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

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Published on: December 26, 2020

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)

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.

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)


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.


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15 Comments - Leave a comment
  1. Love it Greg! I’ve had many of these same thoughts in the past year or two.

  2. Great post Greg. And thanks for the link! I have a lot of the same questions and concerns as you that I have been trying to answer in advance of my part two on the Hodges conference. I am also thinking about McGill’s approach and how it compares. I asked Hodges at the conference - if the pain is causing the problem with the motor control and not the other way around, then why bother to correct it? Part of his answer and I think he has stated this in papers as well, is that the altered motor control caused by pain actually does impair function and increase wear and tear. So correcting poor motor control improved functions and avoids long term damage, even if it isn’t a magic bullet for pain. I think he has some evidence in favor of these opinions. I need to check.

    As far as McGill goes, it seems his strategy is to pick exercises that will improve core endurance at the lowest “price”, meaning exercises with the highest EMGF activation levels compared to compression levels. My question is this - if Hodges is correct that poor motor control is about bad timing, and proper division of labor, as opposed to endurance, then why would McGill
    ‘s big three be expected to alter these variables? Any thoughts?

    • Greg Lehman says:

      Thanks Todd,

      Always happy to hear your input. I will be sure to link to your new post as soon as it is done. I asked Paul the same questions (I took his two day course a few years ago) and he said something similar. The whole “wear and tear” thing is where things break down for me. How can you have wear and tear with very low load and not even highly repetitive movements. If it was wear and tear then why we would we not adapt? The “long term damage” is what I don’t get. I don’t see how any damage can even occur.

      I think Gary Alison answers your last question best. To greatly simply Gary might argue that the delay in timing is actually normal variability. Stu might say the same thing. I remember a paper I published years ago where I could not find feedforward activation (measured superficially in at the IO/tranny overlap zone) in painfree subjects. I spoke with Stu and Gary and if memory serves me correct they both suggested this was normal. I don’t know if Stu would expect the tranny timing to change with his big three. I would guess that he might think that it is not important. Paul (with Tsao or Tsai?) has published a study showing no change in timing with Stu’s exercises so there is some data there. Last, I think Hodges was involved with some research showing that spine manipulation may alter muscle timing in Tranny. If manipulation can do this than it suggests that motor control training is not the only means of changing this variable, thus how important is motor control training? Is there some other mechanism to change feedforward and is changing feedforward even that important? Related, there is a researcher named Jansen who did his thesis on adductor strains and showed alterations in Tranny feedforward with the presence of groin pain but then of course when the pain resolved with good training this was not correlated with changes in tranny onset. What does this tell us?

      Way to go Todd, you just got me asking more questions.


  3. Bela Borfoei says:

    The lightness of being.

    The person in pain doesn’t need a more stable spine. What she needs is more awareness of the spine in her nervous system. This awareness is predominately unconscious. It is also more a movie than a static picture. This motion picture can be enhanced through the Feldenkrais Method.
    The solution is at hand, just try it!

  4. Drew says:

    Great article, but you forgot a third model for spine ‘stability’ (motor control is a better term), Pavel Kolar and the Prague school of rehab. Ontogenesis is paramount in understanding spinal motor control.

    • Greg Lehman says:

      Thanks Drew. I would throw them under the same bus too :)


      • Drew says:

        haha, and why would you throw them under a ‘bus’?
        Pain really is an after thought to function. I agree clinicians often ‘scare’ clients into treatment plans using the ’cause and effect’ of there pain source. I’m curious to know why you feel ‘joint centration (DNS)’ or ‘joint by joint’ approach is invalid considering we all develop similarly as infants.

        • Greg Lehman says:

          Hi Drew,

          I think joint centration sounds interesting. It may or may not be related to pain. I think the joint by joint concept is too simplistic. There is not an alternating pattern of mobility to stability needs at each joint. Every joint needs both and I think that these trends are found because people look for them rather than they being obvious. While we all certainly develop from infancy I would not base ideal function on this development. We have different anthropometrics as infants/toddlers, a developing nervous system, different connective tissue properties and a huge range of variability in what is normal. My 2 1/2 year old has trouble rolling over to the right yet she can run and jump. The DNS group have ideas but I don’t think that they have data yet. They assume that they know what ideal human function is. I don’t know anything with such certainty.

          Last, they might get results with their treatment and this might lead them to conclude that it supports their previous ideas of how the body should function. However, their results could be explained via other mechanisms and they just perceive a confirmation of their ideas that may not be warranted.

          These are my observations from discussing DNS with people. I would be interested in learning more about it and perhaps my views might change.

  5. Tony Ingram says:

    Excellent stuff. This: “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.” - that’s the whole point that people are missing. So many more options to help people with pain, such greater flexibility in our exercise prescriptions so that we can truly individualize a treatment plan.

    • Greg Lehman says:

      I’m withya. I think part of it is that we want to look like we are doing something special that differentiates us from other practitioners. Its the overcoaching of simple exercise syndrome. If you train a client you have to always touch and correct their movement as if any deviation from some assumed ideal is faulty.

  6. Thesocialphysio says:

    I appreciate the effort that has gone into the article. I may be living under a rock, but I don’t come across many physios encouraging core fitness on the grounds of “improving poor stability”. Keeping it very simple… If I have a patient who experiences pain on trunk flexion, then I encourage them to see if there are any improvements in that movement pattern with recruitment of TA and internal obliques. If it is, then I pursue the concept of improving general functional strength. I am not sure if it is urban myth …. But I read somewhere once that 80% of back pain improves by simply getting someone fitter ( easier said than done ). Exercise selection then becomes the key ; there are no recipes. We are all individuals with grossly different bio mechanical, psychological and height/weight profiles. I love the ” motion is lotion ” catch phrase. Can I use that? Often the trunk hip dis-association is crucial to encouraging more efficient movement patterns which have ‘shut down’ in response to the pain. Final point, I thankfully have never experienced back pain, however when I did some real time ultrasound experiments on my own TA, I was horrified to find that it was highly delayed in activation and completely contingent on my breathing….took me a long time and a lot of attention to separate the breath from the core.
    Too few acknowledge the importance of breath in low back pain. Thanks again for generating some discussion.

    • Greg Lehman says:

      Thanks. Why were you horrified? It sounds like you had a delay in the tranny (not sure RUSI can measure timing though) and yet you had no pain. That kind of proves my whole point. As of your treatment it all sounds reasonable to me I am just not sure that the pain improvement is because they got fitter or because you just slowly increased their exposure to increasing load over time. The fitness improvement could just be a byproduct and had nothing to do with the pain resolution.


  7. Ronald Kan says:

    Hi Greg,
    I fully agree on all the points you made. After the ‘dynasty of the disc’ in the 30s we now entered the era of ‘the tyranny of the trannie’.
    Looking forward to your next post.

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