.e. ligament, tendon, fascia) since they are better designed to resist tension forces. I believe that before we describe the ZOOS for each tissue, we must first describe whether we are discussing compression stress, tension stress or torsion stress since each tissue may respond quite differently to each type of stress.
     
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