The “core” is considered to be the corset of muscles and connective tissue that encircle and hold the spine in place.
If your core is stable, your spine remains upright while your body swivels around it. The muscles forming the core must be balanced to allow the spine to bear large loads.
If you concentrate on strengthening only one set of muscles within the core, you can destabilize your spine by pulling it out of alignment. Think of the spine as the central pole of a tent supported by muscular guy wires. If all of the wires are tensed equally, the rod stays straight. If you pull the wires closer to the pole – as you do when you pull in your stomach while trying to isolate the transversus abdominis, The pole buckles. So, too, can your spine if you overly focus on the deep abdominal muscles.
A core exercise program should emphasize all of the major muscles that girdle the spine, including but not just concentrating on the abs. The most important postural muscle ‘The Soaz’ is the muscle that is most overlooked and has the ability to twist and distort the spine if not supple. This muscle above all others needs to be flexible to allow the spine to be responsive to movement from the more superficial phasic muscles.