Lying facedown, place one hand on top of the other under your forehead. Bend your knees, turn your toes and knees outward, and place your heels together, flexing your feet. Pull your abs up and in, and draw your tailbone down, keeping your hips in contact with the ground to protect your back. Inhale, contract your abs and buttocks, then exhale as you lift your thighs and knees off the ground; pulse your feet upward 5 times to complete 1 rep. Inhale, lowering your thighs to the ground; exhale to finish. Do 8 reps.