Back Pain Myths: Posture, Core Strength, Bulging Discs

Spine and Disc
Problem?

It is an article of faith among many mainstream experts that poor posture, lack of core strength, and/or structural abnormalities such as bulging discs are major causes of pain, especially back pain.  A further assumption is that by working to correct such imbalances, through stretching or strengthening regimes, or surgery, the imbalances can be corrected and pain will decrease.  It is probably fair to say that the majority of physical therapy and corrective exercise that is done in this country is based on exactly these assumptions.  Although these ideas have a common sense appeal, there is significant evidence questioning this approach.  Here’s a brief review of the conflicting evidence.*

Posture

The idea that bad posture causes pain, especially back pain, is ubiquitous.  A google search for posture and pain shows 4 million hits and reveals many sites devoted exclusively to improving posture.  With so many posture police on patrol, you will almost certainly be advised sooner or later that your posture is causing you pain or will cause pain in the future if you don’t fix it.  If you go to a physical therapist with low back pain and a big curve in your low back, you will almost certainly be told that you need to suck in your gut, squeeze your glutes, tuck your tail, tighten your abs, and strengthen your core.  If you have upper back pain and a sunken chest, you will be told to pinch back your shoulder blades, strengthen your scapular retractors, stretch the chest, and raise the sternum, until you look like a rooster.  Before running off to do these exercises, let’s see what the studies have to say about the link between pain and posture.

In one study, researchers looked at the posture of teenagers and then tracked who developed back pain in adulthood.  Teenagers with postural asymmetry, thoracic kyphosis (chest slumping) and lumbar lordosis (overly arched low lack) were no more likely to develop back pain than others with “better” posture.

Another study looked at increases in low back curve and pelvic angle due to pregnancy.  The women with more postural distortion were no more likely to have back pain during the pregnancy.  Another study found that adults with lumbar scoliosis and increased low back curve were no more likely to have back pain than others.  Other studies have shown no association between pelvic asymmetry, sacral base angle and low back pain.  Leg length inequality seems to have no effect on back pain unless it is more than 200 mm (the average leg length difference is 5.2 mm).  Hamstring and psoas tightness do not predict back pain, and there is strong evidence that orthotics do not prevent back pain.

These results are particularly striking given that many studies have quite easily found other factors that correlate well with low back pain, such as exercise, job satisfaction, educational level, stress, and smoking.  Although some studies have found a correlation between back pain and posture, it is important to remember the rule that correlation does not equal causation.  It may be that the pain is causing the bad posture and not the other way around.  This is a very likely possibility.  Studies show that patients will spontaneously adopt a different posture when injected with a painful solution (big surprise!).  I think these researchers should have won a major prize.

Based on the above, there is little evidence to support the idea that we can explain pain in reference to posture or that we can cure pain by trying to change posture.

Disc Degeneration and Other MRI Abnormalities

Another common idea is that herniated discs or other degenerative changes revealed by an MRI are major causes of back pain.  If you have back pain and get an MRI or x-ray that shows degenerative changes near the area of pain, such as a bulging or herniated disc, the doctor will likely conclude that the pain is due to what is seen on the MRI.  The doc may even recommend surgery to correct the structural defects.  However, numerous studies show that many types of structural abnormalities are poor predictors of pain.

In one famous study, MRIs were performed on subjects who did not have back pain.  Fifty two percent of the subjects had at least one bulging disc or other MRI abnormality for which surgery is often recommended. In a study of pain free hockey players, seventy percent were found to have abnormal pelvis or hip MRIs, and fifty four percent had labral tears.  Studies of active baseball pitchers or overhead athletes consistently demonstrate very large percentages (over seventy percent) of torn labrums and rotator cuffs.  Another study showed forty percent of pain free overhead athletes had partial or full thickness rotator cuff tears.  One third of asymptomatic people over the age of forty have rotator cuff tears.  These people have full pain free shoulder function.  MRIs on asymptomatic knees show that thirty four percent have tears of the meniscus.  Forty seven percent of professional pain free basketball players show articular cartilage lesions in their knees.  These are all issues for which surgery is sometimes recommended.

This is not to say that herniated discs, torn labrums or other structural abnormalities cannot cause pain.  Of course they can, and you would rather have less damage than more.  But if a large percentage of pain free people have bulging discs, then how likely is it that a bulging disc is the cause of your back pain?  If you look close enough at almost any joint in the body, you will find something wrong with it.  Don’t assume that whatever shows up on the MRI is the source of your pain.

Core strength

The idea that good core strength is essential for a healthy back is another ubiquitous idea.  If you go to a physical therapist with back pain and a midsection that is any less impressive than an Olympic gymnast, it is a mortal certainty you will be told to strengthen your core.  What is the evidence that poor core strength causes pain or that core strength exercises reduce back pain?

Before reviewing the studies, it is first interesting to note that most of life requires only minimal activation of the core musculature.  During walking, the rectus abdominis has an average activity of two percent of maximal voluntary contraction, and the external oblique operates at five percent.  During standing, trunk flexors and extensors are estimated to fire at less than one percent.  Add more than fifty pounds to the torso and they fire at three percent.  During bending and lifting muscular activation is similarly low.  Given that daily life seems to require so little core strength, perhaps it is not surprising that research interventions to increase core strength have little effect on pain.

For example, one study showed that core strengthening exercises for pain free persons identified as having a weak core do not reduce the future likelihood of back pain.  Numerous studies have been performed to test whether core strength exercises reduce back pain.  The thrust of these studies is clear – although these exercises can improve low back outcomes, it works no better than general exercise.  The obvious conclusion is that if core strengthening has any benefit at all, it works only because of the generally beneficial effects of exercise (or as a placebo), not because the core is a special area of concern.  In other words, despite what we are told over and over, the current evidence states that there is nothing magic about core strength as means to prevent or reduce back pain.  Of course, don’t expect to see any reduction in the number of fitness products that contain the word core.  In fact, perhaps I should change the name of this blog to Better Core Movement, or maybe The Core of Better Movement.

Conclusions

The above results are surprising and counterintuitive, and raise many questions such as: why do these approaches seem to work; how can so many people be wrong; and if these aren’t the true sources of pain, then what is?  I will try to answer some of these questions in the next post.  For now, I will say that all of the above approaches all share a fatal flaw – they look for the source of pain in the mesoderm, the structure of the body, when pain is in fact in the exclusive control of the ectoderm, the nervous system.  I’ll look at that issue a little more in my next post.

*Most of the studies referenced in this article are from three excellent papers: The Myth of Core Stability by Eyal Lederman; The Fall of the Postural Structural Model in Manual and Physical Therapies by Eyal Lederman; and The Traditional Mechanistic Paradigm in the Teaching and Practice of Manual Therapy: Time for a Reality Check, by Frederic Wellens.

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33 Responses to “Back Pain Myths: Posture, Core Strength, Bulging Discs”

  1. Todd,

    Have you read that article, “The Myth of Core Training”?

    • Matt,

      Thanks for stopping by. I’m not sure I have read that one. The research in my post is mostly from a great article by Eyal Lederman called the Myth of Core Stability.

  2. Hi, Todd. Nice post. You’d probably appreciate one of my articles on this topic:

    http://SaveYourself.ca/structuralism

  3. Todd,
    I’m always interested in, and enlightenedy by, your postings… even when I think I disagree. As you say, it certainly seems to make sense, from an observational point of view, that, e.g., tight hip flexors and weak glutes from excessive sitting would cause pelvic anterior tilt, leading to low back pain. In my own case, mild back pain from walking uphill stopped completely not long after I switched to a stand-up desk.
    Is there something special about the back such that structural imbalances are not the cause of pain, when in other parts of the body they obviously are (e.g. bursitis from internally rotated shoulders)?
    I’ll definitely look into those studies you mentioned.

    • Glenn,

      Thanks for the comments, appreciated as always. I agree its hard to believe structural issues don’t seem to matter much in the studies. Once I learned a little more about pain science it made a little more sense. I will discuss it in the next post, but the basic idea is that pain is an output from the brain, not an input from the body to the brain. The brain has quite a bit of discretion in deciding when you will feel pain, and its outputs in this regard are very individual and idiosyncratic and depend on many factors aside from the condition of the body, such as emotions, past experiences, future needs, etc. And that applies to the shoulder just as much as the back.

  4. I look forward to the next post!

    While all of this fascinates me, I can’t help thinking of how much the brain-centered approach you explicate reminds me of when I was kid. My Dad–a tough guy from the old country (Germany)–used to dismiss my minor injuries and pains by saying “Eh… it’s all in your head.” That was fine, until I actually fractured my ankle!

    Maybe its because I have lots of friends who are natural bodybuilders, and because I do powerlifting myself, that I appreciate the incredible role that the mind plays in the mind-muscle connection. But at the same time I see that bones, ligaments, tendons, fascia, and muscle have a palpable size, integrity and, well, structure, that the brain can’t simply change at will. But there’s definitely a lot more to all this that we need to think about!

    Thanks for making us think and wonder.

  5. Glenn,

    Its true, pain is all in your head, but not in the sense that it isn’t real. Pain is real. And yes, the body is important too, you will never lift a lot without a strong structure.

  6. Fascinating. I have pain in my lower back, but only when I run a lot. I also have pain between the shoulders and in the neck. So I’ve started my quest to find out why this is.

    I’ve been to chiropractors and physical therapists and they either have no idea what to do or say that I should strengthen and stretch certain muscles. I’ve not really bought the strengthening/stretch theory so I’ve continued exploring new therapists that might have other ideas. Right now I’ve met a therapist that practices the Feldenkrais method. I’ve decided to give it a serious try. Do you know much about Feldenkrais? What do you think about it? Atleast it seems to be more about the nervous system than about strengthening and stretching.

    I’m definately looking forward to your next post.

    • Tim,

      Sorry to hear about the pain. I am a big fan of feldenkrais and in my second year of training to be a practitioner. I have several other posts which discuss the Feldenkrais method. My take is that FM aims directly at the nervous system and therefore has a better chance of hitting the target than stretch and strengthen regimes, which aim at the mesoderm. Good luck!

  7. Todd , you make some excellent points…If you go to a physical therapist with back pain and a midsection that is any less impressive than an Olympic gymnast, it is a mortal certainty you will be told to strengthen your core.
    Brilliant! However every ‘fitness’ magazine seems to have a man lifting up his tee shirt to expose such an abdominal wall…bizarre

    I am a UK physio therapist with the emphasis on the latter ….I have been communicating with Eyal Lederman for many years. His work , articles and books are excellent but they are like much of this stuff counter cultural. Biomechanics is simplistic , it makes sense to most people, both in the general public and in much of medicine but as Paul has written -its usually wrong!
    You might be interested in Sandra Blakeslees very readable book on body mapping which is the missing link for explaining a lot of therapeutic input in my opinion.
    Great work

  8. Todd – looking forward to your next post because I have a central bulge at L4-L5 and get shooting pain down my legs. I am getting a cortisone shot in a few days. Things have been getting better, but it can, at times, be debilitating.

  9. Todd,

    GREAT post! I was going to ask you if Feldenkrais “jived” with this ectoderm approach. But then just read all the comments and got my answer 😉

    In all my years of going to seminars, workshops, accupuncture school, etc etc….I was most impressed with Feldenkrais. One of my very high level martial arts teacher who was from Israel, introduced a bunch of us to some basics. It was eye opening.
    Again great post.

    Marc

  10. Mri Scan is clinically FALSE -75 % useless,surgeries are 100% ineffective ,chirop/Ostep.etc uselerss ,especially in chronic conditions .Dr Sarno is spinal layman = idiot !

  11. NO DOCTOR NO MASSAGES NO CHIROPRACTOR NO
    SHOT’S INJECTIONS SURGERY’S ETC ETC IS GOING TO FIX YOUR BACK ENOUGH IS ENOUGH ONE’S YOUR BACK GO’S YOUR SCREWED FOR LIFE, DEPRESSION ANXIETY AND BEING MISERABLE FOR LIFE THAT’S IT YOUR DONE GET USE TO IT EVEN THOU IT’S HARD TAKES A TOLL ON YOUR LIFE THAT’S THE WAY IT IS FOR ME FOR 13 FREAKEN YEARS.

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