When many people think about a strong core, they picture someone with “six pack abs” like this fine underwear model man right here. :) But our functional core is actually much more complex than this oversimplified notion, and whether your abdominals are super defined and underwear model-worthy or not says nothing about how strong your core truly is. And even if you’ve already learned about the fuller picture of our deeper core, it’s very likely that you have been practicing and/or teaching yoga with an over-reliance on the six-pack muscle without even realizing it.
The six-pack muscle (a.k.a. the rectus abdominus) is actually just the most superficial (closest to the skin) of our four abdominal muscles. It runs vertically along the front of the abdomen and when it contracts, it pulls the rib cage and pelvis toward each other, usually resulting in a rounded spine (spinal flexion) and/or a tucked pelvis (posterior tilt).
Our other three abdominals are deep to the rectus abdominus. The internal and external obliques run diagonally across the abdomen and are commonly thought of as muscles that rotate the torso. The transverse abdominus is our deepest abdominal of all, and when it contracts, it has a corset-like effect of compressing the entire abdomen inward.
MY ABDOMINALS ARE MY CORE, RIGHT?
No, your abdominal muscles are actually not your core - at least, not in and of themselves. Your functional “core” is actually made up of all of the muscles which stabilize your spine as you move - also often referred to as your “core stabilizers”. Depending on whom you talk to, this can mean up to 40 different muscles - whoa, man!!
Yes, your four abdominal muscles are part of this group, but your core stabilizers also include the multi-layered muscles of your spine, your pelvic floor musculature, your back muscles, your psoas (an important muscle you’ve probably heard a lot about which deserves a whole blog post of its own!), the muscles that stabilize your shoulder blades, and your respiratory diaphragm.
When all of these muscles are functioning well, they will successfully keep your spine stable and protected as you twist, squat, climb, bend over, lift heavy objects, and generally move your way through life.
Once we understand the interconnected role that this large group of muscles plays in stabilizing our spine, it becomes clear that it’s physiologically incomplete to treat the core as simply the abdominals, or worse yet, as just the superficial rectus abdominus. In fact, because it’s common for our sense of “the core” to be so narrowly-defined, there is often too much emphasis placed on working the six-pack muscle when we do our “core strengthening” exercises, resulting in many (many!) people who have visibly-defined abdominals, but weak cores.
WHAT IS THE BENEFIT TO HAVING SIX-PACK ABS?
While six-pack or otherwise flat abs are an aesthetic that our culture finds attractive, they actually offer no physiological benefit to our body. In fact, not unlike other body aesthetics that our culture idealizes (think high heels and that all-too-common overly-arched spine), creating too much tension in your abdominal area can actually lead to musculoskeletal imbalances which can contribute to health problems with time. Learning to wean ourselves off of the over-use of the six-pack muscle is therefore an essential step toward restoring balance in our body.
DO YOU TUCK YOUR PELVIS TO “PROTECT YOUR SPINE”?
We used to think that one of the best ways to “protect the spine” was to “engage the core” by tucking (posteriorly tilting) our pelvis via contracting our rectus abdominus. Although new biomechanics info has taught us otherwise, it’s still quite common in many yoga classes and in some schools of pilates to teach students to tuck their pelves throughout their practice. And surprisingly enough, teachers often instruct a pelvic tuck without even realizing it! Because most yoga teacher training programs don’t include much anatomy education, their students often ending up memorizing cues to teach during poses without understanding the anatomical action the cue is describing. Did you know that the instructions “lift your belly”, “tailbone toward your heels” and “tailbone down” are all pelvis-tucking cues?
We now know, however, that not only does tucking our pelvis not innately protect our spine, it also does not necessarily engage our core.
Because our pelvis serves as the base of our spine, its orientation in space directly affects the shape the spine. If the pelvis tucks, it causes our low back, which would otherwise have a natural inward (lordotic) curve, to flatten (hypolordosis). We now understand, though, that our natural spinal curves are actually crucial to our spine’s optimal functioning. They serve to “force-dampen” the effect that gravity has on our spine, and can be thought of as our built-in shock-absorbers. As much as possible, we want to preserve these natural curves and therefore the integrity of our structure by stabilizing our spine. (Update December 2015: This last sentence is a tad outdated now. It basically suggests that keeping a "neutral" spine is preferable all the time, and while this has been a very popular idea for several years, we're now realizing that this belief stems from looking at the body as though it were a two-dimensional structure, and also an innately fragile structure. Today I would write that it's important to keep a stable, neutral spine when our spine is under great load (think weightlifting), but in day-to-day life it's not a big deal to tuck your pelvis - we just don't want to live there (or in any one position) all the time. BUT yoga teachers DO cue way too much pelvis-tucking in yoga, treating it as an almost universal cue throughout all yoga poses, and we instead want to learn to cue a pelvic tuck only when the pose really benefits from it.)
But tucking our pelvis actually does the opposite of stabilizing the spine - it mobilizes the spine by flattening the lumbar curve (spinal flexion). And because the action of tucking our pelvis comes from the contraction of only our most superficial, “six pack” abdominal muscle, our true core wasn’t asked to work at all when we tucked.
THE BIGGER PICTURE
The big picture of core stabilization isn’t quite as black-and-white as this, and there are of course some instances in which we do want to work a posterior pelvic tilt. But the idea that we should “lift our belly”, “move our tailbone toward our heels”, or otherwise tuck our pelvis indiscriminately throughout our yoga practice in order to create core stability is outdated and biomechanically incorrect.
In upcoming blog posts, I’ll offer more insight into our core as well as ways to make sure we’re turning on our deeper core for true stabilization. The more we understand our body and refine how we move, the more overall mindfulness we’ll cultivate both on and off the yoga mat. As always, if you have any questions or comments, feel free to let me know!
Related Online Workshop: Anatomy of the Spine for Increased Core Connection