People often tell me in class that they want to strengthen their core –  in order to ‘protect’  the lower back, to tone and firm the whole tummy area (the dismaying middle age spread…), and for overall strength and fitness for everyday life tasks. 

This ‘core’ strength is often misunderstood as the front torso or abdominal area. In fact, a strong ‘core’ requires

1. Developing good breathing mechanics

2. Working on spine and rib cage mobility

3. Training whole trunk varied movement - moving in ALL the ways.

To help you to build your core strength with yoga, first it’s helpful to have a clear picture of the key muscles and how they work together. Having this understanding helps to build brain connection to your trunk, leading to better awareness and control in movement. The good news is that we work and challenge this core muscular team in so many yoga poses and movements. This is a helpful foundation for more loaded activity like using weights and some sports, for reducing niggling back stiffness and pain, and for feeling more capable for everyday life stuff like lifting and carrying. 

What is the core?

The muscles of the trunk can be divided into an ‘inner’ and ‘outer’ core. Of course, they all work together constantly as we move, so this is an artificial (and debated) distinction, which we are using here to help us understand a complex system. 

The ‘inner’ core muscles can be described as a cylinder of muscles of the lower trunk (abdominal cavity). See the picture of a fizzy drink can cylinder, with the diaphragm at the top, the pelvic floor muscles at the base, the multifidus muscles at the back along the spine, and the transversus abdominus wrapping around from spine at the back to the navel at the front front like a wide corset. Often the psoas muscle is also included as part of the inner core, wrapping around and holding it all together.

The ‘Inner Core’ Cylinder of Muscles

 Here is another representation of the inner core, including the Psoas muscle, a long strap of muscle running diagonally from the spine at the low ribs (T12/L5) at its top end reaching over the pelvis and and attaching to the head of the thigh bone. So, from back to front of the abdominal cavity and top to bottom, like a supporting guy rope.

The Role of Breathing in the Core  

A key thing to note is that the top of the ‘inner’ core cylinder of your abdominal cavity, is the diaphragm, which is your main breathing muscle. The diaphragm is a circular-ish dome of muscle, attaching all around your lower ribs and to your spine at the back. It contracts and expands outwards and downwards on the inhale (pulling air into your lungs), and relaxes and moves back up into a dome shape on the exhale ( as the air is pushed out of the lungs).  You could try holding your lower rib area, and see if you can visualise and feel that movement. This might be a bit counter intuitive! WQe tend to think expand up on the inhale and relax down on the exhale - but this is not what is happening with the mechanics of breathing.

How the Diaphragm moves on the inhale and exhale

All together the coordinating muscles of this ‘inner core’ cylinder expand and contract as we breathe.

• With every inhale the dome of the diaphragm contracts to widens and moves down, increasing pressure (intra abdominal pressure- IAP) in the abdominal cavity. This creates tone in the walls of the lower trunk abdominal cavity, and activates muscular support along the spine. In this way core stability and strength is a pressure system as the contraction of the diaphragm and some the intercostal muscles on the inhale , creates this pressurised container. This is why weightlifters inhale, brace, and hold the breath as they lift super heavy weights! 

• With every exhale, as the diaphragm relaxes and domes back up under the rib cage, muscles of the ‘inner core’- like the TVA ‘corseting’ muscles - contract and create tone or firming right around the trunk, supporting you 360 degrees around your body, making you strong on the exhale too. The pelvic floor contracts and lifts on the exhale, creating support and tone from the base. 

At rest, this firming or toning is really minimal as it isn’t required to be that active, so it’s hard to feel. You can more or less feel this core tensioning when you sneeze or cough and feel firming in your trunk. Or if you imagine lying on a sofa and a puppy is about to jump on you. That reflexive tensing is your core, a combo of inner and outer! 

We can practice this ‘core engaged’ feeling in movement and under more demand/load, and using breath awareness. Thus is different from artificially tensing the tummy as a way to try and ‘engage the core’. Doing that isn’t really helpful and just tenses the front abdominals rather than this whole 360 degrees front-back-sides trunk pressure system.

With good breathing, you are strong and supported on the inhale as the abdominal cavity pressurises (think of a full fizzy drink can which you can’t squeeze) and as you exhale slowly, the cylinder walls (think of your ‘corset’ muscle) contract concentrically (shorten) to maintain that support, and the pelvic floor engages (now you could crush the cash as its not pressurised). 

Muscles of the ‘outer’ core

The ‘outer’ core is all of the more outer layers of muscles which we use more in three dimensional dynamic movements, (when the trunk and spine isn’t just holding firm and straight-ish) – the layers of oblique muscles move us into sidebending and rotation, the rectus abdominus or ‘six pack’ along the front of the trunk move us into flexion or rounding forwards and rotation. (See below)

The Muscles of the Outer Core

(You could add other supporting muscles as part of the outer core – around the hips, gluteus maximus (buttock muscles), the quadratus lumborum along the lower back, to name a few.)

How to access your core strength

My definition of the core:

“a responsive, dynamic system of 360 degree coordinated muscular trunk support, facilitated by the breath rhythm”. *

When load (weight bearing) requirements increase (e.g. picking up a heavy box, or shifting from down dog to plank, lifting up into a headstand), the firming response in the trunk is designed to increase reflexively, on demand, with full breathing. So what feels like a weak core is often a matter of needing some training, done by good breathing mechanics, control through the spine and trunk, and challenging your body progressively with load, to be able to manage increasing effort without sending signals of weakness or pain. Yoga is great as part of this strength development!

To sum up simply

Your core is how your trunk creates enough support or ‘firmness’ in movement for you to have a wide range of movement options – both holding your trunk relatively straight and stable in order to move your limbs around, and also bending/rotating your trunk in various ways in dynamic movement.

There might be a broad idea that the ‘inner core’ works more for stability to hold the spine and trunk firm and still as the limbs move, and the outer core muscles create 3-D dynamic movement, like bending and turning etc, but it's probably more accurate to say that all movement involves complex muscular teamwork to differing degrees. Especially in complex, whole body movement, like the poses and transitions like we do in yoga.

This is a super simplified ‘useful to know’ guide to the core, so please do come back to me with any questions and comments. Have you found this info helpful?

Please leave a comment if you found this useful, I’d love to hear from you.

 I hope now you are excited and feel well prepared to try out some of the core yoga moves in my blog post, ‘Top Ways to Strengthen your Core with Yoga’,  coming up next. 

You could also sign up to my email here for regular ‘subscribers only’ free practice videos, which includes tips on strengthening your core.

Note:

* For a more complex sounding but widely accepted definition of the core:

“The core is a 3-dimensional space with muscular boundaries: diaphragm (superior), abdominal and oblique muscles (anterior-lateral), paraspinal and gluteal muscles (posterior), and pelvic floor and hip girdle (inferior).” (Anderson & Huxel Bliven, 2013)