Core stability and low back pain: How stability exercises might help. Part Two

brain-running-on-treadmill.jpg

In part one of this post I very simple reviewed some of the ideas behind core stability and how I questioned their relevance to a patient's pain presentation.  In this follow up post I will briefly review how people with pain have different function than those without pain and give an opinion on how core 'stability" exercises may help with patients in pain in a manner that has nothing to do with stabilizing the spine.

What do we know and what can we do with patients with low back pain

- some patients with low back pain show delays in Tranny firing

- this delay can be correlated with the presence of low back pain

- changes in muscle timing occur with perturbations to the spine

-improvements in pain and function can occur and have nothing to do with changes in firing onset (see here )

-changes in firing onset can occur and have nothing to do with a motor control retraining plan (see Gary Alison's recent work here which he has been trumpeting this idea for more than a decade, here and here)

- some clinical prediction rules help identify who best responds to a "spine stability program"

- I published two literature reviews years ago that outline how peoples spines function differently with pain (Here and here). The research shows those with pain have differently behaving muscles, changes in proprioception, differences spine kinematics and differences in how they move

But so what if there are changes in function?  Do we need to know this to make improvements in pain?

None of the research suggests that these differences occurred before the pain nor does any research suggest that changing these dysfunctional parameters is necessary for pain resolution.  We probably don't need to specifically address these changes in function with our treatment and most of us aren't.  From the above list there are at least 8 means that the spine is "dysfunctional" as measured with some advanced biomechanical testing.  All of us do not do these testing on our patients yet we are often able to make them feel better.  What does this tell you about advanced testing? It probably isn't necessary.  Or is the test that is most important just the one that your clinic happens to have access to (I'm talking to you you people with Rehabilitative Ultrasound Imaging - I guess you have to justify the cost somehow :) )  We may just need to address the patient's pain, their beliefs, their attitudes, their activity levels and their habits and we will get changes in these functional outcome measures or we won't get changes in those outcome measures and we don't even need to.

These changes in how muscles work can definitely occur in the presence pain.  Where we are confused is correlation and causation. When did these changes begin in relation to onset of pain?  We have some suggestion that changing these motor control variables does not relate to improvements in symptoms (Mannion 2012).  So are these changes just a defense of the body rather than some defect?  They are assumed to be surrogates for stability but are they?

Maybe we should see them as secondary casualties in how our brain works.  The brain changes with pain.  Pain is an output of the brain.  So is motor control.  We can also see changes in swelling, heat, blood flow.  No one thinks that we have to address these secondary adaptations to help with back pain but we think we have to address the motor control or stability issues.  All of which can be secondary byproducts of the persistent pain experience rather than some original criminal mastermind of the patients pain.

 

What do I think my exercise prescription is doing

Breaking habits of motion, changing fear and building self efficacy

Directional preference, flexion intolerant, extension intolerant, activating neurotags etc. Patients have movements that hurt.  Sometimes they continually perform these movements and they keep hurting.  Maybe they were told that they were supposed to sit up straight, brace their spine, suck in their belly and always activate their lazy glutes.  And guess what, sometimes you have these patients relax, move their spine, sometimes slouch, sometimes put their feet up, stop worrying about their glutes and keep active and voila their pain feels better. Instead of "correcting" some stability problem we just gave the patient permission to move with a lot of variety.   We just broke a pain habit.

Sometimes, patients get pain with flexion and for some reason they keep doing activities that flex their spines and they keep having pain.  Sometimes, we suggest that they move the opposite direction, try to find a position of relief and every hour they arch backwards for a few weeks.  Then we slowly have them start flexing their back again (because we don't want them to be afraid of flexion, its what we are meant to do) and now they can flex their spine without pain.  Are these patient's spines any more or less stable? Did their tranny start firing earlier? Who knows, they have less pain.  They began to move differently than what they were previously doing and this helped.  We broke a habit, found positions of relief, built confidence that they could move without pain and transferred that confidence over to other activities.

In some patients you can give them a full spine stability program aimed at buttressing their entire spine. The exercises feel good when doing them.  The patient gets more confident.  They feel stronger and even their pain decreases.  Did their spine's stability become more robust? Maybe.  Is this what caused less pain?  Probably not.  You got this patient moving, maybe you caused exercise induced analgesia.  You put them in control and they felt better.  It probably helped if you didn't tell them there spine was unstable before you gave the exercises.

 

What is my point?

Keep it simple. Adam Meakins (A sport physiotherapists at http://thesportsphysio.wordpress.com/  wrote a simple tweet

 

"In physio you cant go wrong if u do the simple things exceptionally well & save the fancy crap for show offs & bullshitters #ROM #power etc "

This might encapsulate my treatment philosophy in all its foul mouthed glory.  While the body is extremely complex and the pain experience difficult to fully understand our interventions can be quite simple.  We are not car mechanics where we are tightening something or loosening something.  We just provide some input into the body.  The body and brain then decide what to do with it.

I still advise bird dogs, side planks, front planks, curl ups, squats and all the exercises that are in the traditional North American stability paradigm.  Sometimes, I even check to see if you someone can suck in their belly button without other muscles turning on and if doing that decreases the pain in their back when they move their leg.  Do I think that any stability changes occur and this is causing their pain to decrease?  NO. There are other reasons that these movements help.

Do I think that all those planks are creating rigidity in the spine.  Of course not, this is much too simplistic.  So what the hell do I do and what do I think I am doing.

My approach and my rationale

All of the following assumes I have ruled out the nasty stuff.

1. Educate about pain.  Don't catastrophize.  Explain the difference between tissue injury and pain.  Explain that we are meant to move and that pain is normal and is not some indication that they are falling apart.  Explain that their scary x-rays and MRIs are poorly correlated with their pain.   Explain that pain is so much more than just the tissues in their back and reassure them that they can do something about it.

2. Touch them with your hands:  Move them, push, pull, rub, crack, traction, distraction, compression. Whatever.  Manual therapy has some neurophysiological pain modulator effect.  Skip the bullshit explanation about the complexity of the SI joint having an upslip, downslip, a shear or flare or whatever.  You can't feel this and you can't correct it.  But using your hands can modulate the perception of pain and can change muscle and joint performance.  This gets your patients confident that change is possible.

3. Move meaningfully.  What is important to your patients?  Find some movement related goal that is important.  Figure out a way to do this.  Set small goals related to this movement and achieve them.  They might have pain during this task but they know that pain does not mean damage and that they can do it.  Don't hammer them into fighting through pain so that they feel "Wind Up" the next day.  But keeping pushing that pain threshold up.  Keep empowering them.

4. Stress the body.  This is where I use exercise.  I find a movement that is painful.  I figure out someway to modify that movement so that it is not painful (think Mulligan).  Train that movement.  Start to break the habit of pain.  Pain is a habit.  If we activate a pain neurosignature with certain movements we can sometime modify that movement so that that neurosignature is not activated.  Do this.  This is where "spine stability" exercises can come in.  Get them working their achey back in ways that don't cause pain.  This is awesome they train a painful area without experiencing pain.  This decreases the threat associated with movement, decreases kinesiophobia and changes how they think about pain.

5. Train harder: pick a movement that is kind of related to their painful site but does not hurt at all.  Train the hell out of this.  This can be build confidence in their body.  For example, they might have shoulder pain but they can deadlift.  What a great shoulder exercise.  You work your entire body, train the shoulder but experience no nociception.  Hammer this.

6. Address beliefs: we need to understand what our patients think about their condition and how that impacts their psychosocial profile.  If they have some serious catastrophizing, fear avoidance, depression, perceptions of injustice etc this shit needs to be addressed.

An opinion on motor patterns

I have seen "faulty" motor patterns and I have also seen them "corrected" by doing exercises that have nothing to do with retraining the supposedly faulty muscles.  If a motor pattern is corrupted this pattern is most likely corrupted at the level of the brain.  If I train some movement, modulate pain with some education or mobilization we often see changes in these motor patterns.  But I didn't change these as a mechanic.  There was no tweaking at a local level of "muscle imbalances".  We aren't bloody puppeteers The imbalances get "corrected" via other means.  Or they don't get corrected and my patient is pain free and I know that "muscle imbalances" can certainly be normal variations of your complex system.

So just remember this mnemonic: KISDAS.  Keep it simple Dumb AsS.

 

Future posts and questions for research

Corrective Exercise: this approach, besides being an unethical cash grab for CE dollars by some questionable organizations by making good intentioned personal trainers and physios feel insecure, has a number of assumptions about human function that we all need to question.  I also want to investigate it because it is an approach that I kind of use daily (see my defense here of the lowly clamshell) although I try to simplify it and pain neuroscience it up a bit.  And besides, isn't "corrective exercise" what every good coach or therapist does automatically? Find a deficit and improve it?  Anyways,  corrective exercise has a number of interesting things that we can look at and I don't think it is worth completely discounting.  Here are some areas I hope to address:

1. It assumes that there is an ideal way that the body functions.  I think this is everything most physios, trainers and coaches do yet our research is so piss poor.  I would love a catalogue of articles that attempt to categorize the best way to move.  We need to settle this debate once and for all.  The catalogue might just show exceptions and the huge variety that is acceptable.  It might show that their instances when it is best to move on way over another.  I know it is more complicated than just avoiding knee valgus, keeping a neutral spine, not letting 'global movers" shut down "local movers" and assuming that all asymmetry is evil.

2. It assumes that isolated testing (e.g single leg squat, prone leg extension, single leg glut bridge) gives us some insight into altered functioning.  It then assumes that the altered functioning in some isolated test actually correlates with assumed altered functioning during some more meaningful performance task (e.g running, deadlifting, squatting).  I wrote a PhD proposal on this area and you would be surprised how poor our tests are at actually testing anything we think they are testing and also correlating with functional activities. Guess what? Did you know that the quadruped rock back test coupled with spine rotation actually does not "lock out" the lumbar spine and only result in thoracic rotation?  Crazy.  Or that the thoracic spine has just about the same amount of rotation capacity as the lumbar spine.

3. Muscle activation?  Such a neat, simple and prevalent idea.  Training some small movement (e.g squeezing your glutes during a bridge) while "turn on" some muscle during another activity.  I would love to see this idea put through a simple experiment.  Flippantly, it again views the body as something that is so stupid.  Certainly worthy of some good research.

4.   I would love to see a series of blog posts look at altered joint kinematics (what a corrective post assumes it is correcting) and how these alterations correlate with changes in pain or improvements in function. My big hesitation with the corrective exercise approach is that it complicates things and does not seem to recognize the uncertainty that exists in human function. Further, corrective exercise assumes that there is a limited way to "correct" the dysfunction.  aka. you need the "correct" corrective exercises.  I would suggest that there are a multitude of exercises or approaches that can influence pain perceived to becoming from a joint and the resultant aberrant kinematics.  Anyone want to look at this topic?

5. Of course we could also talk about foam rolling.   It is interesting that there does seem to be a shift in the rolling world to get away from the idea of digging out knots and adhesions and focusing on the possible neural aspect for the treatment mechanism.  But fascia is still king in some circles and I can't fathom why.

I would guess that if we look at the biomechanics and motor control literature we would find that our treatments can be much simpler, we would have lots of variety and many approaches would be successful.  We would not have to have incredible complicated solutions to simple problems (avoid the Rube Goldberg trap of exercise prescription).

 

Happy new year!  Anyone interested in collaborating on blog posts please email.

 

Core stability and pain: Is it time to stop using the word stability to explain pain?

sidebridge feet
sidebridge feet

Purpose: To cherry pick a few research articles to suggest that even though our knowledge of core stability is very impressive its link to pain is poor. Nutshell summary: People in pain have spines that function differently than those not in pain.  Many treatments can influence pain.  The spine stability model of low back pain does not explain how people have pain and takes an overly mechanical view of the pain experience.  No test has ever shown that a spine is unstable or how "increasing stability" would lead to a decrease in pain.  Thinking that our spines need more stability or control may be the completely wrong path in explaining how people have pain or how our exercises help them.   Our treatment "corrections" occur not via one specific "corrective" mechanism (e.g. improving stability) but rather through global non-specific mechanisms that our better explained by our understanding of pain neuroscience.  Making the shift from believing that "stability" is the issue with pain can thus free up to choose completely different exercise programs.  Exercise and treatment prescription thus become simpler.  We have preliminary evidence to support this view with the clinical studies that show benefits with the various exercise conditioning programs that train different schools of thought on stability or the just as effective programs that completely ignore any concepts of stability.

Caveat of Ignorance

The purpose of this post is to question things that we say about exercise, low back pain and of course "spine stability".  This is an informed opinion piece and everything I say can be challenged strongly...that's why I write it.  I am also going to put out some "notions" on how I think exercises can help with pain and function.  These are certainly subject to debate and will probably change with time.  I have also ended the piece with a general overview of what I do in Part Two.

A BRIEF and not complete background on spine stability across two hemispheres

Two schools of thought regarding spine stability and low back pain emerged in the 1990s.

The Australians and their inner muscles - Train the local muscles first

The first was based on Bergmark's classification of muscles into "segmental" stabilizers and others into "global" movers.  Segmental stabilizer muscles were often considered to be tonic (constantly on) while the others were phasic (on intermittently to create movement).  This idea of muscles having different roles was suggested decades earlier by Janda.

Low back pain was assumed to occur when the segmental stabilizer muscles were inhibited and the global muscles took over.  The research supporting this idea came from the great work of Paul Hodges (A nice review of Paul Hodges and Motor control can be seen a Todd Hargroves site bettermovement.org).  In early studies, Paul showed that in healthy subjects the transverse abdominis and the multifidus muscle (two local muscles) should fire in a feedforward manner when someone is asked to lift their arm.  Lifting the arm is a perturbation to the body and muscles in the trunk and legs must turn on for us to keep our balance (some call this "stability').  Dr. Hodges showed that the "Tranny" and MFD turn on before or within 50 milliseconds of the deltoid muscle.  Since the muscles become active  before the deltoid we can assume that the brain did some motor planning to prepare the body for the arm raising - muscle activation was NOT a reactive response to the movement of the arm.

With low back pain Dr. Hodges showed that this feedforward (or motor control planning) was delayed in the Tranny and the MFD.  And BINGO a whole  industry was born and the misapplication of science ran hogwild over common sense.  So that's it.  All Paul showed was that in those with pain you got a DELAY in firing.  No one showed that the tranny was weak, no one showed that the muscle was turned off and no one involved in the research said that the Tranny was the most important muscle on the planet.

But somehow physiotherapists, chiros and personal trainers started telling everyone to suck in their stomach when they did squats because the muscle was erroneously deemed to be super important for spine stability.  This was never what the research suggested and caused fits in the North American Spine researchers who really railed against this simple idea.

The other school of thought - Train general core stability (a brief simple version)

birddog1
birddog1

Fortunately, I was innoculated against this because of my MSc with Dr Stu McGill in the late 1990s.  Dr. McGill and Dr. Sylvain Grenier were excellent in challenging the supremacy of the Tranny.  I view their research as less a repudiation of Paul Hodges' ideas and more of an attack of the misuse of Paul Hodges' research.  What McGill and his colleagues had always advocated and also modeled with their biological fidelitous spine model was that spine stability (aka the ability of a system to return to its normal position after a perturbation) was most robust when all of the muscles worked together in the trunk - all muscles were important for stability.  This was again nothing new and we knew this from other joints.  Muscles co-activate, create joint compression and the cost of compression is assumed to be offset by the benefit of stability.   This North American model of stability assumes that all muscles of the trunk work together to balance the stability demands of the spine.  Hence rehabilitation from low back pain should train all the muscles of the trunk in a manner that creates stability but does not do so at a huge compressive cost or adverse tissue loading cost.

Dr. McGill was a leader and pioneer in this.  He was the only one actually evaluating exercises and measuring stability and measuring the compressive/shear loading on the spine to determine which exercises might be "safe".   Dr. McGill was able to classify exercises in to ones which were "safeish" (lower compressive or shear loading on the spine) and others which might have a high compressive penalty but an individual got a good workout (i.e. lots of muscle activity).

The clinical relevance of both the North American and the Australian views are founded on a number of assumptions and unknowns.

What both views assume is that exercise training will make the spine more robust in terms of stability (not more stable, as we know a system is either stable or unstable - you don't make it more stable) and this will lead to less pain and perhaps decrease your injury risk.

Faulty research extrapolations to people in pain and other random stability issues

Below are a number of points regarding the limitations of the relationship between spine stabiliy and pain

1. We do not know why people have low back pain. We do not know what tissue is actually cranky/irritated, fires off a volley of nociception that may ultimately result in the production of pain in the brain (if it even is coming from some cranky/irritated nerve embedded in tissue and is not wholly a production of pain from the brain in response to some perceived threat).  We can not say that a disc is pissed off, a muscle is cranky, a facet joint is upset or if some ligament wants a vacation.  Damage in the spine has a poor correlation to pain. So if you can't identify what tissue is the source of nociception (and we can't) what is the mechanical basis for the prescription of any stability exercise?  How would changing the stability of the spine decrease nociception? If you think spine stability exercises actually change stability parameters by what mechanical means does this change nociception? If you think spine stability exercises help your patients and clients but you can't explain it via a mechanical explanation (but you know it works) do you think there might be  something else going on besides stability issues that you are affecting to influence the perception of pain?

2. Who cares if a muscle is delayed 50 milliseconds?  Really, what relevance does this have.  The muscle turns on eventually and does its job during a task.  Why is a delay of 50 ms relevant in terms of biomechanics.  Is this delay a defense or a defect?  Is the problem in the spine (unlikely) or more a symptom of "something is up" with the brain (more likely, and this is where Dr. Hodges is doing most of his work now yet in popular clinical culture we are stuck at the level of spine). I will go into Hodges work later in another post because I think his work on motor control and the brain may be extremely relevant.  Big point here, Hodges never measured stability.  Just muscle activation in all the muscles that make up the trunk cylinder (side note: he did a wonderful job here, I think his research is excellent, he is an excellent researcher and his contributions to our understanding in the area of motor control are without par.  I would also prognosticate that his future research might bridge the gap from mechanical views of spine and pain neuroscience).  Everyone just jumped on the stability wagon and assumed that it was compromised.  Maybe there is something else going on here besides stability.

3. The argument for the motor control camp against bracing and planking - "Don't brace or do planks because your spine becomes rigid" is a wee bit weak.  This is the argument against the North American model of spine stability and is used to justify"motor control" or low level exercise. It suggests that if you do a bunch of planks you will become rigid and activate your muscles too much. I disagree with this puppetry view of the body. Doing planks will not somehow carry over to rigidity in our activities of daily living.  We aren't puppets where we can tighten and loosen the strings of our spine. This is catastrophizing against a therapy rather by the patient.  These exercises aren't that powerful both in a negative or a positive way.  However, if you actively brace and assume a rigid posture as a choice during all of your normal activities then you can make this argument.  Don't blame the exercise blame the conscious choice of movement.

4. Do you think your patients are really "unstable"? Patients are in pain.  They move differently, you might perceive them to have "tight" muscles.  But is their spine really unstable? Is there a vertebrae in there sloshing around, sliding this way and that, pinching on stuff.  Is the spine really buckling?  We can have patients with high levels of spondylolithesis and their spines are not unstable.  I think we might want to reconsider telling our patients that their backs are unstable and they need stability exercises.  How much fear do you think this creates?  No one has ever shown that a patient with persistent low back pain has funny uncontrolled movements at a segmental level in the spine.

5. But my SI joint needs force closure, I need to train my Tranny or MFD or some bloody fascial sling.

How  is your SI joint unstable?  What wonky movement do you really think is happening in there?   I believe that there is less than 2 degrees of movement and a few millimetres of slide in that SI joint but how is having a delay of 60 milliseconds in one muscle changing this movement?  If it does change that movement why does this cause pain? And so what if the joint slides too much.  Other joints slide around and they don't create nociception.  And if you have a delay in the tranny won't the big, bad global muscles be on at the same time and thus increase force closure and shut down the movement.

These global muscles certainly have the architectural requirements to create force closure.  None of this makes sense. Oh wait, those global muscles are on too much and that causes too much compression in the joint and that causes pain.  Oh, gotcha that makes perfect sense.  But guess what, no consistent research actually suggesting that this happens.   The studies showing increases show increases that are extremely subtle and again how this would cause pain is never laid out in any logical or supported manner.   Well what if that joint is fused?  That seems like a lot of compression.  Should that not be painful yet its not? And why would compression from muscles be painful? Would someone not be better lying down and not lifting weight, walking, running if compression was so nasty for the SI.  More compression on a joint is not necessarily bad and does not lead to pain.  There is something else going on here.

childs pose
childs pose

5. Is it really that bad to get away from the neutral spine? I agree that a neutral spine is generally stronger when the spine is undergoing maximal compressive and shear loading.  Maintaining a neutral spine when deadlifting, doing kettlebell swings, squats and picking up your sofa makes some sense to me.  But do I really need to never bend or twist my spine.  It has a certain amount of movement built into it.  Why would I not use it?  Motion is lotion.  We would never tell another body part to not move.  Taking away movement is how we torture in Guantanomo.  The majority of spine pain does not occur because of we have overloaded it to an extent where it reaches the limits of tissue injury capacity.  This may be one of those issues where we can confuse injury with pain.  Neutral spine bracing can probably help with injury and performance when under high loads but is it necessary to decrease pain in someone getting up from a chair with low back pain?  I will grant that sometimes when you brace and move with a neutral spine and get out of a chair you have less pain.  In other people it gets worse.  Maybe there is something else that explains this besides stability.

6. Patients get better with all types of spine exercise programs.

We have clinical efficacy trials showing that a motor control program (e.g sucking in your belly and then progressing with more global exercises) and a global exercise program helps for low back pain.  So do general exercise programs.   We know that exercise for the spine can help but perhaps it does not matter which exercises we do.  When we get similar results from two different theoretically supported exercise regimes perhaps there is something about the two different programs that is similar.  Perhaps it is that similarity that leads to improvements in pain.  A recent paper by Mannion et al (2012) championed a similar idea.  In other words, we get results but not for the reasons that we think we get results.

7. I think we scare the shit out of people when you tell their spine needs stability

This the default word that many of us tell our clients.  "You're unstable, you can't "control" your movement and that is why you are in pain".  Its so defeatist and catastrophizing and really has little support.  I say we stay away from these words...See my previous post here on this same topic (The words we use can harm)

Recap

You can rehab a patient using the two different schools of thought on spine stability.  You will probably have similar results.  Conversely you could just have patients exercise their entire body and they will also show improvements. You will also have good results if you just teach people about pain and give them the confidence to keep moving and not get worried about their "bloody lack of stability" that some therapist told them they once had.

Stability is probably the most inappropriate word we can use to describe our patient's spines that are in pain.  No one has documented that patients in pain have unstable spines nor is there any reliable clinical test for it...yet we have been using this word for twenty years.  That is crazy yet so many of us think that we have to "increase the stability of the spine" in those with low back pain.  No one has shown how any dysfunctions related to "stability" actually cause pain. Again, crazy.  Yet we tell patients they need stability exercises to correct some mysterious bogeyman.   When we get results with completely different movements or exercises that totally conflict in terms of spine stability theory this tells me that the reason our treatment is effective probably has nothing to do with stability.

In part two, I will layout how the spine function is different in people in pain and also give some theories on what treatment does to help our patients.

Exceptions to the exceptional joint by joint approach

Exceptions to the joint-by-joint approach – by Greg Lehman with commentary from Bret Contreras. by Greg Lehman and Bret Contreras

Quick Background: The joint-by-joint (JBJ) approach, popularized by Mike Boyle and Gray Cook (link here), is a method of categorizing how each joint should ideally function and what tendencies a joint might have toward dysfunction. It also suggests how joints interact with each other and might provide shortcuts to identifying shortcomings in a joint’s or system's functioning in the cause or persistence of pain, injury or less than ideal performance.  The assumption of the theory is best illustrated with this quote from its original description:

Injuries relate closely to proper joint function, or more appropriately, to joint dysfunction. Problems at one joint usually show up as pain in the joint above or below.

Purpose of this critique: On first glance (and still) of the JBJ I thought it was beautiful. So simple, so elegant.  It is a common idea to look both above and below a painful joint to hopefully find the criminal that is creating the painful victim.  So at first blush I loved it, but as I thought more about it, I kept seeing exceptions to the rule.  And if exceptions exist to this theory, then maybe the theory is less useful and does not accurately describe function.

This post is not specifically evaluating whether an assumed dysfunction at one joint leads to injuries at other joints (i.e. questioning regional interdependence), although I think that is important to do.  I am merely pointing out exceptions in the tendencies at each joint and how these exceptions suggest to me that joints may not be governed by these tendencies and are obviously more complicated.  If there are common exceptions at every joint then the JBJ does not accurately reflect reality.

A caveat about critiques:I could not create this observation (the JBJ) about the body – I am not that clever or astute. I have a lot of respect for Gray Cook and Mike Boyle in creating and publishing their ideas.  However, I think that theories are meant to be tested.  The book Movement is attempting to become a university textbook and the ideas within it should be subject to some rigour.   No one would consider it poor taste to critique a theory about the origins of the universe just because you had a lot of respect for the physicist.  In the same light, the JBJ theory should be questioned because it makes bold statements about the ideal functioning of the body.  Further, looking and questioning theory helps me understand it.  All this being said, I think that anything I write here Gray Cook already knows.  After writing this post in rough months ago, I essentially found a “rebuttal” by Gray Cook called expanding on the joint by joint approach here.  He explains the limits and utility of the JBJ well and also provides more food for discussion on how the body should function.  He even comments on exceptions

Of course you will find exceptions, but the more you work in exercise and rehabilitation, the more you will see these common tendencies, patterns and problems.

Bret’s Notes: I agree – I could not have come up with the JBJ approach as I’m not that clever either. I think it’s a brilliant model and is incredibly simple and elegant. I've learned a ton through Gray and Mike over the years but everything should be questioned and scrutinized in the best interest of scientific advancement.

I’m more of a biomechanics and CSCS, so I don’t have experience in physical therapy. But coaches and trainers typically train folks in various states of dysfunction, which gives me some confidence in critiquing the JBJ approach. Based on my limited experience in rehab, I agree with Gray in that the body tends to break down in the manner described below, and in general I’m a supporter of the JBJ, but like most models, it needs additional clarification.

Here is the joint by joint in a nutshell. I list the joint and what is assumed to be needed at that joint

1st MTP: mobility Midfoot: stability ankle: mobility knee: stability hip: mobility lumbar spine: stability thoracic spine: mobility scapulothoracic region: stability glenohumeral joint: mobility lower cervical spine: stability upper cervical spine: mobility

And in Gray Cook’s words this is how he describes it:

A quick summary goes like this—

1. The foot has a tendency toward sloppiness and therefore could benefit from greater amounts of stability and motor control. We can blame poor footwear, weak feet and exercises that neglect the foot, but the point is that the majority of our feet could be more stable.

2. The ankle has a tendency toward stiffness and therefore could benefit from greater amounts of mobility and flexibility. This is particularly evident in the common tendency toward dorsiflexion limitation.

3. The knee has a tendency toward sloppiness and therefore could benefit from greater amounts of stability and motor control. This tendency usually predates knee injuries and degeneration that actually make it become stiff.

4. The hip has a tendency toward stiffness and therefore could benefit from greater amounts of mobility and flexibility. This is particularly evident on range-of-motion testing for extension, medial and lateral rotation.

5. The lumbar and sacral region has a tendency toward sloppiness and therefore could benefit from greater amounts of stability and motor control. This region sits at the crossroads of mechanical stress, and lack of motor control is often replaced with generalized stiffness as a survival strategy.

6. The thoracic region has a tendency toward stiffness and therefore could benefit from greater amounts of mobility and flexibility. The architecture of this region is designed for support, but poor postural habits can promote stiffness.

7. The middle and lower cervical regions have a tendency toward sloppiness and therefore could benefit from greater amounts of stability and motor control.

8. The upper cervical region has a tendency toward stiffness and therefore could benefit from greater amounts of mobility and flexibility.

9. The shoulder scapular region has a tendency toward sloppiness and therefore could benefit from greater amounts of stability and motor control. Scapular substitution represents this problem and is a common theme in shoulder rehabilitation.

10. The shoulder joint has a tendency toward stiffness and therefore could benefit from greater amounts of mobility and flexibility.

It is theorized that if a joint moves away from this idealized function (and demonstrates the faulty “tendencies), one will experience dysfunction up or down the chain. This is termed regional interdependence.  What I question is whether this is a useful or accurate viewpoint on human function considering that every joint has an exception to these tendencies and many of these exceptions are not just minor outliers.  They are quite robust and prevalent.

Bret’s Notes: While I agree with Gray’s summary and am a big proponent of the “regional interdependence” theory, I’m also of the belief that all joints need specific levels of mobility and stability training. I’m with Greg here – there are certainly lots of exceptions to the JBJ, and some of the exceptions are incredibly important, which casts doubt on the simplicity of the JBJ model.

 The Exceptions

1st MTP (mobility assumed to be good)

Having “instability” or too much movement of the 1st metatarsal (e.g. it dorsiflexes) does not allow the the MTP to dorsiflex. Therefore, you need stability at this joint for mobility to occur.  Therefore the assumed deficit is a lack of mobility whereas the actual tendency towards dysfunction is a lack of stability. The perceived dysfunction at this joint is termed functional hallucis limitis and has been questioned by many biomechanists.   See a review here.

Midfoot (stability assumed to be good)

The pronation (or a sloppy midfoot) bogeyman shows poor correlation to injury. Yes, the foot must supinate (e.g. create stability) to lock out the midfoot for power production but we can’t assume that having a lot of pronation means that we lose force production and are at risk for injury up the chain. This has not been proven as a consistent risk factor for injuries yet it persists despite many reviews questioning its significance.

The video below shows a former world recorder holder in the marathon and 10k demonstrating huge amounts of pronation. It is hard to argue that he is leaking energy or that this pronation leads to some other damage up his kinetic chain.  This runner is 38, still running and still competing.

http://youtu.be/EAW87NsiGuI

Ankle (needs mobility, tendency towards restriction):

An exception would be the tight calf muscles demonstrated in runners with a corresponding increased mechanical efficiency (a recent cherry picked paper here and here).  There is also a lack of research linking tightness in dorsiflexion with prospective injuries.

Further, I am not arguing that increasing flexibility will negatively influence the performance in runners.  I have heard this argued and think the jury is still out.  Here are a few abstracts showing no change in running economy following acute and chronic stretching regimes (herehere and here).  Note, I did cherry pick here.  There is some research suggesting acute stretching does influence running performance, point is, it is still up for debate.

Final point: athletes can get by without restricted dorsiflexion in many sports.  Do we always want to go changing this?  Can you with certainty conclude that a lack of dorsiflexion is a true dysfunction? I think a massive post on restricted dorsiflexion and injury, form and performance would be cool.  Any takers?

Bret’s Notes: Greg raises some excellent points. I’m of the belief that lack of dorsiflexion is certainly dangerous in weight training as it can lead to form decrements such as lumbar flexion during heavy squatting. However, it’s probably not as dangerous for sports performance where you don’t have heavy weight on the back. Furthermore, there’s probably a big difference between the biomechanics of “stiff joints” in weaker, sedentary individuals versus athletes. For example, joint stiffness adaptations in athletes may be caused by a shifting of the optimal length and/or alterations in sarcomeres, titin stiffness, or connective tissue stiffness. However, in a perfect world, most coaches would agree that they want their athletes to possess sufficient ankle dorsiflexion ROM, so I tend to focus on what’s “optimal,” rather than what’s “acceptable.” Therefore I agree, with Gray and Mike; most people would benefit more from mobility-related training than from stability-related training for the ankle joint.

Knee (stability is assumed to be needed)

Of course we need stability but do we actually see unstable knees except when a ligament is blown out? While laxity of ligaments (abstract here)may predispose to injury we can't see this with the naked eye.  Depending on how you define stability, are you sure that it is the knee that is “unstable” when you see the knee looking sloppy?  The knee just follows the path set by the hip.  There isn’t an instability that can be seen or measured until you damage some internal restraint.  We don’t train the knee for stability we train the hips in association with the knees.  The knees benefit from the control of the gmax, gmed, gmin and hip rotators and on an unseen level the hamstrings.

http://youtu.be/wbvf37vmfoQ

An exception to the JBJ rule is the type of mobility we need in our knees (i.e. the tendency for the knees to lose mobility). We need full extension.  A loss of this following injury or surgery is huge for dysfunction.  Check this link here. Further, we need the joint surfaces to translate and rotate – that is why some therapists do Mulligan techniques, manipulations or mobilizations.

Bottom Line: The knees are stable because of what we do at the hips or the passive restraint system of the ligaments (untrainable).  Mobility of the knee is also important. Because of these exceptions I don’t see there being a tendency to sloppiness at the knee because that sloppiness (if relevant) is from the hip and therefore I question the JBJ.

Bret’s Notes: For the past few years, I’ve been heavily influenced by researcher Chris Powers, who feels that knee issues are almost always due to problems at the hips. However, a conversation with a high-level biomechanist in Auckland in addition to a couple of recent journal articles led me to believe that optimally-functioning knees are not just about the hips – we need strong quads to influence pressure distribution, strong hamstrings as co-contractors for stability, and I’m still open for VMO potential, but more research is needed in this area. So knee health is highly dependent on hip mechanics, but I feel the knee can be trained for improved stability and improved biomechanics, meaning that the inherent forces and stress distributions (patellofemoral joint contact area is increased via quadriceps strengthening, the ACL joint is spared from hamstring co-contraction, etc.) can be reduced through strengthening muscles acting on the knee joint. So I agree with Greg about the importance of hip stability but with Gray and Mike about the importance of knee stability.

Greg's response to Bret: I am not arguing that knee muscles are involved in stability and health of the knee.  What I want to emphasize is that the sloppiness we see at the knee joint is more than likely due to alterations in how the hip or spine controls the position of the knee or even the soleus. Poor mechanics of the knee are primarily controlled by something else other than the muscles that just cross the knee.

Hip (assumed need – mobility). 

The rationale here is that if you don’t move in your hips you will move your lumbar spine and predispose yourself to injury. I love this idea and am reading a great PhD thesis by Janice Moreside (a student of Stu McGills) on this idea exactly.

The obvious exception to the lack of mobility tendency would be the many biomechanists who argue that knee injuries are related to alterations in control of the femur (increased hip internal rotation and adduction). You can certainly make a strong case for hip “stability” being required to prevent injuries and certainly being a greater risk factor for dysfunction. Because of research funding and the difficulty of research, hip extensibility has less research supporting its relationship with injury. Regardless, these competing biomechanical rationales suggest that the JBJ theory has problems.

However, it should be noted that the authors of the JBJ already recognized this exception and wrote:

The exception to the rule seems to be at the hip. The hip can be both immobile and unstable, resulting in knee pain from the instability–a weak hip will allow internal rotation and adduction of the femur–or back pain from the immobility.

However, we can also question whether losses in sagittal plane range of motion does lead to increased strain, changes in movement at the lumbar spine and subsequent injury in the spine.  I’ve questioned this before here. One example is the research that looks at individuals who have a loss of hip extension on a Thomas test don’t actually create more motion in the lumbar spines during running.  Yes, this is one study and more needs to be done.  I am just saying that this is again something worthy of discussing.  Last, in Dr. Moreside’s PhD thesis, increases in hip extension following training were not associated with decreases in the amount of spine extension that occur with an active hip extension movement (I am following this up with a post summarizing Dr. Moreside’s great hip and spine research if you are interested in reading more of this).

Hip Bottom Line: The Hips need both stability (motor control training, movement, strength, endurance) and mobility.

Bret’s Notes: I am in complete agreement with Greg here. I don’t know what’s more “important” for injury-prevention purposes – hip mobility or hip stability, but suffice to say they’re both incredibly important. Hip instability begets knee pain. For more info on this topic I highly recommend reading THIS paper (click on the link and download the pdf). There exists research indicating that hip instability contributes to low back pain and anterior hip pain as well.

I believe that the exception at the hip provides the second biggest blow to the JBJ approach. In theory, it would be lovely to see this beautiful, alternating pattern of joints needing mobility and joints needing stability. While it’s a nice overall model, the exceptions must be noted. This brings me to my next point – the biggest single blow to the JBJ approach:

 The Pelvis!

The pelvis joint is completely ignored in the JBJ model. The pelvis needs mobility, but even more important is pelvic stability. I am of the belief that pelvic instability is a huge criminal in terms of creating mechanical insults to the spine. I’m not sure if Gray and Mike purposely left out the pelvis in attempts to simplify the model and allow for the “alternating” approach, or if they simply overlooked it, but I feel it’s time we started giving the pelvis much more attention.

Many individuals are unable to adequately tilt their pelvis in various directions, and they lack the ability to dissociate the spine and the pelvis. If the joint doesn’t function properly dynamically then I doubt it functions properly statically. Individuals typically possess incredibly poor motor control in this region and could benefit greatly from static and dynamic strength training for the pelvis. Core stability doesn’t just involve the lumbar spine and hips; the pelvis is just as important. Furthermore, research has shown that muscle function is unique depending whether core muscles are acting on the spine/ribcage or the pelvis.

I believe that this is a major area for future research and improvements in human movement mechanics and I have personally achieved success with my clients in implementing pelvic neuromuscular training strategies.

Lumbar spine (assumed to need stability and have a tendency to being sloppy):

I won’t even get into this. Too big, too messy, too contentious.

I would just ask “do you think it is all that bad to bend your lumbar spine during simple unloaded activities”?  Can you name 5 sports that see huge ranges of spine motion as being necessary for success in that sport?  Do some athletes even use a flexed spine to lift heavy weights (although they can still be stable, a great study by Stu McGill is here.  Lots of lumbar flexion during lifting but that position was buttressed with stability derived via cocontraction).

Take a look at the range of motion in the spine in the graph below.

Do you think it is only occurring in the thoracic spine?  Please note, the pictures are not exactly linked with the ROM curves.

Bottom line: the lumbar spine probably needs some mobility and stability.

Bret’s Notes: The lumbar spine indeed loses considerable motility as we age, and while I agree that stability is more important than mobility in this region (research shows that increased spinal flexibility doesn’t reduce back pain, but again, I focus on what’s “ideal,” not what’s “acceptable”), I don’t feel that it’s ideal to accept mobility losses. Smart training can allow people to keep their 3D lumbar spine mobility (or even build lumbar spine mobility) while not posing too much of a threat for injury, as long as end-ranges of spinal motion are avoided. That said, even when we think we’re stabilizing the core, the spine is moving. This has been shown with squats, deadlifts, sprinting, and even kettlebell swings.

Over time, with proper training, the brain probably figures out the best compromise between performance and spinal health and determines just how much ROM to allow in each segment and how much muscle activation is required in the various core muscles to “tune the stiffness” and stabilize in non-neutral positions.

Greg's outrageous comment to Bret: This might come as a surprise but of the studies done to date there isn't consistent support that spine stability exercises are markedly more effective than other exercises (motor control exercise, graded exposure, general exercise) for the treatment of back pain.  Pain is a separate beast and we have to be cautious in thinking that just  hammering stability will decrease pain.  Prevention of injury may be something different.

Thoracic spine (needs mobility): I don’t have a strong exception that I absolutely stand behind. I just think that like any joint it needs to both move and be challenged with physical stress (stability).  There are researchers that suggest the thoracic spine is also subject to the same form and force closure demands that the SI joint exhibits.  I believe they might argue that “instability” or a tendency to sloppiness can also occur here if you look for it (see Diane Lee and LJ Lee in their Thorax book www.discoveryphysio.com).  Just another exception to consider.

 Bret’s Notes: Sure the ribcage adds considerably to the t-spine’s stability, so this portion of the spine has a built-in stabilizer. However, some research shows that the thoracic intervertebral discs suffer from an alarming number of herniations just as the lumbar discs do. Of course, this isn’t well-correlated with pain, but I’m sure that most individuals “break down” in terms of erector spinae weakening and can benefit biomechanically from increased static thoracic extension strength, especially in weight-training.

When under load, you can have all the mobility needed but without strength the upper back could round too far forward and cause problems over time. Furthermore, I feel that poor postural habits in addition to weak muscles contribute to the stiffening of the t-spine as muscle force is required to pull the t-spine into proper position in the first place.

Scapula (needs stability): this one is easy using biomechanical reasoning. We need the scapula to get out of the way of the arm bone. There is cross sectional evidence suggesting that those with impingement type pain have less posterior rotation and elevation of the scapula. This joint has to move…it must posteriorly tilt and upwardly rotate.  I suppose you could flip things on their heads and say that a lack of mobility in one direction is really a lack of stability in the opposite direction.  The motor control deficit here is that we don’t control the scap to get out of the way.  Again, I recognize that stability can be compromised when we don’t want the scap to move but the point of the article is to show that every joint has an exception and that all capacities are important.

Glenohumeral (needs mobility): Well of course it needs mobility, can’t argue that, but biomechanically we also argue that the head of the humerus needs to be positioned properly in the socket…this is stability. Deviations from this (anterior or superior glide) are biomechanically considered to be linked with pain.  Again, mobility and stability are both important.

Summary

The tendencies at some joints can certainly occur and they might even be linked with pain and dysfunction (although, I think this can be debated in another post and was only briefly touched on here, e.g. pronation), but the point of this blogpost was to highlight how often we have exceptions to the JBJ. So we have observed tendencies but also common exceptions at the same joint.  When we have this many exceptions to the JBJ rule we might want to consider questioning whether this is a theory that adequately describes human function.  Is it even helpful if there are so many exceptions?  What I would stress here is that Gray Cook probably already knows this stuff and would be flexible in his programming and assessments about function anyway. I bet he doesn’t even need the JBJ and nor do you. But, lots of other people may not view the JBJ with such flexibility and can become dogmatic and rigid.  This post was for those individuals.

Bret’s Notes: I’m sure that Gray and Mike are well-aware that each joint needs both mobility and stability, but the JBJ model is directed at dysfunction and portrays how the effects of gravity, poor posture, and sedentarism typically affect joint behavior. I still like the JBJ and teach it to my students, but I also point out the exceptions and stress to them that all joints need varying degrees of mobility and stability, and I especially stress the contentions at the hips and pelvis. The model created by Gray and Mike is both genius and useful, but it needs further explanation to be more complete.

Gray’s main point in this quote hits the nail on the head: “The whole purpose of the joint-by-joint concept is to realize generalities…The examples are there to make you think above and below the area you’re working on and in the things you’re asking for.”

So the way I see it, the JBJ model could be improved dramatically just by adding in the following two adjustments:

1st MTP: mobility

Midfoot: stability

ankle: mobility

knee: stability

hip: mobility and stability

pelvis: mobility and stability

lumbar spine: stability

thoracic spine: mobility

scapulothoracic region: stability

glenohumeral joint: mobility

lower cervical spine: stability

upper cervical spine: mobility

Greg's Last Points

The exceptions pointed out above illustrate to me that most joints need both mobility and stability and we can make an argument to train capacity in all realms of joint function to maximize a happy body.  I would even go so far to suggest that some tendencies to dysfunction suggested in the JBJ (and by Bret) are not even dysfunctions...just the normal variability that the body possesses.  I disagree somewhat with Bret with the tendencies he suggested above.  That is cool.  My opinions are provisional and will certainly change with more information.  Its interesting that you can't look at the same research and have different final opinions.

Last, I won’t even discuss pain.  The link between assumed “altered biomechanics”, “poor form” and future injury and pain is extremely weak and may even be non-existent.  This is something again worth discussing, just not here.

Postural correction and changing posture. Can we treat our patients like puppets?

Audience: Therapists and Strength CoachesPurpose: To justify the use of a variety of exercises (even general exercises) for training, rehabilitation and injury prevention and question the application of movement specificity principles.

The Gist of this Post: Specificity of training is an important component of rehabilitation and strength and conditioning but I think the application of specificity can be taken too far when we attempt to mold our posture.

A related post by Tony Ingram touches on many of these ideas in relation to pain and posture.

Background

The godfather of specificity was a former professor of mine, Digby Sale.  For a brief review see here.  Very briefly the research suggests:

"Evidence supports exercise-type specificity; the greatest training effects occur when the same exercise type is used for both testing and training. Range-of-motion (ROM) specificity is supported; strength improvements are greatest at the exercised joint angles, with enough carryover to strengthen ROMs precluded from direct training due to injury. Velocity specificity is supported; strength gains are consistently greatest at the training velocity, with some carryover. Some studies have produced a training effect only for velocities at and below the training velocity while others have produced effects around the training velocity"

Another great review article is by Cronin et al (2002) link here:  A quick quote from the abstract:

"It has been suggested that training at a specific velocity improves strength mainly at that velocity and as velocity deviates from the trained velocity, the less effective training will be. However, the research describing velocity-specific adaptation and the transference of these adaptations to other movement velocities is by no means clear".

My thesis: The applications of specificity can be taken too far in three ways

1. The repeated performance of an exercise leads to plastic deformation of tissues or changes in motor control that cause significant changes in posture and movement capabilities (aka form).

I question if the body is really this malleable and ahem, stupid.  It assumes that consistently training certain movements makes you move in that specific way and you lose the ability to move in other ways (i.e. your posture and form become changed).   I believe it is an inappropriate extension of you become what you train.  It is a training belief related to the idea that hip flexors become shortened because we sit all day (see a previous post here).  I don't doubt that you can train habits of movement that might carryover into other tasks.  What I question is whether are tissues are so readily plastic and they can't control their destiny because of some passive changes in the make up of the tissue. 

An example...

I was listening to a podcast where the speakers objected to what they felt was the rampant, unjustified, often silly and apparently detrimental usage of the front and side plank (bridge) by physiotherapists and trainers the world over.   What the speakers argued was that performing these repetitive planks with no motion between the hips and the thorax would somehow create runners that will run like robots and lose the ability to dissociate the hips from the thorax.  As if twenty minutes of planking a week will somehow carryover to the automatic movements that occur during running.

I just don't buy this and consider it such a pessimistic and wholly unfounded structural view of the body.  It assumes that the body is stupid and a few minutes of planking will somehow override what ever neural control mechanisms, not to mention physical forces, that create subtle movement in the spine when we run. 

A brief review of 3D spine kinematics during running can be found here (Schache et al 2002 ) and here (Saunders et al 2005).

We don't change form through simple exercises...or do we?

The belief that planking makes you rigid and run like a robot has not been tested but assumes that planking will somehow stiffen up all the muscles of the trunk within the neutral zone and also cause our brain to change the automatic way in which it recruits muscles during locomotion.  That is some powerful planking to override our nervous system like that.  It is very difficult to change running kinematics even when we try to change running kinematics by volitionally changing our posture.  But somehow, a little bit of planking can do this despite us trying to run normally. 

Same holds true for the knock on the curl ups.  I think it is a fair to critique curl ups  for other reasons (e.g. there are better exercises, you may not think they are functional, you don't like the idea of compressing a disc with some flexion) but I don't think we can turn people into kyphotic zombies.  Unless you've been bit by a Kyphotic zombie and those are biochemical changes not biomechanical. Curl ups get critiqued because it is assumed that doing a lot of curl ups will end of shortening the rectus abdominis and will therefore be constantly flexed.  I just don't see any research suggesting that this happens.  While we might increase the stiffness of the rectus abdominis this is different than making that muscle shorter at its resting length.  The muscle has a stress strain curve where there is hardly any resistance to movement around its resting length (i.e. the neutral zone) while strength training might shift that curve if stiffness increases it still has a "toe region" of the neutral zone where hardly any passive force is created.  Certainly not enough to crank down the thoracic spine and all of the other opposing muscle groups

Some Research on changing posture and form through exercise

Here is a sampling of studies looking at both strengthening and stretching programs designed to change Scapular position or posture in general .  This is ridiculously difficult to do.  None of the following studies were able to do it:

- a review here by Con Hrysomallis looking at Shoulder position  http://www.ncbi.nlm.nih.gov/pubmed/20072041

- a review by Hrysomallis looking in general at the ability to change posture: http://www.ncbi.nlm.nih.gov/pubmed/11710670

-Wang et al (1999) Stretching and strengthening exercises: their effect on three-dimensional scapular kinematics.: http://www.ncbi.nlm.nih.gov/pubmed/10453769

- McClure et al (2004) Shoulder function and 3-dimensional kinematics in people with shoulder impingement syndrome before and after a 6-week exercise program: http://www.ncbi.nlm.nih.gov/pubmed/15330696

-Hibbard et al (2012) Effect of a 6-Week Strengthening Program on Shoulder and Scapular Stabilizer Strength and Scapular Kinematics in Division I Collegiate Swimmers: http://www.ncbi.nlm.nih.gov/pubmed/22387875

Serendipity of the internets

I have been writing and thinking about this post for months and along comes a post from Bret Contreras arguing that strength training alone does not change form. He argues that motor control training changes form.  This is a component of what I am trying to say.  Here is a link to Bret's piece

MY ARGUMENT DOES HAVE SOME RESEARCH AGAINST IT...Sort of

BUT...to weaken my arguement (and engender some healthy doubt or hope :) ) there are some papers that do show a change in posture albeit inconsistent. 

 1. Here is a great paper by Scannell and McGill(2003) - Stu does all the great stuff!

But, there was not a change in the stiffness of the spine nor did this lordotic static change carryover to a functional task

There were no changes in the size and location of the NZ of each group recorded during the mid-training and posttraining tests.

Relative to the pretraining test, all 3 groups sat in more lumbar flexion during the mid-training test (P=.005) (lumbar flexion increased by 4° in subjects with hypolordosis, by 5° in subjects with hyperlordosis, and by 5° in control subjects) and the posttraining test (P>.5) (flexion increased by only 1° more in all 3 groups relative to the mid-training test results). The changes in the sitting position between the pretraining and mid-training tests were seen in all 3 groups and therefore cannot be considered a treatment effect

Above Figure Description: The changes in the neutral zone (depicted by the black bars) and the lumbar position during sitting, standing, and walking (50% level of the amplitude probability distribution function) across the pretraining test (1), mid-training test (2), and posttraining test (3) are shown. The subjects with hyperlordosis stood in less lumbar extension during the mid-training and posttraining tests. Subjects in all 3 groups sat in more lumbar flexion during the mid-training test. No changes in the lumbar spine position during walking were found during the mid-training and posttraining tests. Positive values greater than the neutral zone represent extension.

An interpretation of the Scannell Paper

The Scanell paper certainly shows a change in resting posture (e.g. lordosis) but we see no change in lordosis during functional activities nor is their change in the stiffness of the spine.  This suggests that we aren't changing passive properties of the spinal tissues with these exercises but we are doing something else to change resting posture.  Did the participants change habits while doing the exercises and became more comfortable standing in a more neutral posture?  Was their standing posture a choice?

What I take from the conflicting research is that if there is a change in form with basic exercise it is not robust nor is it consistent.  And there is not sufficient information or even biological plausibility to assume that doing the plank daily for 3-5 minutes will somehow result in all of us moving like robots during an activity like running which appears governed by more central patterns.  I can't even imagine trying to run with a non-moving spine.  

A few more papers showing changes in posture with exercise:

2.  Misconception #2: Exercises must be specific in terms of every variable to be considered "specific"

This happened to me when I was trying to publish a paper on strength and conditioning for golf and I had the pickiest reviewer who kept saying that none of the exercises I was advocating as being specific to golf (e.g cable chops, one arm cable punches/pulls, weighted swings, med ball rotational tosses, Swing fan swinging) were specific to the golf swing as they all either had slightly different mechanics or different speeds.  I believe that I asked if a weighted sled exercise was specific to running and I was told that no it was not. I just think it is realistic to assume that a definition of specificity recognizes that some differences in terms of velocity or kinematics is acceptable and that we will still get benefits in the task we want to improve.  The early papers mentioned by Behm and Sale and by Cronin et al certainly support this.

3. Misconception #3: Non-specific or general strength exercises can't carry over to performance/injury reduction for specific tasks.

This is essentially the opposite of number two.  It is a pretty big debate and would rear its head with those arguing for functional exercises versus non specific exercises.  You could also ask "Are specific or functional tasks always better than general exercise?".  MOst of the time people assume (myself included) that specific tasks are better but I think we would ignoring a lot of research that suggests otherwise.

 A specific example can be seen in respect to doing a plank exercise for a runner.  Obviously, no runner gets into this position.  It is not specific in terms of body position with respect to gravity, the movements of running and certainly not velocity.   So the knock against this exercise is that it is not specific to running and therefore can't help the runner.  And I say, who cares? Why does it have to be specific to running? Can't an exercise give us benefits that carryover to other tasks?  Of course they can.  The plank obviously trains the trunk muscles and the lateral hip muscles.  We know that many runners with pain have weak abductors (whether this is a cause or correlation is hotly contested) and at the same time we have some evidence to suggest that training the hip musculature (with exercises that are nothing like the running movement) can be effective in returning people to running and decreasing pain in those with knee injuries. 

What is the mechanism for non-specific exercise benefits

Interestingly, the reason why these exercises are effective often has nothing to do with the purported biomechanical rationale for training the hip musculature in runners.  Specifically, we can advocate training the hip musculature under the assumption that this might change hip valgus and femoral internal rotation during the stride as there is some evidence to suggest that these mechanics are occasionally linked with knee dysfunction.  However, when we implement these hip exercise programs (again with exercises that are basic and totally not specific to running) we will see decreases in pain and return to running WITHOUT changes in the assumed dysfunctional mechanics (check out these papers here, here, here,  here  and here). Of course there are some studies showing that form does change (here and here - albeit no change in kinematics, just moment)  To me, this suggests that there is something generally beneficial about these exercises and that specificity does not have to occur.  But, if you want to change running form than the intervention should probably specifically try to change running form through feedback and training. (see here, here and here)

In terms of performance, I am biased, I do like creating exercises or stealing them that are somehow specific to the task at hand.  However, I recognize that there is a great deal of research that shows that exercises that are not specific to the sporting task can still improve performance (e.g. squats for sprinters).  Again, arguing that specificity is not always necessary.   My main point is the body craves variety and our programming and rehabilitation should reflect this desire.  We don't  have to be so rigid in our prescriptions or believe that there is only one way to get benefits.  The body adapts, lets exult in this.

Future Posts Related to this Topic

This post is a bit of a jumble with a lot different ideas.  I have few posts written half-assed in my head that are related. If anyone wants to write any of the following with me please let me know.  Or stay tuned for these upcoming posts.

These posts will ideally be a gathering of information that generates questions.

1. A catalogue of exceptions to the Joint-by-Joint Approach.

This post will use the framework of the joint by joint theory to consider the research that looks at injury risk factors.  It is not so much a critique of the approach but more a means to understand it limits and explore how it can still be useful.

2. A catalogue of examples that support the Joint-by-Joint Approach

3. Is there an optimal way to move? A catalogue of theories and evidence for ideal movement 

4. Can form be changed with via mechanical changes in tissue?

5. Changing running form through feedback and training.