This Review Originally Appeared in "Exercise The Best Of Abdominals" written by Andy Troy

The human body is an amazing machine. It is a complex collection of moving parts carefully designed to get us where we want to go. It consists of 206 bones and over 600 muscles working together as one. At the core of this miracle of engineering are the abdominals.

The abdominal muscles, or abs as they're often called, work together with their neighboring muscle groups to hold ic all together. They are the sole source of stability for the abdomen — a region of the body where no bones are present. In addition, they create or control a variety of movements taking our torso in an assortment of different directions.

The abdominals consist of several layers of muscle with fibers running in a number of different directions. The most superficial, or closest to the body’s surface, is the vectus abdominis, which means “straight abdominal.” ‘The rectus is a narrow, flat muscle and is also the muscle most visible to us. It is the one often referred to as a “six pack” — referring cto its cube-like appearance, which is actually the result of three tendons that cross the rectus’ vertical fibers.

This muscle has several key functions, most importantly spinal flexion. Any time you bend forward from the waist, whether you're doing a crunch or just getting off the couch, your rectus is a prime mover for that movement. It also assists in lateral flexion, which leans the corse to the side from a neutral spine position and, helps raise your torso back to neutral. Your rectus, along with your other spinal flexors, is crucial in maintaining a healthy back. In addition to offering support, each time your abdominals contract, your lower back muscles are effectively stretched.

Next we have the external obliques, a muscle on each side of the torso whose fibers angle downward diagonally and wrap around the side of your trunk. Not only is it a prime mover in pure spinal flexion, but also in both lateral flexion and rotation of your torso to the opposite side.

Beneath them lie the internal obliques. They attach in almost the same place, but their fibers run up instead of down, then wrap around the front of your trunk. This muscle also is a prime mover for spinal and lateral flexion and rotation to the same side. In essence, when rotating your torso, your internal and external obliques counterbalance each other, thereby improving stability. When both contract they compress the abdominal cavity to properly stabilize the region.

A good way to visualize these two muscles is to picture yourself wearing a pair of pants with both front and back pockets. Now picture the angled fibers of the external obliques running from your sides across your body into the front pockets while the internal obliques do the same thing into the back pockets of your pants.

When training the obliques there is one concern worth noting. People often labor under the misconception that by excessive resistance training through crunk rotation (broomstick twists, Nautilus machine) or lateral flexion (side bends with a dumbbell in your hand) you can specifically target the fat deposits that have developed along the sides of your waist (love handles) for reduction. This process is called spot reduction and is a physiological impossibility. You cannot target specific concentrations of bodyfat through a specific exercise.

The good news, however, is that exercise will help you reduce fat deposits by creating a calorie deficit. If you take in less calories than you burn, your body will draw on its fat stores to meet the demand.

An ab muscle we don’t often hear about is the guadratus lumborum, a square muscle that runs from the lower border of the ribcage to the upper border of the hip. However, its proper development is crucial to the health of your back. Its main func- tion is as a prime mover in lateral flexion. When it’s underdeveloped or inflexible it can contribute to lower back pain by pulling your hips out of alignment.

Finally there is the transverse abdominis — the deepest layer of abdominal muscle. Its horizontal fibers ring your abdomen, pro- viding belt-like support.

There are no specific movement patterns to develop this muscle since it's not directly involved in joint motion. But placing your body in an unstable environment, like exercising on a stability ball, forces this core muscle to “kick-in” and stabilize che movement.

There are other muscles that are not part of your abdominals, but because of their relationship to them, they are worth mentioning. They include the following:

Erector spinae: The primary muscle involved in lower back extension, its most important role is that of stability. Good posture, which holds you upright against the force of gravity, is effective in developing this muscle.

Ilipsoas: These are the primary hip flexors. Most people don't need to develop them, since a sedentary lifestyle often leaves them overdeveloped and tight, thereby putting pressure on the lower back. Stretching them, is therefore, important. This can be done through hip extension.

Multifitus: This muscle is a prime mover in back extension, as well as rotation of your spine to the opposite side. In addition, it serves as an important stabilizer during all functional movements.

While there are a variety of ways to effectively train your abdominal muscles, there are certain rules worth following in order to maximize the benefits and reduce the risk of injury. Below are several do’s and don'ts that will help you to get the most from this portion of your exercise routine.

Do abs last: The rest of your body counts on your abdominal muscles for support. Once you fatigue your abs by working them effectively, they will be less able to offer support. As a result, abdominal work is best done at the end of your routine.

Don’t neglect the core: While they lack the visual appeal of the rectus abdominis, your core abdominals are crucial to the integrity of all your movements. Remember to train them, using exercises like the plank.

Do vary your movement speed: Variety is the spice of life, and a key to effective abdominal training. Doing the same exact routine month after month will cause your body to adapt, minimizing benefit. Rotate your routines — it will help your body and your mind.

Don't ignore the isometric component: It is important to keep in mind that the lack of movement, in the presence of resistance, is a key to effectively developing any muscle group.

Do control the points of movement: Limiting motion to specific joints is a key performance of any exercise. Movement elsewhere shifts the load to places where it was never intended to be. This not only minimizes gains, but to the proper given increases the risk of injury.

Don't pull on your head: Make sure not to pull on your head to raise your upper body. This will take pressure off your abs where it belongs, and places it on your biceps. It can also stress your neck muscles and spinal joints. Always remember when doing crunches, you are doing abs, not arms. Crossing your hands over your chest might help avoid cheating.

Follow these rules to get your abs into shape — the right way.