First of all, let me say that the only way to reveal your abs is to lose that layer of fat above your abdominal muscles. There is no such thing is "spot-reduction". That means you can't work the abdominals and expect to lose more fat from that area. Where we lose fat is determined by where you store most of your fat genetically. For most men, it is the abdominal region. Women have more problems in their legs and hips. The best way to reduce fat is to cut your calorie intake guadually and lift weights to preserve muscle. Now that that is out of the way, I will tell you the benefits for training this muscle group. It helps you stablize the body during heavy lifts, and enhances your six-pack after you have lost the fat. Many people who experience back problems have weak abdominals. A great way to reduce the pain you feel in your lower back is to train your abdominals. Your abs serve as a support for your trunk. Since the lower back region and the ab region are also antagonistic muscle groups, it is very important to maintain balance between the two muscle groups. I will also say that there are no clear cut guidelines for training your abs. Some people believe in high reps, others believe that you need to train abs like other muscles groups like low reps. All that really matters is that a high level of intensity is reached, therefore stimulating the muscle fibers. I basically use high reps, emphasizing control and quality of contraction.
1 set - Ab Machine (with weights) - 15-25 reps
1 set - Crunchers - as many as possible (currently 60-80 reps)
The reason there is not too many sets is because I feel the abs get plenty of indirect work on other lifts. Also the HIT philosophy recommends low set/high intensity workouts. The abs are just like every other muscle group, work them hard and infrequently and they will grow.
