One of the things people frequently overlook in their workouts is exercises that focus on the lower abs. Exercise for the upper abs is what we usually learn as "ab exercises," but for that lean six-pack look you'll also need to focus on the lower abs. Exercise routines for the lower abs are simple, and three of the main ones will be covered here.

The major way to exercise the lower abdominals rather than the upper abdominals is to draw the legs up instead of the chest and shoulders. For the beginner, or someone just starting to get in shape, it's easiest to lie down in a position you might use to do sit-ups. From this position, draw the knees into the chest without raising the shoulders; as you become stronger and more capable with this exercise, begin to lift the legs upward without bending the knees, and lower them more slowly.

After some time with this exercise, your lower abs will begin to become much stronger. To ramp things up a bit, start from the same situp position, and crunch yourself into a full pike - lifting the feet straight up and reaching upward with the hands to touch the toes. This is a significantly more intense lower-abs exercise, and you'll rapidly tire from it; don't try to do too many of them at once, until you build a little more endurance.

To take things up yet another notch, hang from a pullup bar and lift the legs from a relaxed position to straight out in front of you. This is dramatic and intense, and your lower abs exercise admirably with it; men may also want to use this opportunity to work the upper body with a few pullups as well, which will focus some extra work on the shoulders and upper back.

As always, consult with your doctor before beginning any exercise program, and expect to work hard for a few weeks before seeing results. But if you're looking for that rock-hard six-pack body, a little extra lower abs exercise goes a very long way indeed.