I see what you are saying, but I have to think very carefully about whether this fits. To me, it seems like the goal of the kind of training being advocated here is to increase a person's stability during conscious, voluntary movements. Also, RS has been defend as anticipatory. A reflex must have a clearly defined stimulus, and that means it cannot possibly anticipate. Also, the response must be clearly defined. If it was truly a conditioned reflex, the person should not be able to modify the response, even if they want to. It just doesn't seem like that fits, and I think motor learning is a better and more accurate description. Your brain can anticipate which motor plan is needed, and then modify it if necessary during the activity.
I realize that I am unlikely to change anything. If it has not become obvious, I love hashing things out just for the pleasure of exploring the topic. If it leads to a positive change – even better.
In the spirit of exploring the topic (while not being redundant I hope) - I would wonder about a few questions :
Firstly, we are discussing just reflexive stability or? So one question, that may help define the reflexive nature of reflexive stability, is what other types of stability are there? Is there a stability where a specific muscular contraction directly stabilises something else for example? Such as: I can hold my own weight upright via postural muscles, or I can use a walking stick. Different stability, similar if not the same outcome.
I wonder too : consider what happens when a muscle gets injured. Instantly the brain, via some complicated feedback, creates a new motor plan. This hasn't been ingrained to become a reflex (though it eventually does - which is the interesting second half of this question - why does this reflex remain when the stimulus is no longer present ie. the injury or pain). The stimulus is the pain etc. so it could be a reflex response, yet it is a fully functioning immediate motor pathway that just works with no anticipation (if so then you wouldn't have gotten hurt). Normally when considering this question we look at babies who are a convenient blank sheet in terms of neural behaviour/learning. Yet for anyone, child/adult - this creative alternate neural patterning can be activated on one instance. Apparently the new protection motor plan can be different for each person, yet I would imagine, like most things with the body, it is the most efficient plan for the specific problem (so there is not really an element of randomness to it). So - stimulus could be pain, but conditioned response varies meaning sort of like a reflex.
Difference in the bodies reaction to an internal stimulus like fear v some activity while dreaming could also help clarify what role reflexes have in stability and therefore movement.
Wonder about babies moving in the womb (so minimal external visual stimuli). I guess a lot of that could be random - and it would be learning from that I guess via feedback. To get a random movement however, would still need something to be stabilized (reflexively) to allow movement somewhere. So it can't be a reflexive response ie. a cause-effect reflex-like behaviour.
The intent therefore is a (THE) crucial part of movement, where that comes from and how it is expressed via movement. Intent doesn't seem to work with the concept of a reflex (like act v react).
Fascinating! Something so simple, taken for granted.
Let me try to clarify based on your response and I'll listen to what you have to say.
When I say feel GMed contract when you stomp or step, I mean put your hand on the muscle and feel it twitch, ie palpate or whatever they call it, as opposed to trying to feel it in your brain.
I think this might be a synergistic contraction to glute max.
Anyways, it happens and the twitch can be felt objectively, right? Glute med is providing more stability to the leg by firing?
And this is where I don't understand the "learned motor program" lingo. I don't see how this automatic contraction that happens when people walk (barring a chronic muscle imbalance) is not a reflex of some kind - or perhaps it is some kind of combination of both with learning to walk as a toddler, etc.
I'm amazed this has lasted on long enough to get to 6 pages. I'm more amazed that I am again responding to this. Scientist - you are coming at it from your perspective where everything is black or white. Everyone else - you are trying to convince scientist that his view needs to change (albeit very politely, but that is what it boils down to.)
Here is the underlying problem - Movement isn't a cause and effect type action. Movement isn't a A+B = C type action. Movement is a behavior. And just like any behavior it changes constantly. Everything we do either strengthens the behavior or changes the behavior. In the end, it is an ever changing sea of gray. That is why the best in the industry keep talking about movement principles (just like here at SF, things that stay true no matter what). Unfortunately, the conversation gets sucked downward because those that argue the movement principles are arguing their principles of movement (not just semantics). How does every system, muscle, cell, and synapse in the body work together to generate this movement behavior? It took 10 years (I believe) to map the genome of a 1 celled organism. We have more than 1 cell - it's not going to happen in our lifetime. Until then, embrace the gray and stick to the principles of movement.
@ Brandon Hetzler: you have chosen a poor example as E coli's genome has been sequenced in the 90s whereas the human genome was sequenced over a decade ago.
I applaude the effort of the scientist. His issue is the correct use of established terms so that everone can participate. If one makes up terms or even a whole system we have a guru as he is the only one knowing these terms. Using a precise language allows the exchange of knowledge even between different fields. Thus it enhamces the progress of understanding (in this case) movement related phenomena.
You're game Brandon - you've potentially set off another 6pages of intense discussion! Good.
To me the difficulty people are having is coming from using a linear causality to try and understand movement, which is sort of understandable from a scientific point of view/reasoning. Similar to what you've just said (cause and effect).
“For example, the reflexive response 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. Although neuromuscular control underlies all motor activities in some form, it is not easily separated from the neural commands controlling the overall motor program. For example, in throwing a ball, particular muscle activation sequences occur in the rotator cuff muscles to ensure that the optimal glenohumeral alignment and compression required for joint stability are provided. These muscle activations take place unconsciously and synonymously with the voluntary muscle activations directly associated with the particulars of the task…”
“Activation of motor neurons may occur in direct response to peripheral sensory input (reflexes) or from descending commands initiated in the brain stem or cerebral cortex, or both.”
Should we contact the authors and correct them?
reflexive stability might not be an ideal term but as I posted multiple links to studies using that term so the "industry" has already adopted it apparently
There are two senses of the word "science" that might help here. They both apply to movement.
The first sense of science is what is self-evident, basic, agreed to by everyone, and black and white. Glute maximus is the prime mover in hip extension. The wrist flexors simply cannot extend the hip. No one disputes this. Not only is it true because a group of people agree about it, it is something that is immediately verified by the senses. My gm tightens up when I extend my hip. Yours too. No one who extends their hip will do so with a gm contraction. This is a plain fact of movement - a simple example of pulling. What pulls the leg back? The shortening of the gm (how the gm does this exactly gets into the second sense of the word "science"). There is a necessary cause-and-effect relationship between gm and hip extension. It is like knocking a cup off a table. If you didn't knock the cup off, the cup would not have fallen off. Cause and effect.
The ancients, especially Aristotle, did not brush over this kind of science whereas the modern mind does (with good reason - its rapid advances). And this is why these kinds of discussions feel like a walk through sinking quicksand.
The second sense of science is not black-and-white.
How hip extension happens exactly is what segues into the second sense of the word "science." No one disagrees THAT the contraction takes place, but there is plenty of disagreement HOW the contraction takes place. (for example: http://en.wikipedia.org/wiki/Muscle_contraction) This is the science that depends on experiments, tearing apart, material analysis, measuring electrical charges, discovering genomes, etc. This is the kind of science that is grey.
The first kind of science is accessible to anyone. The second is only accessible to experts.
We should embrace both, the black-and-white, and the grey. Know that there are some things that are certain and known, and others that are harder to wrap your head around and take time and patience in the lab/analysts to flush out.
I believe the black-and-white aspects of movement that is easily accessible to average folks goes a very long way in improving movement. I've experienced it in myself and others (I'm told).
“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.
Maybe the g-med stomping example is an example of this.
Not sure why you said that, I think we are in agreement here.
I lost that muscle and lived with chronic muscle imbalances for over a year and now very much appreciate the objective feel of it working, and moreso not living in pain and having to walk upstairs sideways.
I’m not answering for Brett of course – but if I was to read what he posted :
reflexive response – is just that – the reflex action when you tap your knee etc.
But that is not reflexive stability.
Interestingly they define stability as ” One additional physiologic term requiring attention in a broad context before our specialized discussion is stability. Stability is defined as the state of remaining unchanged, even in the presence of forces that would normally change the state or condition.3 It has been further described as the property of returning to an initial state upon disruption.4 With respect to joints, based on the above definitions, we define stability as the state of a joint remaining or promptly returning to proper alignment through an equalization of forces.”
Sorry about the weird cut and paste - if it comes out weirdly.
But if they define stability as being stable or returning to stability, then reflexive also may have a non-literal (to the everyday schmo) or non-obvious meaning when used with stability.
BUT – they then go on and define neuromuscular control and joint stability, and to my understanding this is the closest conceptually to “reflexive stability” as we here agreed are talking about. They give a good understanding, as Brett posted.
They do also mention directly “reflexive joint stability” and how proprioception has been incorrectly used as a term to define it.
They never seem to question the concept of reflexive stability
@ Leon Kaz - (http://www.humanconnectome.org/) My bad - While I was typing my last response I was actually training some athletes and not trying to become an interweb expert. I had to type from memory during one of their water breaks. I said genome, meant connectome.
I also posted a nice article from a blog on my facebook page that was on the subject of my last post - not going to link to my fb page. Here is the direct link to the article I shared (http://thegaitguys.tumblr.com/post/103571941844/toe-walking-in-children-do-you-know-what-you-are).
As far as Brett's quoted " after an imposed perterbation". If they eyes are opened and the individual can see what is going to cause the perterpation, there will be an anticipatory response prior to the perterpation (almost like a learned behavior, hmm). Nerve impulses can travel up to 89 m/sec - much faster than human movement. An anticipatory output can occur in milliseconds. Even if the eyes are closed, the tactile stimulation can do the same-albeit the output might not occur quickly enough to affect the movement. Why is this so hard to understand. Brett has been spot on with his points, provided research to back his points and yet everyone is STILL arguing.
In elementary school all the boys would have a literal pissing contest when we went to the restroom - who could stand the farthest from the trough and actually hit the inside of the trough. We would then go back to class to learn. I think it is time to go back to class on this one.
you are arguing one point off of a definition I did not provide but as Brandon noted "anticipatory" does not negate the concept of reflexive response or reflexive stability but rather can be part of the discussion
I know everyone can read it for themselves, but the article Brett initially posted talks about this too. I was going to mention it yesterday but couldn't read some of the references. Yet :
In some circumstances, a combination of both feedforward and feedback control exists, such as during the maintenance of postural control.6 Additionally, consider the situation in which a subject watches a tester trigger a device that induces a joint perturbation. Many subjects will naturally ‘‘tense up’’ when they see the tester beginning to push the trigger before the perturbation. Whether the muscle activation before the perturbation reaching the joint is the result of feedforward or feedback control remains controversial. For this reason, the term feedforward control has been recommended to describe actions occurring upon the identification of the beginning, as well as the effects, of an impending event or stimulus.4,5,7"
Brandon and Brett have put that in their own words too.
I was thinking of a similar thing in an earlier post when my response to my anticipation of an event was much more than the direct stimulus (my eye reading a number on the screen).
To be fair, I can also see how Scientist can claim they are learnt motor patterns, not reflexive (where a reflexive response must always at all times be a response from a nerve being stimulated, not anticipating the stimulation)? A baby or an ignorant newbie learns these responses from direct stimulation then anticipates. YET a baby has a direct stimulus (gravity) from day 1 and so straight away is learning to "control" it's huge range of mobility (ie. stablise reflexively). This is probably talked about somewhere in the paper Brett referenced or it's followup.
Something that surprised me - these concepts and terms are over 100years old, involving a Noble Laureate. The paper Brett referenced outline some changes in terminology today, yet you'd think the discussion we're having has been had over and over already?