The “core” from an exercise perspective, refers to the muscles that move and stabilize the trunk.  Most people know that abdominal and low back muscles are core muscles, but what exactly is the core?  The core is our center of balance, and all the muscles that connect to or cross the joints of the spine and pelvis. Besides the abdominals and low back muscles, the gluteal muscles, the pelvic floor muscles and most of the upper thigh muscles make up the core.
 
The most familiar core muscle is the outer abdominal muscle known as the “six-pack” – the rectus abdominis. Actually, the rectus abdominis is an “eight-pack”, but typically you don’t see the bottom two compartments of this muscle that stretches vertically from the bottom of the rib cage to the pubic bone. This muscle enables you to bend forward. Underneath the rectus abdominis are the external and internal obliques, the external criss-crossing above the internal.   The external obliques extend diagonally from the ribs to the front of the pelvis. The internal obliques extend diagonally in the opposite direction underneath the external obliques. There is a pair on each side of your torso. Together, these muscles rotate your torso and bend it sideways.  They are also one of the main stabilizers of the trunk. The innermost abdominal muscle the tranverse abdominis. The transverse abdominis runs horizontally from the sides of your rectus abdominis around your back to the bottom of the ribs and pelvis.  It holds in the contents of the abdomen (i.e. your organs) and is a main stabilizer of the trunk. 

Equal in importance to the abdominals are the low back muscles. They consist of the erector spinae muscle group that runs vertically down your spine to the pelvis. They bend you backwards and help stabilize the spine. The quadratus lumborum muscles run on either side of your lumbar (lower) spine from the bottom of your ribcage to the top of the pelvis. They stabilize your spine and play a large part in bending sideways. It would be difficult to walk without these muscles working well. Other important core muscles are the gluteus maximus, gluteus medius, and gluteus minimus. They help stabilize the pelvis, and move the leg to the back and side.  Finally,  the upper thigh muscles that cross the pelvis, mainly the rectus femoris in the front of the thigh and the 3 hamstring muscles in the back of the thigh  help to stabilize the your hips and back.

Because all these muscles work together to keep your spine aligned, it is critical to exercise and stretch them. Doing so will help prevent pain and injury to the back. Think of popsicle sticks all tied together with rubber bands. If those rubber bands are thin and loose, the popsicle sticks will flop out of place. Conversely, if the rubber bands are too tight, the popsicle sticks will bunch up and pinch each other. In the human body, this means pain and/or injury. It is necessary to both strength train and stretch the muscles of the core to keep them strong and flexible and eliminate a lot of the pain and problems you have in the back.

Many people think that doing daily crunches will keep their core in shape, but it takes a variety of exercises and stretches for all of the muscles to keep the core strong and flexible. It is well worth the investment in a couple of sessions with a fitness professional if you are in doubt of what exercises to do to keep your core in shape. Health care costs of maintaining a strong core are far less than the cost of chronic back pain and injury. Keeping a strong core will allow you to stand up straight and face your day!     

By Mary Miriani. BA Exercise Science; ACSM Health/Fitness Specialist.
Reality Fitness, Inc.; Naperville, IL. Contact her via email, mary@miriani.com.