How to Do Crunches So They Actually Work Your Abs

This move challenges both your lower and upper abs to maintain torso stability while your arms and legs move away from your center. If you don't have a dumbbell, you can do this move with just bodyweight, too.

• Lie on your back with your arms reaching toward the ceiling, holding one weight with both hands. Bring your toes toward the ceiling, keeping your knees straight. This is your starting position.
• Lower your right leg toward the floor, keeping your lower back touching the mat.
• Lift your leg to return to the starting position. Repeat on the opposite side. That's one rep.