Do you have disc herniations or sciatica?

Lay face down on a table with your hips hanging off of the end. Extend one leg up as high as you can. When you lift higher, you activate your lowest erector spinae, which likely needs some strengthening. When these muscles contract, they hold your spine in a more extended position, thus keeping pressure off of your discs. Feel free to take the leg up as high as you can. Repeat on the other side.