First - if you don't know what the transverse abdominus (TVA) is - consider yourself fortunate - sometimes ignorance is bliss! ;)
The much talked about and emphasized TVA is one of your abdominal muscles and according to research is the first muscle in your body to fire to stabilize you for movement or even for lifting your arm from a chair. It is thought to be the prime muscle in the body for spinal stability.
The TVA is designed like a corset - the fibers run in a straight line around the body connecting to the fascia in the back - since it has this design the popular explanation of it's function is that it draws in to produce stability.
I have a different take on this.
The TVA is like a retaining wall for intra-abdominal pressure (IAP). That is right a retaining wall designed to hold in the pressure necessary to stabilize the spine. Proper IAP is the combination of the pelvic floor muscles (more on this on another blog), the back, the abdominals (including the TVA) and the _____________??? Do you know? and the diaphragm. That's right the parachute shaped muscle that separates the chest cavity from the abdominal cavity and helps you breath. It forms the top of the box and when you inhale properly and the diaphragm expands and pushes down into the abdomen - the TVA must perform it's retaining wall function and contain the pressure with the pelvic floor and the rest of the "box".
If the TVA doesn't do it's job and the pressure cannot be contained - low IAP and low spinal stability. Drawing in will actually decrease the effectiveness of the "box" and prevent the diaphragm from expanding and allowing the TVA to perform it's retaining wall function.
Pull-up the pelvic floor (become familiar with squatting and kegel exercises if you don't know how to do this) and make the abs flat and solid - not pulled in - and use the diaphragm to expand down against the retaining wall - as the TVA tightens to hold in the pressure it will pull on the thoracolumbar fascia and viola - IAP and the opportunity for a stable spine.
Start thinking of the TVA and IAP in this manner and reap the benefits of a stable spine and proper abdominal activation. And tune in tomorrow for a simple "core" activation "trick".