The Frog

What it does: Strengthens the upper back, shoulders, buttocks, thighs, and calves.

How to do it: With your belly on the ball and your feet in a squat (frog) position, press into the ball with your knees and abs. Roll your shoulders back and open your chest. Reach back and down with both hands, arms straight. Release and lie over the ball, pushing into another of the dynamic push-up.