To do this exercise you will need a mat. Start by lying on your back with your knees bent and your feet planted in the floor. Your hands should be clasped behind your head to offer support. To begin the movement, inhale into the back of your ribs and then exhale as you press the ribcage into the ground to lift your head neck and shoulders. Then continue the exhale as you lift the head neck and shoulders slightly higher and then release just a bit and then repeat in a quick repetitive motion until you are positive every ounce of air has left your lungs. Then inhale into the back of your ribs to release the head, neck and shoulders to the ground. Repeat 5-6 times.
Things to think about
As with the abdominal curls this is an exercise that is more complicated than one might think just looking at it. Once again if you have a diagnosis of Osteoporosis of the spine this is not the exercise for you because the risk of vertebral fracture is increased when the spine is in flexion.
As you are doing these pulses be sure that you are continuing to exhale and that you inhale to return to the ground. This will guarantee that the abdominals are in the most efficient place to work.
Also be aware that you are not transferring between flexion and extension of the spine, you are moving between flexion and more flexion during the pulses. The abdominals are engage the entire time that your body is pulsing.