This rolling move strengthens and tones your abs and your lower back.
-Plank Pike-Up: Take an exercise ball and lie on top of it with your shins on the ball and your palms on the floor under your shoulders. Now, use your abs and legs to roll the ball to the middle, lifting your hips and keeping your head down between your arms. Your body should be in an inverted V-shape. Hold here for 1 count, then roll back to the start. You'll do 10 to 12 reps. Be sure to pull your abs in and keep your head even with your spine as you move in and out of the V. This move works your abs and your lower back.