Updated: May 07, 2008

Frequency: 2 to 3 times per week
Repetitions: 8 to 12

A. Lie on your back with your legs bent and feet on the floor a comfortable distance from your butt. Place a rolled-up towel between your thighs and hold a three- to five-pound dumbbell between your hands. Use your abs to lift your legs, then extend your arms toward the ceiling.