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Understanding the Mid-line

The much misunderstood “core”. It might be the most misunderstood structure in the body. There is no way that I can make a real dent on the whole subject in one short post but hopefully I can elucidate you in some small way.

When the average person thinks of “core” (which is actually a great term which has unfortunately been bastardised to the extent that it actively annoys me) it’s usually just abs on their mind. Which is fine, abs are cool, they look great and the 100% have a role to play in performance and aesthetics.

BUT,

Abs and core are not synonymous.

You know that the core is way more than that. When I think of what core training involves I block it as everything above mid thigh and everything below the shoulders (abdominals in the front, paraspinals and gluteals in the back, the diaphragm as the roof, and the pelvic floor and hip girdle musculature as the bottom, inside all of this there is 29 separate pairs of muscles that help stabilise the spine and pelvis (2)). Another way to look at is everything that isn’t peripheral. Whilst I like to define it as above (mid-thigh to shoulders) for ease there is a very strong argument, which I wholeheartedly support, to include the muscles of the jaw and neck into the core, the reason why I’ll cover below (way below, I can already tell I’m going to get carried away.)

Before I go any further into it though what the core is we need to define it’s role as best possible within the confines of this article.

THE ROLE OF “THE CORE”

Whilst there is no common consensus on the exact anatomy, physiology, and methods of how to evaluate a clients “core” functionality, the role on the core is undeniable in terms of proper load balance in the kinetic chain, maximising a persons functional range of motion (proximal stability = distal mobility (7)), providing a base of support for maximises force production as well as protecting the joints by decreasing/minimising joint load, shear, compressive, and translational forces throughout the body (1,2).  From a performance point of view it’s easy to see that there is a huge benefit from training “core stability” but one of the most common pathologies we come across as coaches is a client with lower back pain.

Punjabi has described clinical instability (i.e. instability when there isn’t a structural defect cause which may necessitate surgical intervention) as “the loss of the spine’s ability to maintain its patterns of displacement under physiologic loads so there is no initial or additional neurologic deficit, no major deformity, and no incapacitating pain”(3). Clinical lumbar instability in this sense has been cited as a significant cause on lower back pain (4, 5). A meta-analysis of 39 (this is good) randomised trails that investigated treatment of chronic low back pain of non-specific origin with an exercise intervention found a “beneficial effect for strength/resistance and coordination and stabilisation exercise programs over other interventions (6). It’s worth noting in the same meta-analysis that they found little to no benefit from combining the strength/resistance work with “cardio”. From a purely anecdotal point of view with evidence I’d suggest that this is down to people losing pelvo-lumbar control when one hip is in flexion and the other extension (assuming that the cardio prescribed is running, x-trainer, cycling, swimming) and the stability in around the hips and lower back, so as you’re teaching a more stable, controlled lumbar and hip complex with the strength work you’re teaching a less stable/more unstable hip complex at the same time which results in a conflict of adaptation (the adaptation being what any intervention is actually about) and no real change hence no alleviation of lower back pain symptoms. Again, complete conjecture on my part and would need further study.

Riiiiight, I’m aware that this is getting on a little bit. So a really quick round up of this so far:

  • Core means everything which isn’t arms and legs (and even then it’s a little bit of legs).
  • Building a strong core is hugely important for increasing your CrossFit performances.
  • There is a statistically significant benefit on lower back pain from consistently performing core stability exercises.

More than Sit-Ups and the Breathing-Bracing Continuum,

Looking back to developmental movements when, as babies, you first started moving, the first thing that happened was you start wriggling around like a madwomen and learning to, at a very basic level, activate and control all the muscles above. To quote directly from the work of Kobesova and Kolar,

“This allows for basic trunk stabilization, a prerequisite for any phasic movement and for the locomotor function of the extremities.“(9)

So we know that not only is core stability a prerequisite for movement (from crawling, to walking, to gymnastics and lifting) but on top of that recent research into the “mind-muscle connection” shows that by  understanding what muscles we’re trying to activate, including there position and function, can improve the contraction and activation (10,11).

To start to delve into how we might address “core training” we need to move to a slightly more global view of what the core musculature actually does. As noted above above the core consists of:

  • abdominals and accompanying fascial complex in the front,
  • paraspinals (think lats, spinal erectors (lumbar and thoracic ), traps as a whole and rhomboids) and gluteals in the back (personally I’d like to include hamstrings in here as well),
  • the diaphragm as the roof,
  • the pelvic floor and hip girdle musculature as the bottom including
  • internal stabilisers of the spine and pelvis (External and internal obliques and Transverse Abdominus (TvA), Mulitfidus, Quadratus Lumbrum (QL), Psoas, Illiacus (preferably not to be thought of combined with Psoas (8)), and various ligamental structures that I’m not going into right now).

I’m our case we’ll move away from specific muscle action as soon as possible but before that we need to have an idea about what muscles are working and where they are so we can address bracing and core stiffness with some specificity as well as improved performance

*NOTE: It’s our responsibility as coaches to educate our athletes as much as will help them. I’m not saying they need to read something like this but whatever you can do to help them understand why they’re doing something is a big deal and will help create buy in and trust.*

When anybody talks about core stability a huge part of this can be perceived as “bracing”, defined as:

“anything which imparts rigidity or steadiness”

or

“to furnish, fasten, or strengthen with or as if with a brace.”

“to fix firmly; make steady; secure against pressure or impact”

“to make tight; increase the tension of.”(12)

Whilst it isn’t an exact comparison to what we’re talking about it nicely gets across the message that when we talk about bracing and core stability we are really talking about increasing rigidity,pressure, and tension throughout the body.

And here is finally where we can talk about application!!

When you ask most people who lift about bracing you get a lot of big breathes into the stomach, which is okay. It’s like having half the answer and is way better than hollowing which is, frankly, detrimental to sports performance (13). Application for you is tuning up or down the stiffness you’re creating as it’s applicable to you goal. If you’re doing a 2000m swim then maybe you don’t need to create the same tension as you would for a maximal loaded carry.

I know this isn’t super actionable, at least not straight away, but with some practice and consistent employment of the principles you can learn where and when certain levels of bracing is appropriate. More importantly you should now understand what you’re trying to achieve and why.

References:

  1. Kibler, W., Press, J. and Sciascia, A. (2006). The Role of Core Stability in Athletic Function. Sports Medicine, 36(3), pp.189-198.

  2. Akuthota, V., Ferreiro, A., Moore, T. and Fredericson, M. (2008). Core Stability Exercise Principles. Current Sports Medicine Reports, 7(1), pp.39-44.
  3. Panjabi, M. (2003). Clinical spinal instability and low back pain. Journal of Electromyography and Kinesiology, 13(4), pp.371-379.
  4. Delitto A, George SZ, Van Dillen LR, Whitman JM, Sowa G, Shekelle P, et al. Low back pain. J Orthop Sports Phys Ther. 2012;42(4):A1–57. doi:10.2519/jospt.2012.0301.
  5. Long DM, BenDebba M, Torgerson WS, Boyd RJ, Dawson EG, Hardy RW, et al. Persistent back pain and sciatica in the United States: patient characteristics. J Spinal Disord. 1996;9(1):40–58.
  6. Searle, A., Spink, M., Ho, A. and Chuter, V. (2015). Exercise interventions for the treatment of chronic low back pain: a systematic review and meta-analysis of randomised controlled trials. Clinical Rehabilitation, 29(12), pp.1155-1167.
  7. Mattacola, C., Kiesel, K., Burton, L. and Cook, G. (2004). Mobility Screening for the Core. Athletic Therapy Today, 9(5), pp.38-41.
  8. McGill, S. (2009). Ultimate back fitness and performance. p.78.
  9. Kobesova, A. and Kolar, P. (2014). Developmental kinesiology: Three levels of motor control in the assessment and treatment of the motor system. Journal of Bodywork and Movement Therapies, 18(1), pp.23-33.
  10. Calatayud, J., Vinstrup, J., Jakobsen, M., Sundstrup, E., Brandt, M., Jay, K., Colado, J. and Andersen, L. (2015). Importance of mind-muscle connection during progressive resistance training. European Journal of Applied Physiology, 116(3), pp.527-533.
  11. Critchley, D. (2002). Instructing pelvic floor contraction facilitates transversus abdominis thickness increase during low-abdominal hollowing. Physiotherapy Research International, 7(2), pp.65-75.
  12. Collins, W. (2011). Collins dictionary. London: HarperCollins.
  13. McGill, S. (2009). Ultimate back fitness and performance. p.75-76.

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