Lower back (and back/spine problems run the gamut) can be very tricky. What I've learned is that doing any excercises with lower back issues is that it can depend on the stage you are in your healing process. Your back has to be ready for it and you have to consider that many excercise sitesor demonstators even back doctor have not necessarily everhad back pain.
Most of the renamed calesthenic excercises like "Seal Stretch" (cobra/Bhujangasana) or HURDLER'S STRETCH(Janu Sirsasana or Head-to-Knee Pose or single leg stretch)..areyoga postures.
If you have lower back issues for example you really have to be carefull how you do Cobra..aka "Seal".. because of the compression factor involved on the lower back. There is a slow, and wiggling or shifting way to move into that pose."Baby Cobra" or just stretching forward and up slighty feeling the lengthing in the waist/spine...more than focusing on going higher,may seem boring but it can be more helpful for severe cases or prevent flare-ups. The danger in doing someexcercisescomes from not realizing how you can actually hurt your back by doing it too soonor wrong ( bounce, hunch, force, or push through a excercise and neverbreath properly or aware mis/alignment).Ab excercises should be incorporated to support the back...(although you have to be careful with these as well. Too many standard crunches or excercises that stress using only the front/seen layer of the abs has you end up with a bulge not toned abs... plus the strain to the back, neck.It might be better to use a little towel under the small of the back and to diversify ab workout sothat you get to the deeper layers of the abs).
Charish