Reverse crunches are one of the top exercises to build a deep V-cut and defined LOWER ABS. Stick your hands behind your head, tighten your core, and powerfully contract your lower abs — lift your hips off the ground and pull them into your chest. Do a few sets of 20 reps and you'll build muscle in your lower stomach in no-time flat.
The Waist-Slimming, Lower Ab Workout
Best Tummy Workout? looks like it could be painful, anyway!