This is an excerpt from Delavier's Sculpting Anatomy for Women by Frederic Delavier & Jean-Pierre Clemenceau.
SCULPT YOUR ABS
The core and abdominal muscles play an important role in the body's aesthetics. Getting a muscular and toned belly in a few months is possible with targeted exercises. Say good-bye to your love handles and belly!
The abdominal wall is made up of four muscles:
1. The rectus abdominis is usually called the abs.
2. The external oblique is located on either side of the rectus abdominis.
3. The internal oblique is located underneath the external oblique.
4. The transversus abdominis is located under the obliques.
Unlike other muscles where you want to develop some size, here the focus is on keeping the waist small by having well-defined muscles.
Muscles in a Slim Waist
The rectus abdominis does help contain the belly, but there are some less well-known muscles that make the waist as small as possible:
> Transversus abdominis acts just like a corset.
> Internal and external obliques, to a lesser degree, also help to refine the waist when they are toned but not too muscular.
ROLE OF THE ABDOMINAL MUSCLES
When talking about the abdominal muscles, the first thing that comes to mind is definitely looks: Well-defined abs are synonymous with a flat belly void of any extra fat. But Mother Nature did not give you abdominal muscles just to look nice. The abdominal wall fulfills vital functions for movement and health. There are six good reasons to take care of your abdominal wall:
1. Increase your athletic performance. The core plays a large role in all physical activities requiring rapid running or twisting of the torso (such as golf or tennis).
2. Protect your spine. In concert with the lumbar muscles, the abdominal muscles support the spine. Weak core and abdominal muscles and a large belly increase the risk of lumbar degeneration.
3. Reduce muscle tension. A few minutes of core and abs work before going to sleep will relax the lumbar muscles, allowing the spine to decompress from the pressure experienced during the day. No more waking up in the morning with back pain.
4. Improve digestive health. Core and abs work improves digestion of food, thereby preventing bloating and constipation.
5. Reduce risk factors for health conditions such as diabetes.
6. Maintain cardiovascular health. Working the core and abdominal muscles is an excellent cardiorespiratory workout, similar to running but without the trauma to the knees and the spine.
Unfortunately, the lower part of the abdominal muscles is much more difficult to strengthen than the upper part. It is possible to do bridges primarily using the strength of the upper abdominal muscles. However, the lower abdominal muscles play the most important role in protecting the spine and preventing bloating in the abdomen. And it is also this part that tends to accumulate fat most easily. A good training program should therefore work both the upper and lower parts of the abdominal muscles. You should know that exercises that involve raising the torso recruit mostly (but not exclusively) the upper part of the abdominal muscles. Exercises that involve lifting the pelvis target the lower part a little better.