There are 4 layers of abdominal muscles, each with fibers running in different directions. The crisscrossing pattern shapes your midsection and supports your lower back. The top layer is called the rectus abdominal. It is actually 2 columns of muscle with 4 little squares on each side. We often refer to these muscles as the 'six pack' (there's actually 8 packs). The second and third layer are called the internal and external obliques. Those muscles lie more to the sides of your midsection. The deepest layer is called the transverse abdominus. This is the only layer of abdominal muscle that actually spans all of your mid section. It is THE muscle responsible to flattening your belly, supporting your lower back and assisting your disphragm. Unfortunately, most people do 'crunches' to try to strengthen their abs but because of the way the transverse muscle is constructed, crunches don't cause this muscle to contract or strengthen. To tone and strengthen your mid section, you must strengthen your transverse muscle. The best way to strengthen this muscle is to use your breath and your brain. The only way to get the transverse to contract and strengthen is through concentrated exhalation - bascially, as if you were blowing air through a straw. Blowing up balloons is a wonderful transverse strengthener.
All 4 layers of abdominal muscle are really thin compared to other muscles. So how you strengthen them is easy - you contract them as deeply as possible and you hold the contraction. Toning and strengthening the transverse can take up to 2 inches off your midsection measurement.
Try this exercise. It can really be done anywhere and anytime and no one has to know you are doing it.
1. Take a deep breath. Pull the oxygen all the way to the bottom of your rib cage. You should feel your rib cage expand as your lungs fill with air.
2. As you begin to exhale, exhale as if you were blowing air through a straw. At the same time, pull your belly button towards your back. See if you can feel the bottom edge of your rib cage pull in and decrease in diameter.
3. Hold your abdominals in as tightly as you can while slowly counting to 10. Make sure not to hold your breath. Although you won't be able to breath deeply when holding in the abs, you can take little breaths. You could hold your breath for 10 seconds at a time without consequence UNLESS you have high blood pressure or tend to get headaches. Holding the breath tends to push pressure into chest and head so try to take little breaths throughout the 10 seconds.
4. Relax and repeat often throughout the day.