“Core” is one of those yoga and fitness buzz words that has become highly popularized as a fitness marketing trend (feel free to count all of the ads you see in one day that include the word core), spawning all types of studio names, fusion classes and fitness fads.  There was even a time when “working on the core” became the ubiquitous answer for all physical ailments.

Got back problems? Strengthen your core!
Not so good with balance?  Train your core!
Got shoulder pain?  Learn to move from your core!
Want to look good in that bikini? More core! Core! CORE!

Ok, you get the point. We are not saying that this information is useless (well… I might be saying that), but…. what the heck does all this mean???

The funny part is, the studies that have been done on the effectiveness of “core training” for reducing back pain have either shown no significant outcome or have been inconclusive. (1 and 2) Why? One reason may be that there is no universally accepted definition of what the “Core” actually is. Wikipedia tells us that the anatomical term means simply anything but our limbs (great, that was helpful). Most other fitness or physiotherapy related sources attempt a definition consisting of muscles surrounding the trunk: Transversus abdominus, External Obliques, Internal Obliques, Multifidus, pelvic floor… and sometimes other ones including: rectus abdominis, erector spinae, quadratus lumborum, psoas major, gluteus maximus, respiratory diaphragm…. blah blah blah. That’s somewhat helpful, but… doesn’t core generally mean center? Are we not more than hollow tubes? What are those things that fill the tube? Must be something in there… OH RIGHT, abdominal organs! But… what could organs POSSIBLY have to do with movement and “core” stability???


What actually creates trunk stability (or core stability) is Intra-abdominal pressure, or IAP. Most of your abdominal organs (you know, the stomach, small intestine, large intestine, liver, gallbladder, pancreas, etc.. with the exception of the kidneys and in some people half of the spleen) are encased in this fluid filled membrane called the peritoneum. Because the volume of the peritoneum hardly varies (of course if you just ate a gigantic meal, it will vary according to said meal), you can think of it like a big water balloon (with organs in it). When you inhale, your diaphragm moves downwards into this water balloon, pushing it down and out to the sides. If your pelvic floor is well integrated (if not… you should probably fix that, like NOW), then this balloon will also be stopped by moving downward into the pelvic bowl by the pelvic floor. If you further compress your abdominal muscles (the ones we spoke about above) we create IAP (think of compressing the sides of a water balloon). IAP is actually what stabilizes our spine and allows us to maintain posture during movement. This is one of the main reasons that we can walk on 2 legs for sustained periods as compared to other animals, who cannot create IAP. This compression of our bag of organs is actually what gives us core stability, and because it is linked to involuntary processes (breathing), IAP is automatically created before the limbs are moved into a challenging position (if you don’t believe me, ask a very pregnant woman to open a jar of pickles and ask her if she felt her tummy move first). It is incongruent to exclude the organs in a definition of the “core” when organ movement is an intrinsic part of  “core stability.”

Let’s go to some more studies. It seems that people who have greater diaphragm function (relative muscular strength and range of motion) are better able to create IAP (think about the water balloon) (3). It should not be surprising, then,  to find that professional athletes have greater diaphragm function. You might notice Olympic power lifers wearing belts around their abdomens, this is to assist them in creating IAP and aid proper breath and posture (again, it is all related because of this concept). This means the diaphragm has 2 functions, which are NOT mutually exclusive: Posture and breathing. So… does this mean that we can work on our breathing to increase “core” stability and function and we don’t have to do 100 crunches a day? YES! In fact, working on creating IAP will help you do your crunches, if that is what you chose to do instead of real exercise (tee hee).

So go and play with that information and in our next post, we will talk about… you guessed it, BREATHING!