First, consider the abdomen as only part of the core. Your core musculature extends into your pelvis and hips. Think of it as your center of gravity, the place where your upper body connects to your lower body. A system that essentially, allows you to accelerate, decelerate, transfer and resist forces throughout your body. Why should you worry about these stabilizing muscles, if you want to have a flat stomach?
Your core stabilizes your spine to allow movement of your legs and arms. Without proper stabilization there is a decrease of efficient movement. If there is a decrease in any movement pattern, compensation must occur leaving you open to a higher rate of injury. Most of us think of a “strong abdomen” or core as having a “six-pack.” However, the primary function of the rectus abdominus (six-pack) is flexion (bending forward) of the trunk (upper body). The external obliques run along your ribs and attach to your pelvis, allowing you to bend
and twist. Although these two groups of muscles allow movement about the spine, they do not stabilize the spine.
For example, doing sit-ups and leg lifts without a strong core will create a compensation of the iliopsoas musculature to provide most of the work in flexing the trunk. The iliopsoas is a muscle group that originates in the lumbar spine and attaches to the femur (thigh). If this muscle becomes over developed it could have an adverse effect on your low back, creating lordosis (arch) in your low back. Excessive lordosis is generally a lack of control in the pelvis, which can develop into low back pain.
Some of the major core musculature, the transverse abdominus, internal oblique, multifidi and pelvic floor muscles surround the spine to provide stability. Think of it as your internal safety belt, when strapped in, it protects your spine from numerous forces.
Activating the core muscles, or bracing your mid-section, if never done before requires some practice. One of the best methods to activate this muscle is to “cough” or “suck in your bellybutton.” Start by performing a pelvic tilt. While lying on the ground with your knees bent and feet flat on the floor, tilt your pelvis so that your back flattens against the floor. Brace your mid-section by sucking in your bellybutton or coughing to activate the deep transverse abdominus. Next, activate your pelvic floor muscles much like you are stopping yourself from going to the bathroom, hold for a count of 10, relax and repeat for 5 repetitions. Make sure to keep breathing while performing this exercise.