Which Ab Move Works Best?

The Pilates roll-up is 30 percent more effective than the standard crunch when it comes to targeting the rectus abdominis (the "six-pack" muscle), say researchers at Auburn University in Montgomery, Alabama. Because the move challenges your abs through a fuller range of motion, it recruits more muscle fibers.

Try it:

Pilates Roll-Up

• Lie back with legs straight and arms extended above head next to ears.
• Bring arms forward, tilt chin down, and slowly curl upper body up, reaching hands to toes.
• Repeat 8 to 10 times three times a week.

Originally published in Fitness magazine, October 2005.