Core work: Leg Lifts–because pure strength doesn’t help back pain… endurance does!

Studies have shown that endurance training for the core and back has better results than strength training. So lower the weight on these core machines, do exercises more slowly, and be very careful with what you’re doing to your back.
Or just go the supersafe way and use exercises like the one in the video.

But if you really are in acute pain, even that might be too much. In that case, just do simple movements that are not exhausting at all. Just mobilize! Read Paul Ingraham’s manual on Mobilizing!