12. Reverse Crunch:

- Lie down on the floor mat by placing your hands on the floor. You can also put them behind the head.
- Slowly bring the knees to the chest for 90 degrees. You can keep your feet together or crossed.
- Pull your abs and take off the hips above the floor till the legs are to the upwards direction.
- Come back to the normal position. You can do this 1-3 sets of 12-16 reps.
- Let the abs lift your hips. Don’t swing the legs.
The reverse crunch is the 7th best ab exercises that strengthen rectus abdominis.
Courtesy: http://www.stylecraze.com/articles/womens-exercises-for-abs/