Here is a link to a list of simple and generally safe ab and core toning exercises that do not involve crunches or sit ups. The goal is to increase your ab and core strength without irritating your back or sciatic nerve. If you already have a pain or injury do not do these without talking to us or your health care professional to determine the problem/diagnosis first, Then you can get on with treatment or better exercises for you.
With that being said take a look at this link below and see if the 6 exercises fit into an overall core and muscle building program for you.
6 Moves For Strong, Toned Abs