This is a great way to increase the stability of your lower back.

1. Lie with your stomach over a therapeutic ball while stabilizing yourself with your feet and arms and keep your head in line with your body.
2. Tighten your abdominal muscles to flatten the spine by pulling your belly button towards your back and hold the contraction throughout the exercise.
3. Bend one knee and lift it up towards the ceiling.
4. Lower the leg and repeat on the other side.