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Core strength: Embrace the wobble

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At one time, a strong core was associated with six-pack abs but an updated view is that there is much more to them. Having defined abdominals is an aesthetic consideration, while a strong core relates to functionality. 

Anatomically, the core is the body’s midsection, a three-dimensional space that includes the muscles of the front, sides, and back. One can further distinguish between the inner and outer core. The outer core consists of the more superficial muscles that surround the midsection of the torso, while the inner core comprises the deep internal muscles creating an inner cylinder framed by the pelvic floor, diaphragm, obliques and spinal muscles. 

Pick up any fitness or running magazine and you will likely come across an article about the core and how to strengthen it. A strong core is essential for all types of athletes.  It is key to generate force as in a golf swing or to throw a ball.  While for runners, a strong core provides proximal stability for the arms and legs to move efficiently to generate forward movement. Some degree of core strength is also needed to meet the demands of moving through everyday activities with ease and pain-free.  

So what exactly is a strong core?  A strong core should be responsive to the task at hand.  Simply walking or running requires the support of the core to a lesser degree than holding plank or picking up a heavy object.  The degree to which the muscles engage should be automatic, allowing your brain to assume its role in directing the firing of muscles as needed.  

Breathing plays a major role in core strength.  In particular, diaphragmatic breathing where the inhale expands inner core at 360o, in the front, sides and back of the body.  This expansion of the mid section creates a stabilizing air pocket known as intra-abdominal pressure (IAP) which supports the spine and stabilizes the core.  A once popular method of drawing the navel to spine, or sucking the belly is counter productive to our purposes.   

Its important to distinguish between stability and rigidity.  The core needs enough mobility to allow it to reflexively respond as the situation demands.  Picture slipping on ice and the need for the trunk and limbs to reflexively respond to maintaining the body upright.  A rigid trunk is less responsive and will more easily thump to the ground.  

It’s not enough to do one or two exercises to build a strong core, even if you do 1,000 crunches. A more effective approach is to add variability to your movement and challenge your core in different ways. Core training can include isolating and strengthening the muscles of the outer core (transversus abdominis, obliques and, back muscles) through repetition and isometric holds. But it is equally important to challenge and train the core to be strong, stable and resilient while the arms and legs move. This is known as active core stability and requires the inner core to turn on reflexively without having to think about it.  This can be done through a number of balancing poses and adding random movement of arms and legs to create instability and imitate a sense of falling.  The body will wobble, arms and legs will flail, intentionally throwing the body off balance to strengthen the reflexive response to hold the ground and not fall.   

Good and efficient movement requires the interaction of muscles and joints to move in a co-ordinated fashion.  For example, if you slip on ice and are about to fall, the movement pattern of crunches will not be too helpful. However, if you have challenged your balance and stability, requiring the body’s stabilizers to reflexively kick in, you stand a better chance of avoiding an injury.  This concept also helps us appreciate the relationship between core strength and athletic performance. For runners a strong, stable and reflexive core is crucial and pays big dividends to optimize athletic performance. 

Below are a few poses to challenge your core in different ways.  For greater detail on this topic and many others see the book Yoga for Runners by Christine Felstead.

Practice diaphragmatic breathing, expanding the inner core unit as you inhale. 


In quadruped position, breathe to expand the mid section and into the lower back.  Extend arm and opposite leg, holding trunk stable and continue the intentional breathing.


Stand with feet hip distance apart.  Raise arms overhead and bend to one side, letting rib cage shift to opposite side. Hips remain level.  

Standing with feet parallel, gradually lift one foot off the floor.  Be prepared for some wobbling as you try to remain balanced. For greater challenge, close your eyes.


From simple balance, move your arms and legs randomly, in all directions.  Start with smaller movements and make them bigger, aiming to ‘almost fall’ but remaining upright.  You will wobble – on purpose!

These exercises are included in the book Yoga for Runners by Christine Felstead. The book includes a comprehensive review of the body’s key joints and muscle groups related to running and general movement. Breathing and meditation are also examined as ways to enhance running.

If you enjoyed this article, check out Christine’s Creating an efficient running stride here.

Christine pioneered the yoga for runners concept in 2001. She teaches on-line yoga classes and workshops and offers YfR retreats. Felstead has produced two best-selling Yoga for Runners DVDs and a 6-episode educational series. The 2nd edition of her popular Yoga for Runners book was released in 2021.

For additional information, visit:
Christine Felstead’s Yoga for Runners

Get your copy of Yoga for Runners at:

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