Having visibly appealing abs - the so-called "six-pack" - has almost nothing to do with training abs! The key to seeing your abs is low body fat. Someone with very muscular abs who has high body fat will not see any definition, and someone who has not trained their abs at all with low body fat will see plenty of definition. In order to see abs, most men have to reach at least 10% body fat or lower, while women must reach 14% or lower.

The abdominal muscle is a large slab of muscle. The shape of the six-pack is due to tendons that stretch across the muscle. You cannot change a tendon's size, position, or shape through training, so the shape of your six-pack will not change.

Abdominal muscles bulge in their relaxed state. The abdominal wall is pulled flat when it contracts. If you improperly train abs, either by training to add significant mass and/or by neglecting other supporting muscles, your abs will protrude. You can see this in certain sports, such as professional wrestling - certain athletes are so lean that you can see their six-pack, but their stomach protrudes as if they have a beer gut!

While it is possible to store fat internally (i.e. "beer gut") and still have little fat underneath the skin, this condition is more than likely due to overtraining the abdominal wall while neglecting supporting muscles.

The pelvic girdle is a group of internal muscles that support your internal organs. When you perform abdominal work, your internal organs can shift and change your center of gravity. This is most evident when someone is performing hanging leg or knee raises and begins swinging.

By engaging the pelvic girdle during abdominal training, you not only strengthen your center of balance, but force more tension on the abdominal wall. The pelvic girdle is tightened by clenching your insides - squeezing your rectum or performing the same action as cutting off the flow of urine.

This exercise is known as the Kegel, and men as well as women can perform these. By performing a Kegel during abdominal work, you ensure not only that the pelvic girdle is strengthened at the same time, but also that you are building a strong core or center of balance. A proper hanging knee raise or leg raise will result in no swinging whatsoever - the torso will remain still and movement will be only around the pelvic area and through the legs.