Now, I'll be the first to tell you that you
can't totally isolate the lower abs.

However, what you CAN do is use certain exercises,
body positions and equipment to help shift MORE of the
tension to the lower abs over the rest of the rectus abdominus
(the six-pack abs).

Targeting this area will help develop that nice "V" taper
that you see in the lower abdominal area when bodyfat
levels start getting low enough to see it.

It can also help tighten up that section of muscle, which
when done along with other targeted rotational exercises,
can flatten the stomach.

The exercise I've got for you to HIT that area strongly is
one I call the See-Saw Leg Raise.

It IS a leg raise movement, but with some cool modifications
that take pressure off the lower back and add serious
tension to the lower abs.

This one is awesome...

Nick Nilsson
The "Mad Scientist of Muscle"