A clarification on "reflexive stability"

Zach Ganska

More than 300 posts
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Every time I think I'm out; they pull me back in....

Scientist,
I follow your argument, however many of the statements you made sounded contradictory to what I was taught as an undergrad in college, so insomnia and curiosity has lead me to pull out my old texts and brush up on the subject.

Brett, Brandon, Scientist -

please provide updated texts if the following quotes are outdated and no longer considered valid in the study of A & P. I would be grateful if so as I haven't studied at the collegiate level in a few years and will be doing so at some near point in time.

Scientist-
These are direct quotes pulled from "Fundamentals of Anatomy & Physiology 8th edition" by Martini & Nath (2009), and "Exercise Physiology , Energy, Nutrition & Human Performance 6th Edition" by McArdle, Katch & Katch (2007).  They oppose several statements you have made regarding what a reflex is and is not (emphasis mine).  Please provide academic support of your claims to disprove these sources.

Reflexes are rapid, automatic responses to specific stimuli .........
The “wiring” of a single reflex is called a reflex arc  A reflex arc begins at a receptor and ends at a peripheral efector, such as a muscle fiber......(Martini 448).

Reflexes are classified on the basis of (1) their development, (2) the nature of the resulting motor response, (3) the complexity of the neural circuit involved, or (4) the site of information processing.  The categories are not mutually exclusive - they represent different ways of describing a single reflex

Innate reflexes result from the connections that form between neurons during development.  Such reflexes generally appear in a predictable sequence, from the simplest reflex responses (withdrawal from pain) to more complex motor patterns (chewing, sucking, or tracking objects with the eyes).  The neural connections responsible for the basic motor patterns of an innate reflex are genetically or developmentally programmed (Martini 449).

More complex, learned motor patterns are called acquired reflexes.  An experienced driver steps on the brake when trouble appears ahead; a professional skier must make equally quick adjustments in the body while racing.  These motor responses are rapid and automatic, but they were learned rather than preestablished.  Such reflexes are enhanced by repetition.  The distinction between innate and acquired reflexes is not absolute: Some people can learn motor patterns more quickly than others, and the differences probably have a genetic basis.
Most reflexes, whether innate or acquired, can be modified over time or suppressed through conscious effort .......

Polysnaptic reflexes can produce far more complicated responses than monosynaptic reflexes, because the interneurons can control motor neurons that activate several muscle groups simultaneously

Spinal reflexes range in complexity from simple to monosynaptic reflexes involving a single segment of the spinal cord to polysynaptic reflexes that involve many segments.  In the most complicated spinal reflexes, called intersegmental reflex arcs, many segments interact to produce a coordinated, highly variable response (Martini 450).

The best-known monosynaptic reflex is the stretch reflex, which provides automatic regulation of skeletal muscle length (Martini 450).

Many stretch reflexes are postural reflexes - reflexes that help us maintain a normal upright posture.  Standing for example involves a cooperative effort on the part of many muscle groups.  Some of these muscles work in opposition to one another, exerting forces that keep the body’s weight balanced over the feet,  If the body leans forward, stretch receptors in the calf muscles are stimulated.  Those muscles then respond by contracting, thereby returning the body to an upright position.  If the muscles overcompensate and the body begins to lean back, the calf muscles relax.  But then stretch receptors in the muscles of the shins and thighs are stimulated, and the problem is corrected immediately.

Postural muscles generally have a firm muscle tone and extremely sensitive stretch receptors.  As a result, very fine adjustments are continually being made, and you are not aware of the cycles of contraction and relaxation that occur.  Stretch reflexes are only one type of postural reflex, there are many complex polysynaptic postural reflexes (Martini 452).

General Characteristics of Polysynaptic Reflexes
1.  They involve Pools of Interneurons......
2. They are intersegmental in Distribution.  The interneuron pools extend across spinal segments and may activate muscle groups in many parts of the body.
3. They involve Reciprocal Inhibition.  Reciprocal inhibition coordinates muscular contractions and reduces resistance to movement.  In the flexor and crossed extensor reflexes, the contraction of one muscle group is associated with the inhibition of opposing muscles.
4. They Have Reverberating Circuits, Which Prolong the Reflexive Motor Response.
Several Reflexes May Cooperate to Produce a Coordinated, Controlled Response.  As a reflex movement gets under way, antagonistic reflexes are inhibited...... In complex polysynaptic reflexes, commands may be distributed along the length of the spinal cord, producing a well-coordinated response (Martini 454).

The brain can affect spinal cord-based reflexes

Reflex motor behaviors occur automatically, without instructions from higher centers.  However, higher centers can have a profound effect on the performance of a reflex.  Processing centers in the brain can facilitate or inhibit reflex motor patterns based in the spinal cord.  Descending tracts originating in the brain synapse on interneurons and motor neurons throughout the spinal cord (Martini 454).

Voluntary Movements and Reflex Motor Patterns

Spinal reflexes produce consistent, stereotyped motor patterns that are triggered by specific external stimuli.  However, the same motor patterns can also be activated as needed by centers in the brain.  By making use of these preexisting patterns, relatively few descending fibers can control complex motor functions.  For example, the motor pattens for walking, running, and jumping are directed primarily by neuronal pools in the spinal cord.  The descending pathways from the brain provide appropriate facilitation, inhibition, or “fine-tuning” of the established patterns.  This is a very efficient system that is similar to an order given in a military drill: A single command triggers a complex, predetermined sequence of events.

Motor control therefore involves a series of interacting levels.  At the lowest level are monosynaptic reflexes that are rapid, but stereotyped and relatively inflexible.  At the highest level are centers in the brain that can modulate or build on reflexive motor patterns.

Reinforcement and Inhibition

A single EPSP may not depolarize the postsynaptic neuron sufficiently to generate an action potential, but it does make that neuron more sensitive to other excitatory stimuli, known as facilitation.  Alternatively, an IPSP will make the neuron less responsive to excitatory stimulation, through the process of inhibition.  By stimulating excitatory or inhibitory interneurons within the brain stem or spinal cord, higher centers can adjust the sensitivity of reflexes by creating EPSPs or IPSPs at the motor neurons involved in reflex responses.

When many excitatory synapses are chronically active, the postsynaptic neuron can enter a state of generalized facilitation.  This facilitation of reflexes can result in reinforcement, and enhancement of spinal reflexes.  If a stimulus fails to elicit a particular reflex response during a clinical exam, there can be many reasons for the failure: The person may be consciously suppressing the response, the nerves involved may be damaged, or there may be underlying problems inside the CNS.  The clinician may then ask the patient to perform an action designed to provide reinforcement.  Reinforced reflexes are usually too strong to suppress consciously (Martini 455).

Reflex actions in the spinal cord and other subconscious areas of the CNS control many muscle functions.  Hundreds of hours of practicing a particular skill “grooves” the neuromuscular movements to become automatic, requiring little to no conscious control.  Unfortunately, improper practice can also automate a task to produce less than optimal neuromuscular actions (McArdle 402).

Summary
1. Neural control mechanisms located in the CNS finely regulate human movement.  In response to external and internal stimuli, bits of sensory input automatically become coded, routed, organized, and transmitted to the effector organ - the skeletal muscles.
2. Tracts of neural tissue descend from the brain to influence spinal cord neurons.  Neurons in the extrapyramidal tract control posture and provide a continual background level of neuromuscular tone; the pyramidal tract neurons stimulate discrete muscular movements.
3. The cerebellum fine tunes muscle activity through its function as the major comparing, evaluating, and integrating center.
4. The spinal cord and other subconscious areas of the CNS control diverse muscle functions.  The reflex arc provides the basic mechanism to process “automatic” muscle actions.
(McArdle 414-415)
 

Zach Ganska

More than 300 posts
Certified Instructor
The original post:

"The problem that I have with this is that reflexes are clearly defined phenomena. They are involuntary and predictable responses to stimuli. In the case of the proposed “reflexive stability”, what exactly is the stimulus? Is it being proposed that visual input is the stimulus? Is it proprioceptive input from stretch or golgi tendon reflexes in the surrounding musculature? This would seem to negate the “anticipate movement before it actually moves” part of RS.

To me, it sounds like the “anticipate movement before it actually moves” part suggests that what they are actually attempting to describe is motor learning and patterning. This is a critically important thing for movement, but it really is not a reflex at all."

Based on the definitions the texts I cited provide I would state that your basic definition of a reflex is correct, however it disregards the many different types of reflexes and their inherent interconnectedness in motor learning and patterning, unless as I previously stated my cited texts are no longer valid.

The term "reflexive stability" would thus be correct, I am agreeing with you in that the word "anticipatory" is being incorrectly used in defining RS, and I think this is the root issue that launched this debate.  The material I read and re-read we would be wise to instead make it clear that all our reflexes, whether monosynaptic or polysynaptic are occurring in response to an external or internal stimulus.
 

Zach Ganska

More than 300 posts
Certified Instructor
Scientist-

To clarify my intent in the last posts, not delineating the various categories of reflexes and using other terminology (such as motor control) seemed to distort the discussion and remove the connection between innate reflexes and those we acquire.  My wording initially was not as eloquent as it could have been, and I could see how my phrasing in writing could potentially sound rude and insulting, if so apologies.

 
 

Zach Ganska

More than 300 posts
Certified Instructor
Brandon,

A point I'm fuzzy on.  "Feed-forward stability" to include anticipatory in the definition, good stuff,  especially catching the ball, anticipating it's arrival and moving appropriately. In one of the links Brett posted (first nih one I believe) the author stated that separating "feed-forward" from "feed-back" can often be unclear and debated upon.

In the example of a ball being thrown, or the other examples given of feed-forward stability, isn't the stimulus still present first?  For me to initiate my "ball catch" movement pattern I have to be in an environment that gives me the stimulus to do so yes?  In that case the presence of a ball, or being in an environment that I have previously been in when catching a ball such as a park, makes me "anticipate" the possibility of catching it at some point.

I'm picturing that one would be completely neurotic and move very poorly if truly anticipating activating all their learned behaviors at any point in time without a stimulus priming them to do so.

So what state is needed for true feed-forward stability?  Moving or being present in a "flow" type state such as is sought by martial artists, "no mind" I believe is the translation from the scene I'm thinking of in Last Samurai.  Or am I misinterpreting in some way that can be cleared up with another example?
 

Brett Jones

StrongFirst Director of Education
Master Certified Instructor
Beast Tamer
Sean,

you are still stuck on what you can "feel" contract etc.... and that is why you still struggle with this concept IMO

 

Plentiful reference has been provided and the terms stability, motor control and reflexive stability (a subconscious response to a stimulus) have been worked over pretty well  and apparently "reflexive motor patterns" etc.... are established terms and definitions

So what were we arguing about?
 

The Scientist

Triple-Digit Post Count
Matt,

First, I apologize for being so harsh. Second, this is thing that I am saying you are wrong about. : "YET the stability these muscles produce is called reflexive because they “act on themselves” to change their internal tension."

The only time a muscle can reasonably be said to "act on itself" is locally through the stretch or tendon reflexes, and even this is a stretch because that information is modulated through the spinal cord. My point is that when a person trains a movement, the regulation of that movement is through changes in the brain. So a muscle is not acting to increase its own tension. Only the CNS can do that. This is why I think reflexive (even the non-physiological definition) still does not work.

Zach,

There is a lot to tackle here (but I am impressed with your thoroughness). I had never heard the term "acquired reflex", and a pubmed search shows that it doesn't get used in research literature. I had always thought of these as "conditioned reflexes" (Pavlov and his dog), where a new stimulus (bell) is piggybacked onto an existing stimulus (smell of food), but the response (salivate) doesn't change. The reaction when driving a car – I would call that a learned motor pattern.

At this point, it seems like we are wading into territory of confusing and unclear terminology. I think it was a good discussion, though. I'll come back and do some more thorough reading later.

 
 

Matt

More than 300 posts
Hi Scientist – no worries. I don’t mind my ideas being severely punished. Thanks for considering it – and I agree it is the “acting on themselves” which I wasn’t sure of and which I hoped someone else more knowledgeable might be able to describe it more accurately and then see if it works or not with what I was saying.

I was doing a bit of reading yesterday and it seems to be a loosely used word. The context of its usage changes quite a bit. Makes me believe it had a specific original use which has perhaps then became more widely used out of context though still conveying roughly an idea. It would be interesting to find the first usage.

I was thinking (my post on my job etc), before my tangent, that internal stimulus from the brain could be a possible explanation for the use of reflex. Bit like what was said in Zach’s compendium posts.

From what I was reading they use reflexive in the sense of “innate” or “subconscious” – a baby learnt something reflexively, it wasn’t taught by written instruction or example etc.

Anyway – be interesting to know what you or others conclude
 

Al Ciampa

Quadruple-Digit Post Count
Certified Instructor
A great discussion... it certainly this idea clearer for me.

Thanks to all who participated.
 

Steve Freides

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Staff member
Senior Certified Instructor
Would it be fair to say that a continuum exists, with completely automatic actions at one end and purely volitional at the other?   So many terms have been used in this discussion: reflexes, acquired reflexes, stretch reflexes - I'm curious if we can agree that there are several points along the way between automatic/unconscious and volitional and that looking at them this way might be a useful model.

I realize that the mechanisms by which these things happen in the body and brain may seem quite distinct to those more deeply involved in kinesiology than me.   I am looking for the 50,000 foot view and to perhaps place some of the specifics of our discussion at points along the continuum.

-S-
 

Zach Ganska

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Certified Instructor
Steve-

I think this thread, like many other ones in the past, demonstrate first they need for us as individuals to work on continuing to learn and use the established scientific principles of movement and strength.  I haven't seen volitional in any academic writing I've been exposed to on the subject so we'd be better to reframe our individual thinking by expanding on our perspective and ensuring we are all speaking the same language, which obviously was the motive behind this threads beginning.  It seems to me that conscious movement is built with a composition of reflexes, the continuum then being the complexity of the timing and motor control involved in coordinating the vast number of reflexes to move in the way we desire.

Rather I think it's better to reflect on how our learned motor patterns came into their current state of being, arising from our brain learning to coordinate reflexive muscle contractions and then we can refine those that are dysfunctional using the principles of the FMS.  It's clear that those patterns we consciously initiate are the product of our brain initiating the timing coordinated effort of more "reflexes" than we can calculate to carry out the "squat" or "walk," etc. programs.

 

 

 
 

Steve Freides

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Zach, I'm trying to speak non-scientific English and proposing a continuum from purely automatic responses to what seems to me the other extreme, which I called volition all but we could also call voluntary or feed-forward.  Volitional - things like, "I am going to grip the bar as hard as possible, a conscious effort to engage muscles.

-S-
 

Zach Ganska

More than 300 posts
Certified Instructor
Steve,

I understood your desire to want a voluntary - involuntary continuum, it doesn't exist though.  Conscious movement patterns require a coordinated effort, "crush bar" thought/stimulus initiates a chain of reflexive precursors before my hand touches the bar.  Acknowledging this will in fact highlight the reason this community says "strength is a skill," "practice," and emphasizes the execution of one perfect rep over the volume of reps.  It will clarify feed-forwad strategies, hyperirradiation, etc. for beginners over other training language used in other circles that does not mesh with our paradigm.

I'm not saying discussions have to begin with muscle spindles, nerve innervation, etc., I don't think it's too much for everyone posting to have a working understanding of mobility, stability/ motor-control, patterning, and understand that applying the skill of strength is built on top of this understanding of movement and then apply these to a push, pull, hinge, squat and carry.  This seems inline with our principles that we uphold in the StrongFirst community.
 

Zach Ganska

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Certified Instructor
Steve-

Have you read "Movement Restoration" yet?  It clearly describes the neurodevelopmental sequence we all go through to learn movement, having distinct postures and movement patterns that progress each human from entering to the world to being able to move in the gait pattern.

The principles and concepts are laid out in plain english, this book is the best that comes to mind to arrange movements by complexity, and how we can regress higher level movements to address the weak links along the FMS model.
 

Matt

More than 300 posts
Hi Zach,

 

Do you mind me asking - how does Movement Restoration fit in with Movement by Gray Cook - is he extending those principles, or was pre-Gray cook or?  I was thinking when you mentioned it in the other thread (original thread by Jeffery) that it seemed like an excellent book, yet I wondered, as I believe a lot of people have taken the ideas of Movement by Gray Cook and have reapplied them inaccurately.
 

Steve Freides

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Zach, I have it, started reading it, but haven't finished it.  My favorite part so far is the description of Brett Jones. :)

-S-
 

Zach Ganska

More than 300 posts
Certified Instructor
Matt-

Movement Restoration expands upon Movement by Cook.  It'll clarify the Movement principles, why they're ordered as they are from the developmental sequence we all go through to learn to move, and what is occurring during an FMS screen. It's like the "Movement" prequel, not of the three awful Star Wars variety, but rather the X-Men. :)

Brandon is now one of the featured FMS models in their new corrective videos so I feel safe in saying it's fully endorsed by the powers that be at FMS.
 

rambodoc@gmail.com

Triple-Digit Post Count
Hey, Scientist!

I think you raise an important issue.

I won't add much to the chatter, save to ask one question and make one point:

Why not consider the phenomena described as 'reflexive stability' as a conditioned reflex? In fact, involuntary movements that become ingrained by motor learning are conditioned. Right?
 

B.Hetzler

Triple-Digit Post Count
We wrote Movement Restoration with the full support from FMS - It all started with a meeting between us, Lee and Gray in Chicago 5 years ago.

Scientist - I also am not a fan of the term reflexive stability.  But, it is a commonly referenced term and it is an accepted term in rehabilitation world and the corrective world.  I applaud your effort, but anything gained here in regards to changing the terminology will be hard pressed to lead to changes elsewhere.  The important thing is "it" (whatever it should be called) happens and when applied at the correct times can have drastic changes in people.

 
 

Matt

More than 300 posts
Thanks Zach (I like the prequel rating system :)), and thanks Brandon (sorry I should have asked you too)!  Definitely seems like a good Christmas read.
 
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