Pain and the Inner Unit

A lot of pain in the body is caused by a lack of central generation of stabilization which is called the Inner Unit. The Inner Unit became a term describing the functional synergy between the transversus abdominis and posterior fibres of the internal obliques, pelvic floor muscles, multifidus and lumbar portions of the longissimus and iliocastalis.

To accomplish automatic reflex control of the Inner Unit requires specific isolation training to enhance sensory motor control. Once control has been established, activation of the Inner Unit must be programmed into all movement patterns commonly used by the host. Failure to condition the Inner Unit to a high level of specificity often results in spinal injury and pain due to instability.

A simple understanding of this is as follows;

The hamstrings can be phasic muscles, movement muscles, tonic muscles and posture muscles. A weakness of the abdominal wall will cause instability, so to stabilize the spine the brain will activate more of the hamstrings. It is very common to see people with hamstring dysfunction when the abdominal wall weakens. With no Inner Unit working the brain will recruit more hamstring activity causing hyperactivity in a stabilizing function and in muscle tone, which decreases blood circulation through the muscles. An increase in muscle tone of only 5-10% can decrease blood flow by 50-75%. This will starve the muscle of oxygen and nutrients and reduce the removal of waste which sets up an acidic environment resulting in muscle damage and pain. This is why a force – couple relationship of the Inner and Outer Units is extremely important in the maintenance of a pain free body.