Emphasizes lower abdominal and hip flexor muscles. Hanging Leg Raises. Using hanging abdominal straps to support upper torso, raise your knees as far as possible toward your shoulders, imagine rolling your abdominals up like you would a carpet, hold and crunch ab muscles together for full contraction, then lower your knees to abdominal level and repeat. Emphasizes lower abdominals. Form is everything.
Quality is more important than quantity.
You should visualize the rib cage being drawn down and in towards the pelvis when performing abdominal Crunches. The key to washboard abs. Having strong abdominals is one thing, but being able to see them is another.