The core needs to be strong for a person to function optimally. The core can be viewed a couple of different ways,- the core can be said to be the muscles in the center of our body that must activate before the body moves in order to keep us safe and stable and balanced. Or one could say that all efficient movement patterns begin or travel thru the center of the body, so that the core muscles can counter the forces of the arms, legs, and spine, again to keep us safe and strong.
Where is the core, and how do we use it? Mistakenly, too many persons believe that core = abs. While the abs are part of the core, they are not its entirety. The diaphragm or the breathing muscle is part of the core, and research shows it may actually be the leader of the pack. The small deep muscles in the spine, called the multifuda, help stabilize in the back. And the pelvic floor, known as kegels, is actually part of the core. If you lift heavy objects without those pelvic muscles activating, you may find that either bladder leakage occurs or that a hernia has formed, so indeed these pelvic muscles are a critical part of the core. The core muscles move in toward the center of the body and upward to counter gravity when they are working efficiently. And if we want the most bang for the buck, activating the core on the exhalation works best. If you actually grow taller when you activate the trunk, there is a greater chance you are using the muscles correctly. If you get shorter, or tend to crunch up a little, you are probably using the sit-up muscle, which is not a core muscle. The sit-up muscle is a mover, not a stabilizer, so it is not part of the core. How can you touch the abdomen and know which ones you are using? Place one hand above the navel and one hand below. Tighten the abs; under which hand are the muscles tightening first or most? If it is under the top hand, chances are you are using the sit-up muscle. If it is under the bottom hand, you have probably found the core ab muscle, especially if it feels like a horizontal band of tone across the lower abdomen which lifts the abdomen in and up.
Sometimes the definition of the core is extended to mean any muscle of the trunk which stabilizes, so shoulder blade muscles can be considered core, because they need to turn on before the arm moves, especially if doing a task which requires force (pulling on a heavy door).
Poor posture, scar tissue, tight muscles (like hamstrings or the psoas), or poor technique when trying to strengthen the core are factors which hinder effective core activation. We can identify and address these or other factors which are preventing you from becoming strong and pain-free.