Monday, May 19, 2008


I have been doing some research into the arthrokinetic reflex. This directly relates to one of the foundational concepts behind the dynamic joint mobility of Z-Health.

A snippet of some of my rough, rough, rough draft paper:

Critical to performance, the sensorimotor system regulates the control and force applied by skeletal muscles to the bones and joints through the constant interplay of sensory and motor neurons. If at any time sensory feedback is altered abnormally, motor control of the muscles will be adjusted and altered as well. Hurley et al (27) stated that a joint must have normal mobility in order for the muscles which cross that joint to function efficiently. A muscle which crosses or attaches to an immobile joint will be inhibited by sensory feedback from free nerve endings located within joints and ligaments(mechanoreceptors) known as the arthrokinetic reflex (AKR). The AKR (6,21,23,45) is an inhibition of muscles surrounding or attaching to a joint that is injured, hypomobile, or exhibiting faulty arthrokinematics (43). The AKR may not only effect local muscles around a particular joint, but also more remote muscles, including those on the contralateral side of the body (22), which results from the multisegmental organization of mechanoreceptor afferents within the neuroaxis (21). The articular mechanoreceptors located within joint capsules regulate the AKR (5,8-11,43,44).

The importance of mobility cannot be overstated...

One more thing:

Stability should be taken out of the training world "vernacular". I am not sure what the hell this means anymore. This topic came up at the College Strength and Conditioning Coaches Association conference that I recently attended in Nashville, TN. (Gray Cook and Robb Rogers' presentation, which was good, but irritated my bad tooth when the overhead squat photos appeared again... ahhhhhh!!!!)

A big reward for anyone who can explain this one to me.



Mike T Nelson said...

Good stuff man! I think more will catch on to the importance of the arthokinetic reflex soon since it has such huge ramifications! Thank you Dr. Cobb!

Stability can just be replaced with "coordination" in most cases. Thanks for Frankie Faires for pointing that out to me.

I have some good stuff on "super stiffness" at my blog now too. Another bastardized topic---hehehe. So I got it from a research in McGill's lab to clear it up.

Rock on
Mike N

Aaron Schwenzfeier said...

Thanks Mike.

Coordination is absolutely the word. Motor control is lost in all this stability talk. I really don't know what stability means anymore.

"Super stiffness" is just another form of coordination.

Courtney said...

Great post!
Would you mind posting some of the references??

Anonymous said...

I understood the stability/mobility concept, but was unable to explain it until now. Use the toe touch as an example, standing vs. seated. If both are limited (subject can't touch toes), it's a mobility problem. If they can touch seated, but not standing it's a stability problem. Here's why:
You should be recruiting certain muscles to maintain pelvic stability while performing the standing toe touch. If the proper muscles are being recruited, the subject will be able to maintain stability and touch their toes. If they can't touch their toes, it's because they have to recruit other muscles (hamstrings, etc.) to make up for stability (compensate) that would be lengthening in a normal movement pattern. Thus, a person unable to touch their toes would show a faulty movement pattern in this movement. We learn these compensations over time from bad habits (i.e. posture), activities, sided dominance, etc. Cook's Functional Movement Screen is based on finding these incorrect movement patterns and then using corrective movements, instead of isolating certain muscles that may be tight or not firing.
The toe touch example comes from Gray Cook's Secrets of the Hip & Knee video.
Hope this helps.

Ryan Hagenbuch

Aaron Schwenzfeier said...

Hi Ryan,

Thanks for checking out my blog and the comments. I always appreciate a good discussion.

I understand the toe touch concept and that compensations may occur in a situation such as the one you presented. It makes perfect sense, thanks for the write-up.

Yes, it is a pattern issue, I completely agree. I am familiar with the anterior and posterior weight shift and the reflexes that fire with each. But I still quesion where stability comes into play to fix the toe touch? (I'm pretty sure I know what they are saying, but I am just being the devil's advocate with this one)

Does doing some bridging("stability" work), bands, and/or activation improve the toe touch? Maybe, but not necessarily, it still is a pattern that has to be corrected or trained if you will. Does the toe touch require great ability to move well?

Elevating the toes helps inhibit the plantar reflex, creating a posterior weight shift. A towel or ball squeezed between the knees helps activate the anterior chain muscles, reducing the extensor activaty, and the overhead arm reach helps turn on the deep core muscles. All this will hopefully help restore the toe touch pattern. Again my question is, is it really a stability problem? or is it just a neural pattern issue?

My main disagreement comes with the use of the term stability. I think too often when someone hears stability, the thought is to resist movement, tighten-up, or "lock down" a certain joint or body area.

...again that is why I like the term coordination much better... maybe I am just so sick of hearing the word stability.

Here's another question I have; my daughter who will be 2 years old in 3 weeks, can squat deep (perfect), does she have better "stability" than the guy in the photos? I would hope not.

For the overhead squat, does pulling the athlete into the mistakes create the "stability" needed for a correct pattern? Maybe at the moment, but what happens when the athlete comes in "cold" one day after a month of using the bands and the "stability" exercises?

Is the pattern there without the pre-exercises? Can the athlete "muscle" themselves into the correct movement, that my daughter can do effortlessly?

Mobility first,"stability" or better yet, coordination second.

Additional thoughts: The FMS focuses on movement patterns, but the methods to get there seem to go through activating or adding tension to groups of muscles or turning on specific patterns. To me most people carry enough tension the way it is, does adding more "stability" work, bands, squeezing, flexing create more efficient movement? Tension requires some level of activation of the muscle and this requires more energy than a relaxed muscle, most of our daily movements should not require excess amounts of energy expenditure, hence efficiency.

Coordination/motor control is key and really can only be effectively trained through good mobility training.

Ryan, sorry for the rambling response, hopefully it makes sense. I would love your thoughts/arguments. Thanks again for the comment.

I would love any additional insights, comments, and arguments...


Anonymous said...

Responses to some of your points:
1. I would say the toe touch doesn't require great ability to move well, but the ability to move well (properly) is dependent on the proper execution of the toe touch.
2. I would have to say it's a stability problem because of a neural pattern issue.
3. I think coordination would be synonymous with stability in this case (I understand what you're saying).
4. Your daughter doesn't have better stability because she lacks strength and control which Cook states is the optimal situation because only the correct neural patterns are reinforced when they learn body control through trial and error.
5. Regarding the overhead squat, Cook does recommend a warmup before testing the movements. I would say that some days might require more movement prep than others, depending on test results. He states that you won't need the corrections forever, just until the pattern is corrected. Of course, other incorrect patterns could arise during this time.
6. Cook and I agree that mobility should come first and then stability/coordination.

I can only speak for myself about my use of the corrections and the positive effects it has had on my training. I just use several of these as my movement prep before working out.
Someone you might want to consider speaking with is Brett Jones. He has experience with Z Health and the FMS.
Great discussion. Thanks!

Aaron Schwenzfeier said...

Good stuff Ryan!

1. agree, but movement is dependent on numerous movements.

2. I think "stability" is just a bad word, but I agree on neural pattern issue. What causes neural pattern issues? Immobility, both from a joint perspective (arthrokinetic reflexes, "motor stupidity") and from habitual daily habits/patterns (connective tissue adaptation, muscle inhibition).

3. Yep, probably saying the same things.

4. Does prove you don't need stability to get into the position, but coordination to control it. Saying the same things, but I don't think stability is the route to go. The picture with the guy lying on his back still would be able to hold that position upright if the picture was rotated. (center of gravity still falls behind him, as does the guy with good looking OH squat when position on the floor. The floor does not allow for shoulder mobility and thoracic extension to be shown. Plus the bad squatter's ankles are still missing adequate mobility. A half-inch less ankle mobility may not visually appear much different, but get's multiplied the higher up you go on the structure. Think: half a foot variation on one side of a building probably won't effect a 2 story house, but will cause some real issues for 30+ story building.

5. The thing with the FMS is that they are patterns... learned ones. Good baseline, but may not transfer in many situations outside a weightroom.

6. Yes, mobility is the window for everything... (guy in squat photo: seems to have stiffness, would improved mobility turn that stiffness into "stability"?

The thing I like about Z-health is that it doesn't confine movement into a few selected patterns.

Would love to hear Brett's thoughts.

Thanks, Ryan!

Anonymous said...

I e-mailed him to take a look at this.


Aaron Schwenzfeier said...

Look forward to what he has to say...

Brett Jones said...

Ryan pinged me with an email to come over and check out the posts here so here I am:
"firmness in position" was one definitions I found to be of use when I looked to find if there was any clarity to be found in the use of the word stability - I have had this discussion with many people Z and non-Z.
Yes any movement issue - coordination,patterning,"stability"or mobility or AKR is neurological and the corrective strategies in the FMS try to re-pattern faulty movements by "triggering" the correct pattern by Reactive Neuromucular Training - basically you feed the mistake. If the knees are caving in during the squat - cave them in a bit more so that the proper pattern can be triggered - it works and have used it many times and it is just like Z - you have to get your reps in on the corrections to have them "stick" but if you are targeting the right things then you get pretty quick results.
Now if the knees were caving in on the squat I would also use some outside toe pulls etc... I integrate both.
The overhead squat - is a testing position that creates the most restrictive position so that mistakes are easy to see and so that someone will have the highest level of movement is they can hit a 3 in the test positions. These are not training or sport positions - they are human movement positions that everyone athlete and non-athlete should have access to.
There are those certifications out there that use a simple algorithim to provide answers based on mistakes during the deep squat - if the arm pitch forward you are told it is "tight lats" - the photo shows that the individual does not have tight lats but rather another patterning issue - that is the point of the photo and if the "core" (HEAVY quotation marks) does not trigger appropriately during the squat than the squat pattern will suffer and yes it could be because of a pronation issue at the ankle etc...but if they can lay on their back and get their arms overhead - it isn't tight lats.
As the AKR indicates - improper triggering of the "core" and motion at the lumbars at a time when they should display coordinated "stability" of their position could turn off any number of muscles/patterns.

Stability vs. Mobility - Coordination vs. Superstiffness-
it in some ways becomes a debate in semantics - one group doesn't like one word for various reasons but Coordination meaning coordinated bracing under load or movement that maintains joint position while allowing efficient movement and/or transitioning through positions is another person's stability.

Aaron - have you been through the full FMS course?

Aaron Schwenzfeier said...

Hi Brett,

Thanks for stopping by, and for your feedback.

I absolutely agree it is a case of semantics. I guess I just think stability gets people thinking to "tighten up" or resist movement and with movement that is the last thing we want to think about... usually.

My thoughts are still that in order for muscles to function and to be able to create proper patterns, the "clear drawing board" of mobility must be there first. Just as a young child has to be able to develop stability.

Another question: How did the guy in the second photo lose the pattern when he had it at a very young age? My guess is because of a lack of quality movement, mobility... thoughts???

From my perspective the guy in the photo still lacks the amount of ankle dorsiflexion as the guy in the first photo. Also you can see the overuse patterning of limited dorsiflexion which has led to limited knee flexion. Anterior weight shift creating increased workout load on the knee extensors.

Maybe not limited by lats but limited in shoulder and thoracic mobility. On the good overhead squat photo, if you draw a straight line from hands to back of the hip, there would be a space, whereas the bad squat creates a pretty straight line from hands to back of the hip. The lying on the ground photos do not show this, as the good squatter would have to arch his entire back and head to replicate the standing squat movement.

To me all of those issues seem like mobility ones, not "stability" issues. ????

Other questions:, does fixing the pattern, such as an overhead squat, then transfer to all other forms of dynamic mobility?

Does improved mobility around all joints create a larger buffer zone in which to transfer/perform any given movement?

My thoughts are develop the mobility first, then you can have the ability to work "stability" through any and every movement.

Couple notes from Gray Cook's presentation at the CSCCA conference:

-if the joints don't move, you don't have proprioception.

-prime movers vs. stabilizers= if mobility is there, coordination will develop stabilizers.


I have not done the full FMS course but would love to. I have used the FMS and still do. We use it with our athletes, gives a lot of good feedback. Would love to learn more for sure.

Most of this is just thinking out loud and trying to make sense of everything, so please don't take this as any offense to the FMS and it's concepts.

Again Brett, I appreciate your input, and would like to hear more...

Thanks again for the response.

Mike T Nelson said...

Good discussion here!

My take aways so far "Does doing some bridging("stability" work), bands, and/or activation improve the toe touch? .....Does the toe touch require great ability to move well?"
---what you are asking about is transfer. Does the new learned skill transfer to anything else?

"Other questions:, does fixing the pattern, such as an overhead squat, then transfer to all other forms of dynamic mobility?"

--I wonder the same thing. For some athletes, and overhead squat is specific and for Ethel that has a hard time sitting down, it is not specific. She probably has not done a single rep in her life, so she is going to suck at it on rep #1.

You really want to know if I get her to do an OHS, does that improve anything else? If so, how efficient a use of my time is it?

In general, if gait, ROM or muscle strength improve--that is a good improvement. Again, each of those can be specific too!

Brett, or others more FMS trained than myself--once you can analyze gait, other than specific movements/patterns you want to test, I find gait to provide the most information (dynamic, autonomous motion) and seems to have the highest transfer (outside of SAID specific work). Is there another benefit to FMS that I am missing? I used FMS in the past, but never attended a formal in person class (just DVDs). I've seen Cook speak on it and other topics a few times and he always has great info.

Not trying to a prick, but just wondering out loud.
Mike N

Brett Jones said...

Answers to your last post "in order"-
Yes to mobility first and yes to it being mainly a semantics issue.

Children have mobility first and then learn to coordinate/stabilize the movements - look at the sequencial developemental sequence.

Yes the individual and most all of us "have forgotten what every 3 year old knows (Gray Cook)" and we lack quality movement due to many factors - sitting, work postures etc...

Ankle dorsiflexion - the individual is in work boots which may simply be impeding his movement - ankle mobility may or may not be the issue (would have to take the boots off and assess ankle movement without the boots) also the FMS is a 7 point test where the ankle issue will become an issue in other tests if it is an issue.
(yes the other person in the photo is in work boots but perhaps more flexible boots)

The Squatter in the photo - if you rotate the photo he should be able to achieve a much deeper and higher quality squat just based on the mobility he displays on the ground - may not be perfect but it is possible for him to do better. But once gravity came into play and he had to "coordinate/stabilize" his movement his squat suffered - this is certainly a neuro issue.

Does the deep squat transfer? Yes - look at the Titleist Performance Institute - they draw strong correlations between lack of quality movement on a modified FMS test and swing mechanics/flaws.
But also the FMS is a 7 point test where you will find asymmetries and "correlating" results - it is not just a squat test.

For every increase in mobility you have to have a corresponding increase in "coordination/stability"

As to your notes from Gray's talk - the answer is yes to both.

Mike N -
Transfer on the toe touch - yes - the "hip hinge" (deadlift) style motion transfers to MANY activities and lacking a toe touch is an indication that that "Pattern" is out - I have fixed it with the FMS corrections but have also fixed toe touches with lateral tilts - whatever works for the individual.

Overhead Squat Transfer - please see the Titleist Performance Institute information and...
Ask the same question in reverse does fixing gait fix the squat?
I have seen people I have worked with who I got a greatly improved gait but still couldn't squat - just because an outside toe pull "activates" glute medius does not mean it will automatically "pattern" into a quality squat.

Gait evaluation vs. FMS testing -
FMS evaluates the three "coordination" patterns - symetrical stance(squat), asymmetrical stance(lunge) and Single leg stance - and divides the body into halves for 5 of tests - Gait is the moving picture and FMS is the snapshots of movement.

This is a good discussion guys - thank you.

Anonymous said...


I have a limited knowledge of the FMS from Gray's book and the 3 DVD's the 2 of you did together. I do this for personal interest and my own training since I don't train people for a living.
What product would you recommend for learning the full 7 screen assessment w/o actually attending a seminar? Advanced Functional Movement Screening and Corrective Exercise Progressions or something else?


Aaron Schwenzfeier said...


Responses in order:

1. semantics agreed upon. I think stability is the wrong word, or may give the wrong impression...

2. Children have mobility first, they are also forced to squat correctly to be able to support their disproportionately large head. Physics and biomechanics at play. If the OH squat guy had the mobility to align his body (which I don't believe he has), he would not need much stability to hold the position, just practice to coordinate it.

3. Ankle dorsiflexion: I guess it could be the boots...???? But what about the difference in knee flexion? And what are your thoughts on the shoulder/thoracic mobility difference between the two subjects. The thoracic/shoulder mobility looks to be a large issue here.

4. Rotating the picture: I did that a while ago and saw TWO guys who would fall, but not because stability, but because the line of gravity falls outside their base of support. Again physics and biomechanics. Mobility allows for this alignment. Hence why a 2 or 3 year old can hit a deep squat position without the strength. The may not hit each rep perfect, but they have the mobility to practice and coordinate/stabilize it over time.

5. Does the deep squat transfer: Maybe, maybe not. Does improving "stability" to fix the squat pattern, transfer? Most definately to the squat pattern, but not necessarily to anything else, because it is a pattern.

Does the toe touch transfer? Maybe to similar patterns like the deadlift.

Gait vs. FMS:
My thoughts, If fix either one, you fix either one.

My main issue is still stating the OH squat guy has a stability issue. At quick glance and without looking through technical glasses, I see a guy who is just "tight". If you spend X amount of time fixing the squat pattern through RNT, do you get carry-over into other patterns? If the guy had the mobility, he could EASILY gain stability in any movement (practice and progressive overload), including the FMS OH squat, any other FMS assessment, or any skill. By just working on the OH squat pattern, the guy gets better at the OH squat, but does he create the "door" to transfer it to anything else? That is the question that I still have.

I think we all can agree that mobility/movement, is key, and anything can be built on top of it.

Does gait change, or FMS improvement, make for a better performance in anything and everything?

Does the FMS transfer to open sport skills at extreme velocities with infinite combinations of movements?

Agreed good discussion, and thanks to everyone's comments. Open for more...

Brett Jones said...

There is a red cover Basic movement screening DVD set that covers a 5 point "self" screen - let me know if you can't find it and I will get the details for you.

Children do have mobility first and then they follow a developmental sequence - picking the head up, rolling, rocking, crawling etc... and then learn to squat from the bottom up not top down - the sequencial development means they develop the "coordination/stability" along with and through the movements.

Yes there are some differences with the "squatters" - but from a passive flexibility standpoint the "poor" squatter is below parallel with the knee angle and has his arm overhead in line with the ears - when he stands up he doesn't - so lets say it is a mobility issue- Why is it a mobility issue? Could it be that the person shows a "lack of coordination/stability" when they try to access their mobility? Thereby locking them up/restricting them?

Again to the issue of transfer - I once again point you to the TPI data and the correlations they have between FMS style movement screening and swing faults - the "snapshots" do transfer.

Gait vs. FMS - I have seen improved gait without improved FMS and ViseVersa.

Yes - FMS corrections and improvements transfer to sport activities/speeds/movements - ask the Patriots, Colts, Giants, Raiders and several other NFL teams and various colleges etc...

Your criticism/question as to the squatter example - what makes you think the FMS corrections do not include mobility work?
And again - it is a 7 point screen - not a one squat test.

As I said earlier - let's say it is a mobility issue - Why is it a mobility issue standing when his passive mobility would indicate he can squat?

Anonymous said...

shut up about the colts as they were one of the most injured teams this last year. No Kool-Aid here.

Aaron Schwenzfeier said...


Thanks again for your response.

You bring up interesting points as to why it is a mobility issue.

In defense of the FMS, I feel the NFL teams are a bad example because of the nature of the game, as both the Patriots and more specifically the 2007 Colts have had some injury problems. Many times injuries in football are unavoidable.

Very interesting of the TPI. Where could I find that information?

Yes, I do know that the FMS corrections focus heavily on mobility. One of the big reasons why movement is getting much more focus in recent years.

I want to be clear, like I said before, I like and use the FMS with the athletes I work with and consistantly use the OH squat as a checkpoint and yes it is a 7 point screen... and my question of transfer could be directed at any assessment, do they truly transfer (principle of specificity)?

One thing that Dr. Mike Stone said in a presentation was about an Olympic weightlifter who went back and changed his technique and worked at his new, improved technique for a couple years. When he competed again, he resorted back to his old technique... technique work didn't transfer to competition...

One more thing; I think the FMS should be a baseline and pass or fail grading for elementary, middle, and high school P.E. classes. Kids are required to pass tests in other classes, why not P.E.?

Again, let me be clear, I like the FMS and I like Z-health.

I would love to take the FMS course. Are you coming to the upper midwest sometime?

But I still think it is a mobility issue! ;) LOL

Brett Jones said...

To anonymous re: the Colts - as Aaron pointed out Football is an "interesting" sport with collisions and contact injuries making interpretation of statistics difficult - but if you look at the list of teams using the FMS they have been doing quite well in recent years.
Any proponent of any system will use "celebrity endorsement" but I guess that isn't allowed here.
In reference to koolaid - well I happen to like the taste - Z koolaid, FMS koolaid, RKC koolaid etc... ;)

Brett Jones said...

You are absolutely correct on the NFL - a collision based sport with 260-300# bodies tends to bring injuries along with it - and there are many other factors. But I guess we can't drink any kool-aide here... is the Titleist Performance Institute website and should have the articles/information you are looking for - if you can't find it let me know.

I'm with ya' on the mobilty work within FMS and transfer of an assessment can depend largely on the adhence to the "corrections" used once the assessment finds issues - Z, FMS etc...all fight this battle. I'm with you there as well.

Transfer to competition and the example given by Dr. Stone - "under stress we revert to training" is a maxim we use in the RKC to emphasize the importance of doing it the way you want to be doing it in the field - I can only assume that the weightlifter in question didn't compete in those 2 years and thus didn't subject his new technique to the emotional stress of competition.
Neural chunking at it's finest - eh?

FMS as a pass/fail in schools - yes I completely agree. Kids are headed in a very sad direction with fitness and movement skill.

I am working on an FMS in the Minneapolis area - check my blog for updates.

The combination of FMS, Z, RKC and other techniques is a good thing and I am certialy with you on liking both systems and look forward to keeping the communication going - I will put a link to your blog on mine.

Yeah - I think it is a mobility issue that stems from a coordination issue (and the boots) ;)

Anonymous said...

read non-contact injuries Brent as the FMS isn't keeping Nomar healthy or making any impact.

The FMS is just a gimmick as any PT with real assessment skills can evaluate an athlete without foolish games.

Brett said...

Posting anonymously is great - Your responses have been rude - getting my name wrong as well...

FMS is not a gimmick or "foolish games" - it also isn't an assessment - it is a movement screen designed to look at fundamental movement patterns to find restrictions and asymmetries.

I was an athletic trainer originally and am very familiar with othopedic assessment and evaluation and I have worked with many PTs over the years and the FMS is my preferred screening tool.

I recommend you attend an FMS workshop and learn a bit about it - or you can just keep posting anonymously.