The first region is the Transversus Abdominus, which wraps around your torso and plays a major role in your posture. The second region is the Internal Obliques, that are on the sides of the torso. The obliques are worked when rotating the torso. The third group is the Exernal Obliques, which are also located on the outside of the torso, and are also worked when rotating the torso. And finally, the fourth region is the Rectus Abdominus, which stretches from the bottom of the ribcage and down to the pelvis. The Rectus Abdominus is comprised of two parallel muscles and are separated by a band of connective tissue. The Rectus Abdominus region is what is commonly referred to as a, "six pack." Now, lets take a look at exercises that target each specific region.

The Transverse Abdominus is often ignored, because many common exercises do not place heavy emphasis on the trunk. An excellent exercise the work the Transverse Abdominus is the side leg raise, and side bend. To perform a side leg raise, lay on your right side, with your elbow underneath your right shoulder, with your weight on the outside of your right foot and your right arm. Lift your body so that it is in a straight line. If performed properly, you will feel the action in your trunk as you left your hips the ground. An advanced version of this exercise involves holding the position for a period of time, before lowering your hips back to the floor.

The obliques can be targeted with many of the same exercises as the Transverse Abdominus. However, one exercise that is an exceptional obliques-targeting workout is the lying crossover stretch. To perform this exercise, lie on your back with your arms straight out from your sides (perpendicular to your body, for support). Lift one leg straight up, then lower it to the opposite side. For example, lift your right leg straight up, then lower it to the left side, crossing over your left leg, then hold and stretch. Alternate legs and repeat.

The Rectus Abdominus can be targeted with various crunch and leg lift exercises, but one of the most popular and highly recommended workouts is the bicycle exercise. To perform this exercise, lie on the floor with your hands behind your head, bring both knees to your chest, lift your shoulders slightly off the ground. Then, extend your right leg to where it is at a 40-45 degree angle with the floor, while rotating your upper body to the left, bringing the right elbow towards the left knee- Alternate and repeat.