A clarification on "reflexive stability"

Brett Jones

StrongFirst Director of Education
Master Certified Instructor
Beast Tamer
Just to repost:
"  _____________ is the mechanism the body uses to maintain or restore joint stability after an imposed joint perturbation……In the case of joint perturbation, the processes include mechanoreceptor stimulation, neural transmission, integration of the signals by the central nervous system (CNS), transmission of an efferent signal, muscle activation, and force production.”
“Specifically, from a joint stability perspective, we define neuromuscular control as the unconscious activation of dynamic restraints occurring in preparation for and in response to joint motion and loading for the purpose of maintaining and restoring functional joint stability."

So if we "fill in the blank" with the term stability/motor control does that satisfy....
 

B.Hetzler

Level 3 Valued Member
It sounds like the big hang up is on the "anticipatory" aspect of reflexive stability.  I think it will clear things up if we use a better  term, feed-forward stability (lots of people throw around reflexive stability and don't get a full grasp of it).  " Perception contributes to anticipate movement by giving the individual information based on past experiences, on which he or she can anticipate movement."  Reflexive stability is better termed feed forward stability, it is anticipatory in nature, and predictive.  The CNS is pretty amazing, and things happen pretty quick.  This is why the world of motor learning you can see such rapid changes - its not a WTH moment, its called motor learning.

Individual joint stability is a great discussion to have, but outside of a lab it is a fallacy.

Proprioceptive stabilit is a great term.  However, it only relies on the proprioceptive system.  Just looking at single leg balance.   The proprioceptive system is just 1 of 3 contributors to balance in general- the other 2 being the visual system and the vestibular system.  So, if we use that term we are neglecting 66% of the input that the brain uses to just stand on one foot.  Let alone all the stored feed-back from prior single leg balance episodes...........

I coud see this disagreement going on for days.  Bottom line - the human body is amazing and very interconnected.  The CNS is that on a whole other level.  Every system of the body is involved in stability (whether it is reflexive or not).  Trying to sum it up with a single " reflexive stability is......." will be tough.  How about "reflexive stability is awesome and can't be trained (unless you understand the mechanism by which it works)"

The example of throwing a ball is great example, but doesn't really express true feed-forward stability. Catching a ball on the other hand.......completely dependent upon feed forward stability - having to track the ball, anticipate the trajectory, and then move the body and the arm into position to intercept the ball is THE example of feed-forward stability.

 

 

 
 

The Scientist

Level 3 Valued Member
Brett,

I would say that those terms would be acceptable there, but they are a bit vague. Certainly fine for speaking to patients/clients.

For everyone else, I think I cam up with a better way to describe all of this. here it goes:

Your body has three primary categories of control over most muscles (I'm simplifying, but that is fine I think):

1. Reflexes. These are simple, local, and fast. Imagine a person trying to do a spiderman crawl for the first time. They are wobbly and begin to lose balance. If they begin to fall to the right, the muscles on the left side of the abdominal wall will lengthen (unintentionally). This will activate the muscle spindle, which carries out the stretch reflex through the spinal cord (no brain) and those muscles contract. If it happens fast enough, they avoid falling.  This works, but it looks sloppy because there is little coordination.

2. Novel motor patterns. Doing something new requires your brain to use visual and proprioceptive feedback about the new task to make an attempt at generating a motor pattern that accomplishes the task at hand. So for the person trying their first spiderman crawl, they are taking in the landscape with their eyes and getting proprioceptive feedback from the relevant muscles, as well as the vestibular system. They will likely be bad at it the first few times, because the brain is making some guesses as to what will work. This means that reflexes are going to be busy working to correct mistakes. The wonderful thing about this is that the patterns of activation that work better get strengthen and stored in the cerebellum (unconscious), and the ones that fail get ignored. This leads to....

3. Learned motor patterns. The more you do it, the more the correct motor pattern gets strengthened. This is no different than writing or playing an instrument. The more you do it, the more "automatic" it becomes. It is not a reflex, but a set program of activation that has been reinforced because it worked well in the past and is stored in the brain for future use. The better these learned patterns get, the less you have to use reflexes. If the learned program is working, few mistakes will be made, meaning reflex arcs will have little work to do.

So I guess you could say that the poor, wobbly stability of someone new to a task is largely reflexive, and the smooth, coordinated stability of someone experienced in a movement is the subconscious control of the brain executing a thoroughly tested motor program.
 

jgruginski

Level 3 Valued Member
So where does the righting reflex fall into all of this? Since it isn't limited to spinal cord signals and is also not caused by rapid shortening of muscle, it seems like it shouldn't be called a reflex, but yet it is. So are we back to making a distinction between a reflex and reflex arc? And if there is that difference, then isn't calling it reflexive stability still okay?
 

B.Hetzler

Level 3 Valued Member
The righting reflex is a primative reflex that every baby is born with.  It is replaced as motor learning occurs and higher levels of the brain develop and motor engrams are formed.  If it doesn't, it will lead to problems later in life. It is just like the palmar grip reflex, and the rooting reflex.  All are survival based and occur at a brainstem level.

The "Reflexive" part of reflexive stability was a poorly selected descriptor - it is not truly a reflex.  A stimulis occurs, the brain and body react to that stimulis and responds both consciously and unconsciosly in a manner to produce the desired outcome.  All of this faster than conscious thought.  But not a reflex.
 

jgruginski

Level 3 Valued Member
Appreciate that Brandon. The righting reflex is controlled at the cerebellum and has multiple inputs including vestibular and visual. Also, you don't grow out of it liek the ones you referenced.  That's why I chose it as the example.  I was merely poking at the semantics of 'reflex' and how it seemed to be used synonymously with 'reflex arc'. Totally agree that reflexive stability isn't a reflex, but I don't agree that it can be lumped in with other automatic motor patterns as it never seems to exist at the conscious level. It always appears to be unconscious although I've love to look at research that shows where in the brain these signals come from. Perhaps 'unconscious stability' might be more correct, but sounds worse. Maybe "inherent' or 'innate' stability? Now I'm just having fun with words.
 

The Scientist

Level 3 Valued Member
Joe,
The term reflex refers to the entire system and the process that it carries out, and reflex arc refers to the physical neural circuit that carrie out the process. So every reflex (including the righting reflex) must have an arc. The can't be operated from each other.

"although I’ve love to look at research that shows where in the brain these signals come from."

What signals are you referring to?
 

Sean Schniederjan

Level 3 Valued Member
Scientist,

I'm not sure how to define "automatic" physiologically either, but maybe metaphysically.  A reflex is an effect (muscle contraction that is brought about by something else – stimulus, etc.) that cannot be other than it is.  “Necessary effect”

Here’s an example of how I think about the difference between a reflex and RS.  What you’ve been saying has made this clearer to me (whether or not it is accurate is another question).

-----------------------------------------------

Consider: stomp your foot into the ground as hard as you can.  Feel GM contract to stabilize the leg.

Is this stability contraction a reflex or no?

Take a person who has been sitting with one of their legs in habitual external rotation for a prolonged period of time (whoever has ears let them hear).

Have them stomp their imbalanced leg into the ground.

Is GM going to contract to stabilize that imbalanced leg?  Will that person have good hip stability?  [Anyone who is shaky on one leg should look at GM imo.]

What might be a “reflex” for a healthy leg is not so for an unhealthy one.

Contrast that situation example with this one.

Laterally flex your neck.  Feel oblique/QL contract synergistically.  Have a person with neck problems do the same.  This contraction HAS to happen in both cases.

These two situations lead me to this distinction between a reflex and reflexive stability –

A reflex is a muscle reaction that has to happen no matter what given the proper stimulus.  Reflexive stability is muscle action that should happen but might not based on one’s individual habits/movement patterns/etc.

Reflexive stability can be regained if lost.  Reflex can be made conscious.

--------------------------------------------

Brandon,

Re: rotator cuff.  Let’s combine what has been said on both sides.  The rotator muscles are develop by catching AND throwing.  We like to separate movement and stability, but the two are linked.  The muscles that throw a punch also operate in blocking punches.
 

Sean Schniederjan

Level 3 Valued Member
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC164311/

Aim high:

"Our premise is to present the athletic training community with an introduction concerning how the dynamic restraints are activated and controlled by the motor control system of the body. Our goal is that these papers may initiate common understanding regarding the terminology and underlying physiology associated with proprioception and neuromuscular control."
 

B.Hetzler

Level 3 Valued Member
So, this reflexive horse has been ridden into the ground.  I don't see any agreement on that topic.  How about coming at it from a different aspect.  What is Stablity?
 

The Scientist

Level 3 Valued Member
Sean,

In the first example the gluteus maximus is being activated to perform the movement (hip extension) and only stays contracted if you continue to push your foot into the ground. If I stomp hard and then quickly pull my foot up, the GM immediately relaxes to allow hip flexion to occur. This is not a reflex at all. It is a learned motor program.

In the second example, I don't follow. I can move my neck in any plane I want while avoiding any trunk muscle activity. If you let it happen, it will (learned motor), but you can modify if you want.

I would say that motor programs can be relearned if lost, but reflexes absolutely can't be made conscious.

I will look at the paper later today when I have time. Looks interesting.

Brandon,

I would say that stability is the coordianted use of tension to prevent movement. All of the motor systems discussed contribute to that coordination.
 

Matt

Level 3 Valued Member
I will re-iterate my point that reflexive stability is not referring to reflexes, but to the concept of reflexivity (in a philosophical sense).  Understanding that clears up all of this.

(I will reply to Al's comment later).
 

The Scientist

Level 3 Valued Member
Matt,

How does using terminology from philosophy to describe physiology make any sense? There is nothing philosophical being described. Also as best as I can gether reflexivity in philosophy refers to:

"A reflexive relationship is bidirectional with both the cause and the effect affecting one another in a relationship in which neither can be assigned as causes or effects."

This does not describe any aspect of physiology. Cause and effect can always be assigned.

 
 

jgruginski

Level 3 Valued Member
Scientist - I approached the idea of "these signals" as if they were sourced from a different location in the brain distinct from learned-> automatic movements because they weren't conscious actions. However, as I thought about it it makes sense that, for example, the contralateral contractions for spine side bending are just a component of successful side bending learned as a way to fight gravity and not fall over. Same with the stability generated to transfer power from one side of the body to the other or from the legs to the arms or eccentric control of antagonist movements to fine tune the movement or prevent injury.  This firing of the inner unit is just a subconscious component of a previously successful pattern. I need to bust out my neuroanatomy texts and brush up on this stuff. I do love the fact that we have a lot of people here talking at this level.
 

Matt

Level 3 Valued Member
Al, perhaps you’ve misunderstood me. I am not disagreeing with anyone just to be clear.

I’ll just write point form my logic to hopefully be clearer -

From the definition of Reflexive stability – anticipation.

Question: how can a reflex anticipate.

The Scientist – technically it can’t. He’s correct.

Then I was detouring a bit in thinking of the broader context of the discussion, about the causality of a reflex. From this position I had the intuition that the word reflexive doesn’t refer to reflexes being involved in the physiology. But instead, and I should have tweaked earlier – in philosophy reflexive has a particular meaning. This meaning fits perfectly with the behaviour we are discussing.

Reflexive stability – where the muscle acts – it acts locally (as if it is acting on itself) to provide stability for the whole movement.

So the definition is not trying to describe the physiology of the process, in that it is not referring to reflexes. Rather it is a concept about the stability. So if I can quote Pavel – Simple and Sinister.

So all what The Scientist has said is correct – and he would be able to explain the how’s to me/us about what’s involved with the physiology. Yet I am claiming the definition is a simple one, perhaps confusing because the objects for which the concept is applied to involves to reflexes, yet a brilliant one and a precise definition of the process involved. Whoever coined the term is/was brilliant
 

B.Hetzler

Level 3 Valued Member
Scientist - What exactly are you looking for in your original question?  You posed a question and have shot down or countered almost every explanation or suggestion that has been made.    Not trying to be abrasive, but I feel this discussion could keep going in circles so I'm just trying to figure out your "why" behind the question.
 

Matt

Level 3 Valued Member
If it's not clear - the reason it is (or why I understand it is) brilliant is because it is doublely reflexive (it being the stability).

Reflexive in the true (philosophical) meaning of reflexive.

But then reflexive in that it involves reflexes (other "things" can be reflexive but not involve physical reflexes).

So it just so happens it is reflexive squared - and if the originator of the term saw that and called it that intentionally he/she is brilliant.

 

Brandon - thanks for your contribution too - you seem to know your stuff and I've learnt a lot from your posts in this thread.

 
 

The Scientist

Level 3 Valued Member
Brandon,

I was asking for an explanation of the term given that it does not make any sense physiologically. The thing that I am now looking for is for the term to be changed, or at least for it to be acknowledged that it is incorrect, but being retained in spite of that. I really am not trying to declare authority here, but I am a physiologist, I have a doctorate in the field, and am a professor who teaches the subject. I really do have a good handle on the subject. Again, this is not to badmouth the training being advised here. I think it is great. There are just some misunderstandings about the underlying physiology.

Matt,

I realize that I am not going to get through to you. You are free to make up whatever you want to convince yourself that you know what you are talking about. This is not philosophy and never will be.
 

Matt

Level 3 Valued Member
Honestly Scientist, I can say the same to you.

I am not making up "whatever I want" for a start.

What do you want to "get through to me"?  What don't I understand about what you're saying?  If what I have written is not clear, I have actually listened to you and have agreed with you on the physiology.  Yet you are the one who doesn't understand the term reflexive, you admit that it doesn't make sense physiologically, yet you are close minded to a genuine suggestion of an understanding of the meaning which both makes perfect sense from the definition of the terms, while also not relying on the physiology (which should satisfy you on both levels!).

Perhaps I am not going to get through to you - I say that as I am yet to hear from you that you actually understand what I mean.

You will perhaps - maybe over a drink when you are relaxing.  Until then I am not wanting to degrade this discussion with an argument that is starting to get personal.
 

Matt

Level 3 Valued Member
Perhaps I am not being clear so I will try again to explain what I mean.

Firstly, as Brett first stated, quoting Gray Cook, reflexive stability involves:

From Movement by Gray Cook – “stabilizers control movement in one local segment while movement occurs in another, or they create supportive tension within multiple global joints.  Their role is to not move in the presence of movement.  They should therefore be trained to produce integrity, alignment and control in both static and dynamic situation.”
….”the contribution of stabilizers can change throughout the range as well, performing a static role in one phase of movement and a dynamic role within another plane.”
“…true authentic stability is about effortless timing….”

(end of Gray Cook)...

 

The stability is therefore not the action of a reflex - the stability refers to individual muscles (one local segment) increasing their internal tension.  THIS IS A REFLEXIVE BEHAVIOUR - by definition of the concept of reflexivity (yes, from philosophy but that is irrelevant) - the muscle increasing it's own static tension.

THEN - a group of muscles all doing that - individually - can provide global stability (not reflexive so just plain stability - and what Gray is referring to when he says multiple global joints).   This stability then allows the correct joint centrification/alignment to then allow the prime-mover muscles to create efficient and fluid movement.

So the local tension (reflexive stability) must be, as Gray says, playing the role of "not moving in the presence of movement" - it is just a change in their tension.

They must do this first to provide the context for stability of the joint and then movement.  Their behaviour is local ie. them acting as individual muscles independently,  but as a whole provides a stability which is greater than the sum of the parts (ie. the parts being the reflexive stabilisers).  (They can do this because there is a global control "program" organising everything as a whole ie. the brain).  Because they must do this first -  true authentic stability is about effortless timing.

So the reflexive stability must come first.

YET the stability these muscles produce is called reflexive because they "act on themselves" to change their internal tension SO TO SPEAK (Scientist or Brett or Brandon may be able to put that better physiologically).  As Joe (and others)  has said - it only needs to be 10% MVC - not a large change.

The term reflexive has nothing to do with reflexes in the pure sense of the definition of reflexes - a sensory receptor, nor the physiology of the action of the muscles.

Therefore it is, from my understanding (just given), a brilliant term, and explicitly precise (which is what Al correctly argued is essential) in describing what is happening, and doesn't need to be changed.

 

 
 
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