What physical exercises should be done for persons having sciatica problems?

Cardiovascular: Sciatica refers to lumbar spine related leg pain. In general, cardiovascular or aerobic activity including walking can be helpful in treating -if the walking can be tolerated- and possibly preventing sciatica. Mckenzie or direction-bias exercise may be helpful but must be learned from a specially-trained physical therapist.

Core Exercises: Typically core strengthening exercises are the best to help relieve pressure and forces in the spine. I would try and google some or look them up on youtube to see descriptions. If you can do them yourself, wonderful otherwise ask your doctor to get a referral to a good physical therapist for further assistance.