A tight core is about more than a flat stomach or washboard abs. The core muscles move, support, and stabilize your spine. Your obliques, abs, and three long muscles that run down your back from your shoulders to your pelvis are what make it possible for you to bend forward and backward, move side to side, and twist your body.
Strong core muscles are important for balance, and working your core could play a part in reducing stress. People who suffer chronic back pain often find that a core strengthening regimen provides a lot of relief.
In the video above, L.A.-based trainer Julie Diamond leads The Fine Line founder Sue Cowie through a simple core workout that includes leg lifts and bicycle crunches.
In the video below, they take a more advanced approach to building ab strength: push-ups — including a one-legged variation.