The Role of the Transverse Abdominis in Low Back Pain

me1 Today’s guest post is written by Harrison Vaughan, PT, DPT.  Harrison is a physical  therapy practicing in South Hill, VA at In Touch Therapy.  His professional interests include clinical diagnostic tests and treatment consisting of orthopedic manual therapy, predominantly spinal manipulation.  Harrison previously contributed an excellent article on the QUADAS tool to assess the quality of research on studies examining the efficacy of clinical examination tests.

Transversus Abdominis: Are we on the right bandwagon?

ta2 Many physical therapists base their low back pain treatments around strengthening the transversus abdominis (also know as the transverse abdominis, or TrA) muscle for stability.  Strengthening of the TrA is often incorporated in treatments with a wide variety of patients with a wide variety of pathology.  However, what really is the dysfunction that we are trying to manage and is this really effective? 

 

What does Transverse Abdominis do?

The function of the TrA is to stabilize the pelvis and low back prior to movement of the body. It acts within a feedforward bilateral muscle activation rationale from spinal perturbations with everyday activities. Rehabilitation is typically aimed at restoring motor control of this key stabilizing muscle. Literature points to effective means of treating low back pain with trunk stabilization and strengthening of deep abdominal musculature to improve motor control1

Diane Lee gives a great description of how to activate the TrA through abdominal drawing-in maneuver (ADIM)2. However, how long does it take for someone to learn this and do you think they will really do this correctly and efficiently if they are pain?  It has been shown that teaching a patient to perform the ADIM maneuver can be time consuming and difficult.3

 

How effective is activating the Transversus Abdominis?

It has been shown that the TrA is activated after the deltoid (~50ms) with arm movement task studies with LBP patients.4 A recent study showed that during a volitional recruitment task for the TrA , induced pain was shown to attenuate the activity of the TrA.5  It has also been discovered that pain will alter a muscle’s role as an agonist or antagonist to control movement for protection through the pain adaptation model.6 This has also been demonstrated with many prior studies of reduced TrA muscle thickness with chronic LBP. In turn, the delay of TrA timing and optimal muscle activation is altered, potentially making exercises that activate it ineffective when pain is present.

If we abolish the pain, would motor control and activation of TrA resolve itself? There has not been any conclusive data to show that the spine is controlled less when the activation of TrA is changed and altered timing of the TrA leads to poor core stability. The feed-forward activation of TrA can be interpreted differently from a small study that showed 3 of 8 pain-free individuals did not have the feedforward responses in 70% of trials with bilateral arm tasks.7 Even prophylactically, the isolated muscle pattern in pain-free subjects is controversial.8 This goes to show further that low back pain is complex, multimodal and overall challenging to treat. 

 

Is a lack of strength or stability really the reason for the low back pain? 

ta1 Do we claim to ‘stabilize’ every patient?  A recent study stated that some patients are not unstable at all and showed that LBP patients actually have increased stability rather than decreased stability.9 Even if we feel a patient is unstable, how do we diagnose it as unstable?  Special tests to clarify this are inconclusive.  P/A force over specific segments of lumbar spine have been found to be useful to identify the segmental impairment.  However, will activating the TrA fix this? PPIVMs for extension & flexion have poor sensitivity values. A common test practiced is the prone instability test also giving poor diagnostic values.10  You might as well flip a coin to determine instability by the values. 

 

Some thoughts…

As musculoskeletal specialists, we have significant knowledge and a pertinent role in management of low back pain. We need to concentrate on teaching the patients how to control their symptoms independently.  To me, this means giving the patient tools to provide self-pain relief through therapeutic means.  Activating transverse abdominis stating it will give stability when everyday aches and pains arise just doesn’t seem feasible. The use of foam rolls, towel rolls or any other affordable methods can be very effective in not only giving relief, but obtaining joint motion and allowing an exercise program to be more advantageous.  If a treatment doesn’t give someone relief or change, he or she will not be adherent to it, consecutively, returning to health care providers and starting the sequence again.

Since low back pain re-occurs in 70% of cases depending on source, we may not be challenging this problem appropriately. I think having the transversus abdominus as an active component in the treatment is somewhat useful but not conclusive.  Pain relieving exercises and education need to be the forefront of each program so muscle activation can be optimal.

What are your opinions?  Do you get good results from concentrating on TrA as your main intervention?  If so, how effective do you find it and what is your approach?  Is there any technique or method that you would recommend others to try?

 

References

    1. Teyhen DS, Miltenberger CE, Deiters HM, et al.. The use of ultrasound imaging of the abdominal drawing-in maneuver in subjects with low back pain. J Orthop Sports Phys Ther. 2005 Jun;35(6):346-55.
    2. Accessed 3 March 2009. http://dianelee.ca/services/TRANSVERSUSABDOMINIS.pdf
    3. O’Sullivan PB, Phyty GD, Twomey LT, Allison GT. Evaluation of specific stabilizing exercise in the treatment of chronic low back pain with radiologic diagnosis of spondylolysis or spondylolisthesis. Spine.1997;22:2959-2967.
    4. Cresswell  AG, Thorstensson A. Changes in intraabdominal pressure, trunk muscle activation and force during isokinetic lifting and lower. Eur J Appl Physio Occup Physiol. 1994; 68: 315-21.
    5. Kiesel et al. Rehabiliation ultrasound measurement  of select muscle activation during induced pain.  Manual Therapy. 2008. 13. 132-138
    6. Lund et al. 1991. The pain adaptation model: a discussion of the relationship between chronic musculoskeletal pain and motor activity.  Can J Physiol. Pharmac. 69:  683-694.
    7. Hodges P, Cresswell A, Thorstennson A.  Preparatory trunk motion accompanies rapid upper limb movement.  Exp Brain Res 1999;124:69-79.
    8. Allison GT. The push – throw continuum and core stability – are Physiotherapists teaching the correct motor patterns? in APA National Conference – Sports Physiotherapy Australia. Cairns, Queensland, Australia: 2007.
    9. Hodges P, Van den Hoorn W, Dawson A, et al.  Changes in the mechanical properties of the trunk in low back pain may be associated wtih recurrence. J Biomech. In press.
    10. Cook C, Hegedus E.  Orthopedic Physical Examination Tests: An Evidence-Based Approach.  Prentice Hall.  2007.

Flynn, T. (2005). The Use of Ultrasound Imaging of the Abdominal Drawing-in Maneuver in Subjects With Low Back Pain Journal of Orthopaedic and Sports Physical Therapy DOI: 10.2519/jospt.2005.1780

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24 Responses to “The Role of the Transverse Abdominis in Low Back Pain”

  1. Dear Harrison,

    Thank you for your article. I think that the importance of the m.TA is hugely overrated. Literature that covers inguinal hernia operations show no correlations with low back pain, while the m.TA is dysfunctional for a longer period. Another very interesting study was in the Netherlands where I am based among 800 pregnant women with low back pain. They wanted to see how low back pain develops postpartum. We all know that the muscles take 4 tot 8 weeks to recover before they become functional again. Almost 600 women quit the trial 1 week postpartum. Reason? Low back pain was gone, while the m.TA was not restored in function yet.

    There is NO study that proofs that segment stabilising exercises actually perform better than any other way of moving (primary outcome should be pain and dysfunction). A daily walk will do the trick. If instability of the spine exists than stability would be a harmony of co-contraction where speed, power, duration and order of dozens involved muscles that will change per millisecond and differ with any change in posture. The idea that a training of a single muscle, the m.TA will compensate for all of that is just ridiculous.

    I never train the m.TA and my results are on par with my colleagues, but I have the results faster.

    Grtz, Jan

  2. I would have to absolutely agree with Jan that attention to TA muscle activation is very overrated. LBP is very complex due to the nature and amount of pain producing structures. LBP and its origin, if not directly dealt with will inhibit TA function and patient compliance anyway. Introducing exercise too soon is perhaps why our profession misses the target and people go elsewhere for pain relief. Identify the source of the dysfunction and use a combination of all manual modalities to correct the identified issue. Muscle re-education can be a part of the whole treatment program, but should be introduced in middle to later stages of rehab in my opinion. Sharon

  3. Christie Downing, PT, DPT, cert MDT Reply April 27, 2009 at 5:21 pm

    Very good post, Harrison.

    The myth that the TrA can be isolated and the whole “core stability” mantra are the biggest whores (sorry to get so vulgar)in the PT world, in my opinion. It’s trickle down effect into the world of strength, conditioning and personal training have made me spend countless hours reprogramming patients who think that the solution to their sciatica is get their “core” strong.

    I use the word “whore” to imply how this whole concept has “gotten around” and it’s blanket application to all patients with low back pain has killed our critical thinking skills as clinicians.

    I believe it was last months PT journal that discussed at length the fallability of the core stability paradigm. To reiterate, definitions remain poorly defined, theoretical components are often unvalidated (or down right unproven as Jan implies). Controversy remains as to whether “bracing” “abdominal drawing in maneuver” or “motor control” are superior to one another (and no one has ever been able to definitively define and demonstrate the differences to me in the first place).

    However, we do know this:
    cross sectional muscle area is limited in those with low back pain, timing is altered in feedforward mechanisms in those with low back pain.

    Yet, we have done a poor job:
    1. Establishing a cause effect relationship
    2. Whether the dysfunctional timing causes pain or whether pain causes altered timing
    3. Whether correciton of the musclar function leads to improved outcomes.

    Do I ever use core stability? Yes…do I use it in all my patients?…heck no…I’d say barely a quarter. My first line of defense is always to classify a patient with back pain. Reducible derangements are treated with direction specific exercises, central sensitization with pain education, graded exposure to activity and perhaps some nervous system mobilization.

    For those without directional preference, I tend to follow treatment based classifications. If they fall into the “stabilization” category, I do tend to do this. However, even Fritz’s research on TBC with matched treatments really rendered an outcome of about 50%…rather mediocre in my opinion. What’s worse is that there is so far, no predictive abilities of those who fall into this classification. At least with the McKenzie method for those with derangements that centralize with direction specific movement, we can be fairly confident that the vast majority will be significantly better in two weeks…or on the flip side that those who do not centralize are anticipated to have poor outcomes.

    In any case, the blakent application of core stability and muscle reducation programs for all patients has really made us no more than personal trainers. What has happened to critical thinking?

  4. Trevor Winnegge DPT,MS,OCS,CSCS Reply April 27, 2009 at 5:49 pm

    My feelings on transverse abdominus training are that I include it in a program for lumbar hypermobility treatment, but I do not make it the showcase muscle to train. It is well documented the role of TrA in conjunction with diaphragm to help increase intraabdominal pressure during movement tasks (Hodges, Journal of Physiology, 1997 is a good article). It is also documented the effect of increased abdominal pressure on the lumbar spine. That fact alone, I feel it is necessary to include it into a comprehensive lumbar hypermobility treatment regimen. I feel with its attachments in so many different places-diaphragm/costal cartilage, thoracolumbar fascia, anterior 2/3 of the inner lip of the iliac crest and the inguinal ligament-why not train it with your program? I think leaving it out all together from your training regimen is detrimental, but I also think making it your first focus won’t really help either. Just another tool for the PT LBP toolbox. I also think a lot of PT’s misdiagnose LBP and may be overutilizing TrA training, instead of addressing the primary impairments first!

  5. Trevor Winnegge DPT,MS,OCS,CSCS Reply April 27, 2009 at 5:58 pm

    Christie-
    what do you do after you take someone with a reducible directional derangement and rid them of their pain? Do you add any ther ex at that time?I completely agree with you in that not everyone needs stab! I ask you this though-would it be detrimental to any patient, when they are pain free to increase strength of their core stabilizing structures? that may seem like I am a proponent of blanket stab, but I assure you I am not. I do like to treat a disc dereangement with manual techniques and positional based ther ex first. At the end stage of their rehab, however, I do employ the more functional stab exercises. What do you do at that stage of rehab? how do you feel about the “back schools” or “spinal programs” where patients receive no manual PT and simply lift boxes, and do stab execises for a few hours a day???? that may be a debate for a whole other day!!!!!!! Great conversation with this post Harrison!!!!

  6. Christie Downing, PT, DPT cert MDT Reply April 27, 2009 at 7:22 pm

    I do not do any further trianing with people who have a completely resolvable derangement…meaning they can tolerate end range flexion (or whatever was the causitive movement), repetitively, without reoccurance of symptoms or obstruction to movement and that they can return to their desired activity pain free. I make the restoration of function as specific to their goals as possible. Usually that means showing them how to do it with good body mechanics (which in my opinion is enough to turn on the core in most patients). I’d rather put someone on the treadmill if they are a runner or cycle for 10 miles if that is one of their primary activities as opposed to making them balance on a ball. In all, I find that those with reducible derangements who understand what to do to prevent reoccurance and what to do should it happen anyway, rarely or never need to return to me. Giving this group of people “stabilization” exercises is, IMHO, medically uncessary and unproven treatment. Yet, for patients who subscribe to this mantra and actually list it as a goal for them to get their “core strong”, I certainly educate them about the lack of validity of the core stabilization theory (well, rather I just ease their concerns about it) and rather than COMPLETELY crush their belief system (a big no-no), I’ll throw in a few exercises for them to do if it helps them feel more empowered.

    however, in those who seem to plateau (still have some lingering symptoms) with direciton specific exercises and manual therapy, there is a point that one must “get on with it.” This is often a point I induce core stabilization…not so much that I think it will get them better, but more or less to encourange activity, reduce fear and test the “stability” of the reduction.

    I really have no use for back schools, I’m constantly educating my patients and make it as individualized as possible. We had a formal back school at one point and discontinued it. Everyones said they were learning everything from their PT.

    As far as work hardening program (ie, lifting boxes)…there’s often a group of patients who need this…for training and restoring funciton for their job. But more often than not, I think it’s to reduce the fear of return to work. I’m not necessarily convinced these funcitonal training programs are continuing to make any further mechanical improvements. The real issue here, IMHO is reducing fear avoidance behaviors through graded exposure to activity. But then again, I don’t do work hardening, so anyone who does probably has a better foothold in this part of the arguement than I. In all, I think it’s an important part of recovery when I cannot replicate someone’s work setting in my clinic.

  7. I liken the TrA in low back pain to the VMO with patello-femoral pain: initially do some work it to get it firing, but once you fix the biomechanics of the movement it should be recruited on its own. The TrA doesn’t work in isolation in our ADLs, so why would we do extensive rehab on it in that way?

    Chris

  8. Trevor Winnegge DPT,MS,OCS,CSCS Reply April 28, 2009 at 9:04 am

    Christie,
    Interesting points-as always! Interesting to hear your perspective from the mckenzie point of view. What would you do for a higher level athlete who wants to return to sports with twisting-like tennis, hockey or baseball? I am also very curious to see what Mr Mike Reinold has to say on this matter, with his professional athletes. Mike-when rehabbing a pro baseball player, do you incorporate stab exercises? Just do manual?

    I think for most people, as soon as they are painfree, they wont do their home exercises for core stab anyways!!!!! so it may all be a moot point anyways!!!!!

  9. I think you always have to look at athletes a little differently…first, because the placebo effect is so high in this population, but second that their bodies are asked to function at end ranges and to be able to respond quicker. That being said, some sort of functional training is required that goes above and beyond the average person or even the recreational athlete. I would think, however…and this is pure specutlation on my part, that it really becomes proprioceptive traning more than anything else…and doesn’t really “stabilize” the spine per see, just allows it to respond more quickly at appropriately.

  10. I too would like to see Mike’s response to this interesting discussion. Not only for athlete’s with low back dysfunctions but for shoulder and knee patients as well. How does this translate to what we have been preaching with core stability exercises throughout return to play rehab for shoulder patients, knees, etc.?

  11. Dr. Davon Jacobson, MD Reply April 30, 2009 at 10:54 am

    This is really a well laid out website. I like how you have presented the information in full detail. Keep up the great work and please stop by my site sometime. The url is http://healthy-nutrition-facts.blogspot.com

  12. OK, maybe this is a little silly, but certainly pertinent to our discussion:

  13. gotta love the office!!!!!!!!

  14. I hope we have not thrown out neuormusular training/strengthening completely!!!

    Sure the TrA thing, clinically I don’t have a real time US unit at my disposal…can’t say I have figured it out in isolation.

    But to say that the practice of working on “core stability” and neuromusclular control is unecessary is going too far.

    Julie Hides has done a nice job of making a good case for multifidus in her Spine articles(94, 96). And the 2001 article does support prevention of recurrance through such training. Just in 2008 in Manip Ther she was able to show unilat CSA deficits in the chronic population as well.

    OSullivan’s neuromuscular control approach (ref #3 above) shows where we need to go with some of these subpopulations. …Beyond lying on the back and “dead bugs”.

    As far as the athletic population…rehabing the full kinetic chain including the lumbar spine/pelvic girdle on ALL my athletes has served me well. This is especially true in those who have been unsuccessful with prior rounds of PT that look local only. Or those who blew out their ACL 2 year ago and now have shoulder tendonitis.

    I will plank till the end!

  15. Amy,

    Although the work of Hides and O’Sullivan is fascinating, there has been no evidence that low back pain will gain from it. I saw Hides during a convention last month and asked her for proof of curing backpain, she had none. Segment Stabilizing Exercises only provide results if the control group is passive therapy. Al the wonderful research should stay in the laboratories, not in our clinics.

    Don’t believe we should throw out everything concerning the TrA, but we should not give it anymore attention than we do other structures.

  16. Trevor Winnegge Reply May 2, 2009 at 6:08 am

    I think Jan makes the best point here…..”Don’t believe we should throw out everything concerning the TrA, but we should not give it anymore attention than we do other structures.” TrA should simply be another tool in our toolbox. I liken the recent TrA craze to the VMO of the knee. Is VMO training important for a knee patient-sure it is. Would we get a patient better if we only focused on the VMO, and neglected other hip and knee musculature? of course not! take TrA strengthening for what it is-another muscle you can add into your core training programs. Like Jan said, let’s not make it the end all and be all of eliminating back pain!

  17. I have been watching and enjoying this discussion, every time I wanted to jump in I had to run!

    This is why I love these discussions and this forum for us to all interact – collaboration. After reading through all of these comments, I think we are ALL right! I never advocate one absolute method to treat, it appears that combining everything that has been discussed here may be the best option.

    No, focusing on the TrA as primary treatment will not yield results. This is because the problem is multifaceted. The TrA and “core” training etc is just a part of the puzzle. Agree with the comments above that say, “why not include TrA?” I would still train the “core” (whatever that may mean…). Why not? Wouldn’t any type of physical activity and increase in strength help our patients?

    In regard to athletes, training the core is important. That being said, it comes down to the definition of “core.” Crunches are not an athletic core training movement. Athletes need two things from the core:

    1. Rotary power – sports depend on the athletes ability to separate their hips from their shoulders (i.e. trunk rotation). Look at the model of a hitter or golfer, they need to stabilize their legs, rotate their shoulders against their hips, and then explode back and through. Need to enhance rotary strength in my mind.

    2. The core serves as a transfer of energy. This has to do with the above as well, but in many athletes, energy is developed in the lower extremities and transferred into the upper extremities. This has to transfer through the core, either through rotary power of through stabilization to not allow “energy leaks.” Meaning, maintaining a stable core without relying on end range of motion of your lumbar spine or pelvis (i.e. locking in extension because your core function is poor) for stability.

    I think you can apply these concepts to all patients as a part of normal functioning, but to a much smaller degree.

    What do you guys think about how I defined the need of the core in athletes? How would you alter or add to my thoughts?

  18. Harrison Vaughan, PT, DPT Reply May 2, 2009 at 9:36 am

    All,
    Thanks for the kind words and great discussion on this debatable topic! I agree with Mike that everyone seems to be on the right page as a whole. It is very interesting to read everyone's approach as nothing is set in stone related to treating this condition.

    There will always be an argument on the best route, including some individuals stating every patient needs to strengthen pelvic musculature, perform proper breathing techniques with the diaphragm, etc etc as it is all related and connected to the LB. Does this mean I get a guy to pull his ***** up!? Ha…no!

    We, as physical therapists, need to know the means of diminishing pain with a cause & effect approach as main path. As many of you all know, once the horrendous pain diminishes, each pt has a totally different demeanor, personality and quality of movement. Are these pts able to walk, vacuum, clean the house, pitch, run, etc due to increases in strength over a 2 wk span…doubtful per exer phys guidelines.

    This is what can really separate us from personal trainers, yoga instructors, etc. in that they don't have the 7 yrs of education to do this properly. (On a side note, in the state of VA but unsure of other states, it is LEGAL to advertise that you perform physical therapy even if you are not a licensed physical therapist…very disturbing). Also, physicians really don't have the proper means of fixing LBP other than medication so we need to be on the top of the chain as main caregivers.

    It is unfortunate that as the economy recesses and healthcare reimbursement drops; I see that pts self-discharge or time-frames for insurance ends once pt is out of pain prior to really being able to "increase core stability" to the extent it needs to be for me to be happy and sure that symptoms will not arise again. What will really happen in the future…duration shortens, reimbursement drops to the point of not coming out on top??

    I really enjoy the quotable articles in the posts above and I even include in my article. I am an advocate for evidence based practice, but honestly, it is 10 yrs behind clinical practice (a prime example is recent study on PT better than Sx for OA of knee: Going into the knee surgically does not just remove bad cartilage but takes away good stuff too…No brainer. I feel we can all learn from each other well, if not better, than EBP to not only make us better clinicians, but more importantly, to give the best care for our patients.

    On that note, continue the excellent discussion points as Mike has taken technology to great heights to improve our field of physical therapy.

  19. Putting Health Back into Fitness Reply May 3, 2009 at 4:41 pm

    You guys that are responding are brilliant..i’m not a PT, but even with the clients i train as a personal trainer/fitness coach, i avoid reductionist approaches, pegging things on one muscle, and looking to over-stabilize certain parts of the body. I’m not the brightest bulb on the shelf, but i have a feeling that when the body is aligned and the movement quality is there, then pain will be less likely to pop up. No one client is the same and protocol-oriented approaches like TVA activation exercises seem to be a fear response used by those who don’t understand that the body works as a unit.

    I am a certified postural alignment specialist through the Egoscue Method, and have had great results with my clients getting them out of pain by giving simple exercises to help re-align their joints and getting their bodies to be more functional. Have you guys done any postural education or postural exercises with your clients?

    Charlie Reid B.S., CSCS, CPT, PAS II

  20. Hi everybody,

    Glad to see that everybody is responding so constructively. I have to respond to Harrsion with his take on EBP.

    Sometimes EBP is 10 years behind clinical observations. There is one problem here. Our own observations and reasoning are limited. If I’d to accept my own observation as the norm, the sun would revolve around the earth and I would be back in the medieval ages. We have clinical for thousands of years, but we are really curing people the last 100 years. This has everything to do with embracing the RCT’s that will help us to avoid bias and coincidence.

    From a clinical point of view I would start with level A evidence. If that doesn’t work, I would go to level B. If it all doesn’t work, then you start experimenting on your clients (that’s what it is, even if it is educated clinical reasoning).

    On low back pain, all evidence is still pointing to the discs. Although we tried to move away from it with the pelvic stability model (Snijders, Vleeming, etc) and the rest of the lumbarstability model (Panjabi, hodges, richardson, hides, etc.) or the combined lumbarpelvic stability model, we end up back to the discs.

    Although posture and wrong movement patterns will influence the asymmetric pressure on the disc. The quality of the disc is mainly genetic in nature (Battié 2009). If you still think that non-specific low backpain has nothing to do with the discs, you have some reading to catch up.

    An it’s true that patient with (chronic) non-specific lowback pain have problems in their feedforward mechanism. The problem is we don’t know whether this is causal. It is likely that muscles contract later, just to minimize the pain. In that case, working the TrA is not your first priority.

    As I stated earlier, I never do anything specific with the TrA in my patients and my ‘success’ record is on par with any colleague I know. The funny thing is that every review will predict this. The only thing is that I do it cheaper, with less effort (training the TrA is timeconsuming, even frustrating).

    On the subject of athletes, I believe that optimal movement patterns will minimize the energy leaks, Mike is referring to. Biomechanics in sports had proven it’s value. But in even then, the core would be just a another link in a chain. A tennis player will transfer the ground reaction force to a smash through the core. But the legs and the core together will be responsible for only 50 percent (Groppel 1992) of the transfer. I still believe we put to much effort in a few muscles.

  21. Phil Page, PT, ATC Reply May 7, 2009 at 3:51 pm

    Undoubtedly, chronic low back pain can be caused by a number of musculoskeletal pathomechanics, just as we see in chronic shoulder pain, knee pain, etc. The late Vladimir Janda MD identified his specific patterns of muscle imbalance as one possible mechanism in CLBP. Janda first speculated that the TrA was prone to weakness and motor control dysfunction in chronic low back pain, which was subsequently substantiated by the Australian researchers. While Janda influenced researchers at Queensland University, he pointed out that in-fact, the TrA functions in a reflexive feed-forward mechanism, and voluntary training (ie Abdominal Hollowing) is likely neither functional nor effective. Unfortunately, the media inflated these ‘miracle’ research findings of the TrA, spreading its myth as the “key” to curing CLBP in numerous news articles, which many clinicians also accepted as gospel.

    The TrA likely does contribute to core stability, but not in isolation. Through its insertion in the thoracolumbar fascia, it definitely can influence lumbar stabilization. Recently however, Canadian researcher Stuart McGill PhD has refuted the claims of the TrA as a primary ‘core stabilizer,’ noting that biomechanically, no single muscle can dominate core stability (Kavcic et al. 2004, Spine 29(11):1254-65). Later, McGill’s lab found that the abdominal hollowing maneuver contributed little if any to spinal stability (Grenier & McGill 2007, APMR 88:54-62), finding instead that bracing of the entire abdominal region improves lumbar stability. Therefore, the argument that TrA training is “stabilization” training is completely false. In fact, researchers from western Australia recently published a short and critical discussion on the topic of TrA as a core stabilizer (Allison & Morris, 2008, Br J Sports Med 42:930-31).

    In summary, it appears that the TrA is not as much of the ‘holy grail’ as we had previously thought. It obviously is not an isolated core stabilizer, but likely involved as part of the entire ‘pelvic chain’ to help provide core stability, rotary force, and force transmission with the other abdominal muscles, multifidus, diaphragm, and pelvic floor. As with many motor control dysfunctions, we are very limited in our knowledge and technology to assess and treat chronic low back pain from a functional perspective. It is still important to assess TrA function as part of the phasic chain of muscles prone to inhibition to identify the presence of Janda’s muscle imbalance syndromes; however, as Janda stated, training it voluntarily as with abdominal hollowing, is not functional. The TrA should be integrated in movement as it functions in a feed-forward mechanism.

    Phil Page, PT, ATC

  22. What inhibits the transverse abdominus?

  23. Geeze Transverse Ab is so 1999, come on guys. Even O’Sullivan (whom is cited above) admits he was wrong.

    See this video of him admiting as much: http://www.youtube.com/watch?v=YezBG_NdLgs&t=8m0s

    I think there has been a general conflation on the part of sports physios to conflate performance with pain. There is a general lack of evidence of such correlation.

    Lets get with the times guys. Break out of your bio-mechanical functional fixedness.

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