1. Lie on your back and raise your legs and bend your knees they are bent at a 90 degree angle. Place a stability ball on your thighs and extend both arms up to hold the stability ball in place.
2. Extend your right arm and left leg down toward the floor while using your remaining arm and leg to hold the stability ball in place. Pause for 1 second at the bottom before raising your arm and leg again back to the start position. Repeat the movement using your left arm and rightleg.
3. Continue alternating sides for the allotted time. A good goal is 45 seconds. Modification: If your back begins to arch too much off the floor or you feel any pressure in your lower back, keep your knee bent and drop your foot to the floor instead of keeping the entire leg straight.