The Outer Unit

The Outer Unit – what is it and how does it help us move better?

When I went on my first Master Instructor training, I was introduced to the concept of how “groups” of muscles assist the core.  These groups help provide dynamic stabilisation (support in moving spinal exercises, Pilates exercises and every day life).  Plus, also providing Lumbopelvic stability, which is the ability to completely stabilise the pelvis in neutral.  My mind was blown and a whole new world of understanding was opened.

There are four groups of muscles in the outer unit: Deep Longitudinal System; Anterior Oblique Sling System; Posterior Oblique Sling System; and Lateral System.

The four systems work together to provide balanced three-dimensional movement and integrate the whole body to move as one. They work as a team to balance out movements of the spine or support of the spine. This month we’re going to focus on the Deep Longitudinal System and the Posterior Oblique Sling System.  As they definitely function together, but not in isolation to the other two.

Deep Longitudinal System

This group runs from the back of your skull, down your spine and splits at the buttocks.  In continues down the back of the legs and ends up on the sole of your foot.  Imagine that its two columns of support along the whole back body.

Posterior Oblique Sling System

This group runs from just under your shoulder-blade, across to the opposite buttock area.  Imagine it’s a band or sash running from one side of your back to the other.

When would you use the system in a Pilates Class?

When we start a class, we normally start in standing, so I can assess your alignment. The Deep Longitudinal System is key to help with an upright posture. Sometimes I might ask you to put your hand behind your head whilst standing. This is to activate this system.

As this system runs down the whole of your back body, then obviously any of the Swan series we do (extension), then this system is a key contributor to this action.  Also, your Posterior Oblique Sling would be helping in the action too.  In this case, both sides of each system would be working at the same time – so what happens if only one side is active?

When only one side of these systems is working, it will produce either side bending (lateral flexion) or twisting (rotation).  We have a lot of movements that have these movement patterns, predominantly in seated.  Think Seated Side Stretch, Saw and Spine Twist – these systems are instrumental to these movement patterns. 

This is why sometimes you feel less movement in one direction that the other.  One of these systems could be more dominant than the other. 

I hope you enjoyed my anatomy geek section.  Next time I’ll talk about the other two systems and how they relate to each other.