When I recorded my “Advanced Core Training & Conditioning” presentation for Muscle Imbalances Revealed: Upper Body, I included a thought process I had about what would be the best way to visualize how the core actually works. In between showing pictures of sprinters, gymnasts and people who have way more complex core training issues than 99.9% of the people on the face of the earth, I came out with the theory that seemed to resonate, enough so that James “Smitty Diesel” Smith tweeted to me that it was “freakin brilliant.” No small praise from someone who has pretty much seen it all and done even more.

Before I talk about my theory, I want to discuss a few other theories, as they’re some of the underlying things that lead to the theory being created.

Inner/Outer Core and Hoop Systems

This was a thought process first popularized by the Australian Method of core training that focuses on TvA activation, segmental stability, and more of a clinical approach. The Inner Core is designed as the TvA, multifidus, pelvic floor and diaphragm, muscles that aren’t sexy at all but extremely necessary. I mean, you’d never say to yourself “Hey, check out the transverse on THAT girl!! Woweee, I’d like to get me some of that stability!!” They’re the less showy muscles but the ones that directly attach to the length of the lumbar spine.

The outer core is made of everything else that directly impacts the core, such as the rectus, obliques, and also the lats, glutes, iliopsoas, and to a degree every single muscle that attaches to the ribs, spine, or pelvis.

What I don’t like about differentiating between the inner core and the outer core is that describing them like this is like saying they’re separate entities that can function independently. If we try to get just the left lat to fire on EMG analysis, you’ll also see every other muscle fire to a certain degree, especially if the person is standing upright and fist pumping the hell out of a BC Lions Grey Cup win last night. Can you train them separately? Sure, but that doesn’t mean that they’ll ever function independently when put to task. It is, however, a great method of defining more postural and movement-producing muscles and their roles together.

Balloon Core Theory

This was popularized recently by Mike Robertson, and shows how pressure or deformation on one aspect of the core (or balloon in this case) can cause an increase in pressure on another one. Additional to this, the greater the internal pressure if the structure, the greater the potential stability of the system if the muscles are forming a good casing around the “balloon.”

The downside to this theory is that if there is any inconsistency to the system, you would expect to see immediate injury, however in instances of rectus diastasis (where the abdominal fascia that connects one half of the six-pack to the other tears during child-carrying months in women), hernias, spinal injuries, or pelvic floor dysfunctions, the function of the remainder of the core can still operate, albeit negatively affected. Have you ever tried to put a small hole in an inflated balloon? It doesn’t go well.

On top of that, this theory doesn’t account for the difference in lines of force between the inner and outer core, or in the different lines of fascia that can dictate the force coupling relationships of the core. It also doesn’t explain mobility of the core, such as in dancers or gymnasts, and doesn’t explain the rapid force production through a jumpers legs into their body while still breathing through the development of force, but is more directed to strength athletes.

I do like the concept that force implied on one area is distributed to all areas of the core until a breaking point is reached, or until a source of energy leaks is encountered, resulting in injury,

Tennis Ball Theory

I came up with this because in all the time I’ve worked with clients looking to either decrease their pain, tighten their abdomens, increase their strength, move differently, and develop speed, the concepts out there weren’t holding up in all situations. McGill’s concept of SuperStiffness can’t work with a gymnast trying to develop a pelvic whip through a back handspring, or the counter-current movement of something like running, cross-country skiing, or anything that’s a repetitive motion.

 They also don’t explain how something like this doesn’t make you shit your kidneys out and have your spine disintegrate in front of your eyes.

The tennis ball theory fits well because it is fairly stiff and resilient, but can be deformed pretty easily. It’s elastic, meaning when a force is put into it, like the legs driving up, it can convert the energy in another direction, like through the upper body. That hip whip for the gymnast I was talking about fits well here.

The tennis ball isn’t one solid unit, but is a composite of a couple of pieces of rubber stitched together, and also has layers of material that bind in different directions to produce structure and stability.

Let’s say something happens and you wind up cutting into the tennis ball. The structure of the unit as a whole is still intact, and can still produce some force attenuation, but not much compared to an intact ball.

The ball can deform and be reformed, it can generate a lot of elastic energy, it can get damaged and then still maintain its shape to generate some force, and is made of multiple concentric layers stitched together. It seems to hold up to analogizing with the function of the core. To see more of these kinds of mental sticking points check out my Advanced Core Training webinar on Muscle Imbalances Revealed: Upper Body.

Now I like to learn as much as the next guy, so do you know of another core theory that you’ve seen that blew your mind away? Leave me a comment below and share the knowledge bombs for all!!