What is it?

The Intrinsic Core, also known as the Intrinsic Stabilitzation Subsystem (ISS) is comprised of 4 muscles: the diaphragm, transversus abdominis,  multifidus, and pelvic floor. You can see from the photo below that these four muscles form the shape of an internal cylinder.  It is the first subsystem formed in our neurodevelopmental patterning.

“If the intrinsic core of your body is unstable, the nervous system inherently restricts mobility to obtain the necessary stabilization. It locks down joints in a primal attempt at stabilization.” – Dr. Perry Nickelston (1)

Intrinsic Core; Photo Courtesy of Brent Brookbush

The Intrinsic Core; Photo Courtesy of Brent Brookbush

Function of the Intrinsic Core

The 4 muscles of the intrinsic core allow us to create intra-abdominal pressure and spinal stability. This stabilization enhances the transfer of force between upper and lower extremities and all other subsystems. (2)

The other four subsystems are :

  • Anterior Oblique Subsystem (AOS)
  • Posterior Oblique Subsystem (POS)
  • Lateral Subsystem (LS)
  • Deep Longitudinal Subsystem (DLS)

Breathing and the role of the diaphragm

“If you don’t own your breath, you don’t own movement.” – Karel Lewit

There are two types of breathing styles we can use.

  • Anatomical Breathing – The body is compressed as air gets squeezed out of you and expands as you take air in. This is how we should normally breathe when we are taking a diaphragmatic breath. Anatomical breathing is also useful during stretching and mobility. (3)
  • Biomechanical Breathing – When your body gets compressed you inhale to produce intra-abdominal pressure and  expand during forced exhalation (3). Biomechanical breathing helps create stability in the intrinsic core and is the type of breathing used during hardstyle kettlebell swings, deadlifts and other lifts. It is at the heart of all our training and practice.

Rowing Applications

First, if you are experiencing any breathing dysfunctions watch the video above and perform the Diaphragm RAIL. Practice crocodile breathing or use a prop to emphasize proper diaphragmatic breathing.

Once you are breathing from your diaphragm subconsciously you can begin to practice and integrate it into your rowing.

Give this a try:

  • During your next erg session try inhaling right before the catch to create a bubble of intra-abdominal pressure. This will help transfer force across your body and you should see a drop in your splits.
  • Play around with the timing of the breathing and see what effect this has on posture and power.

Next week’s episode will cover the hip hinge and tie in the biomechanical breathing match. Leave your comments below and use the share buttons on the right to post to your favorite social media network.


  1. Nickelston, Dr. Perry. Primal Movement Chains: Moving Beyond Mobility Manual.2015. Print.
  2. Brookbush, Dr. Brent. Intrinsic Stabilization Subsystem Integration. BrentBrookbush.com. Website.
  3. Jones, Brett. Cook, Gray. O’Connor, Jeff. Kettlebells from the Center: Dynami. Manual. 2010. Print.