Nikolai Bogduk and Lance Twomey published Clinical Anatomy of the Lumbar Spine in 1987. They were the first to introduce clinical observations of the abdominal and back muscles coordinating as a “functional unit.”
WHAT Is THE OUTER UNIT
In 1999, Australian scientists C. Richardson, G. Jull, P. Hodges, and J. Hides published Therapeutic Exercise for Spinal Segmental Stabilization in Low Back Pain. Within, they first coined the term inner unit, describing how the deep abdominal wall works synergistically with the outer unit – the conventional targets of fitness: rectus abdominus, obliquus externus abdominis, and psoas.
WHAT Is THE INNER UNIT?
Paul Chek explains the inner unit as “describing the functional synergy between the transversus abdominis and posterior fibers of the obliquus internus abdominis, pelvic floor muscles, multifidus and lumbar portions of the longisssimus and iliocostalis, as well as the diaphragm.” (“The Inner Unit: A New Frontier In Abdominal Training,” IAAF Technical Quarterly; New Studies in Athletics, April 1999.)
We can consider the inner unit to be the myofascia stabilizing and protecting our internal architecture, but also the bridge to controlling breathing and, as a result, our autonomic nervous system. The correct firing of the inner unit and its effective recruitment not only affects our spinal stabilization so that our prime movers can get in there and get the job done, but it also affects our ability to breath and move.
Breath links both aspects of the nervous system: autonomic and voluntary. When a particular local site manifests an issue, moving through it, around it, or with it may cause breath holding and bracing – an involuntary protective fear reflex to keep the injured area from further trauma.
This bracing serves no purpose in healing. It can only serve to reinforce the potential for ongoing problems in the local site and reinforce the chain of density, tension, or injury by forcefully maintaining the body’s focus on the local site. This is why “power breathing” and “high tension” techniques may be able to increase tension locally and globally for the short term but only result in eventual injury. This is additionally why powerlifters (whether recreational or competitive, with bodyweight or weighted equipment) are, if not immediately then eventually, riddled with aches, pains, injuries, and structure dysfunctions.
Because voluntary exhalation is a relaxation trigger for the entire system, exhaling through a discovered local tension can cause the tissue to relax. Therefore, we must use active exhalation through perceived effort, discomfort, or fear to release the local issue so that the structure can reorganize in its innate, normal, pain-free form.