Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
QUESTIONING THIXOTROPY AND MUSCLE / FASCIA PLASTICITY-ELASTICITY
#1
https://www.painscience.com/articles/doe...thixotropy

https://www.painscience.com/articles/pal...idolia.php

https://www.painscience.com/bibliography...plasticity

https://www.painscience.com/bibliography.php?stecco10

https://www.painscience.com/biblio/fasci...ation.html

https://www.fasciaresearch.de/faq
Reply
#2
ROBERT SCHLEIP - on fascial contractility

https://dl.anatomytrains.com/fascial_fitness.pdf

http://www.fascialfitness.net.au/article...l-fitness/

https://www.sciencedirect.com/science/ar...9202000670

https://www.fasciaresearch.de/publicatio...tility.pdf
Reply
#3
From Tom Meyers on Fascial contractility/elasticity

"...fascia is not actively contracting, it is simply elastically returning to normal length after being stretched. 
Like stretching a Theraband and then letting it go - it’s not actively contracting, it is simply making kinesthetic what you put in as potential when you stretched it.

Elastic storage in fascia and thus using its recoil for maximally efficient movement depends on two things:
1) Rhythmic movement of about 1 sec cycle - running, walking, skipping rope and the like - so no, no elasticity is engendered by yoga, Tai Chi, or strolling through a museum - hence museum feet.
2) Repetitive movement of this kind essentially squeezes the water out of the tendons or ligaments.  While that might seem counterproductive, ’soggy’ tendons are like a Tempur-Pedic mattress and thus incapable of good recoil.

It is not contractility that is shifted to the fascia, fascia cannot actively contract except via myofibroblasts, and that’s rare
The length change is shifted to the fascia - the muscle stays isometric, the tendon lengthens, recoils back to send you forward - voila! free energy.

If you look at fig 2 in Robert’s article:  

Old model - tendons stay the same, muscles concentrically contract to push us along
New model: tendons lengthen and shorten, muscle stay in isometric contraction (the truth within the muscle is more complex)

But the ’shortening’ of the tendon is not active - the energy of the stretch has to be put in there first by a stretch as the foot lands in gravity, and then it recoils naturally like a stretched Theraband, not with any active contraction, and it has to be within a second or the fluid medium will dissipate the stored energy. 

(Interestingly, sometimes you land and you don’t want an elastic response, like coming down from the hoop, but you don’t want to bounce up again but rather turn and head out for the other end of the court.  In that case, to avoid the elastic recoil, the muscles relax temporarily as you land, to reabsorb the elastic recoil into the muscle and you stay put.)

If fascia is held close over time, it will knit close, and this is (misnomer) called a contracture, but it’s the muscles that originally spazzed, and the fascia just went, “OK, if that’s the way you want it, we’ll support that”  

The one place where the fascia itself can be said to contract is the myofibroblastic - and even there it’s a cellular contraction within the webbing, not the ECM contracting itself.  Robert lays out the severe limitations on these myofibroblasts - how long they take to contract, and to relax, and the very few chemcial stimulants they respond to.  There’s no doubt how important they are in drawing the tissue together in wound healing but in sports?

I’ve stopped talking about them, not because they are aren’t important - apparently a lot of them together csn generate enough force to ’stiffen’ the TLF - but because people than take off saying ‘fascia contracts’ without the many qualifications.
Reply
#4
Thank you Tom, another question:
In his article, Paul says fascia, being tougher than kevlar, does not stretch. Am I misunderstanding him to mean that fascia is not elastic?
This makes me wonder... if this is the case, what is happening when muscles are under tension... are they elongating or is the net simply being deformed?

Frey
Reply
#5
From Tom, in response:


What do you mean by stretch? Collagen molecules, fibrils, and fibers, and then the fascial fabric as a whole - they are all very limited in elastic stretching. Elastin fibers stretch farther and more easily. But even tough fascia can stretch by 7-10% of length, storing elasticity with a high coefficient of restitution (super ball, not a nerf ball) This must be ‘collected’ or it will be dispersed a la our previous discussion. That’s elasticity.

Plastic deformation of the fascia - another, more permanent length change - is absolutely available to yoga stretching and rolfing. How much you can stretch the plantar fascia with down dog is a question, but myofascia is much thinner and more deformable.

The net inside a muscle is organized as a double lattice - like an onion bag - so the endomysium can allow the elongation of the muscle in eccentric load or relaxation without any deformation of the fascia - your just moving the onions inside the bag, or compressing and stretching the bag. Actually lengthening the bag is plastic deformation, and we can argue whether that is possible, I am quite sure it is, but I’ve been wrong before. If not, what you are getting is the sliding of fascicles within the muscles on each other by means of the perimysium. Observed already and very possible, and will result in a functional length change in the muscle even if none of the component parts has actually lengthened.

Jury is still out on the how, but not the what.
Reply
#6
Ok, so Paul is probably right as far as myofascia is concerned, the onion-bag net is deforming rather than the individual fibers changing their length. Plasticly deforming muscles or ligaments is something I actively discourage, as there seem to be too many adverse long term effects. In the documentary, "strolling under the skin", the researchers showed fascia that is nearly in a liquid state, where the individual fibers did appear to lengthen and regroup. 
I find it difficult to accept that living tissue would not give a bit when stretched... even the femur bends when a runner touches down in reception, according to my sources.
What do you think of this vid I did on walking?
Frey
https://www.youtube.com/watch?v=jy6tJZOQ0Ws
Reply


Forum Jump:


Users browsing this thread: 2 Guest(s)