core exercises with back pain

Ninerbuff is wise to acknowledge that the specifics of your condition and personal needs are most important in finding safe exercises that would best benefit you.

I wish I could add to the wisdom here, but all I have to offer is my personal experience. Despite my young age, I was diagnosed with osteoporosis a few years ago, so, when it comes to abdominal/core exercises, I try to be especially mindful of any twisting and bending at the waist or in the spine.
I've been on the search for low-impact exercises for a while, and I've found a few that I implement in my routine (of course, to reiterate what Ninerbuff said, follow the expert advice of a qualified health professional before trying anything! - but I am sure you don't need anyone to tell you that ):
Michelle Kenway offers a variety of core exercise and spine strengthening routines on YouTube, particularly for people with osteoporosis.
Below is one of them:
https://www.youtube.com/watch?v=YbxY0wXH1IQ

I also perform standing ab/core exercises (however, I feel like I have a more difficult time really engaging and working my core muscles doing the standing variations as opposed to the traditional exercises, usually performed on the floor).

I have confidence that you will find something that best suits you -- because I know that there are always options out there for any condition!!
I'll be checking back on this thread myself, because, like I said, I've been on the search for a while, and I'm still looking!!

@warmmilky, I have back issues as well and doing ab exercises totally aggravates my back. As soon as I start with ANY thing that makes for ripped abs( Russian twists, crunches, planks with knee to elbows, bicycle twists) I can feel the problems arising. When I stop for four days, boom, back problems go away. Sooo, I do only core exercises now. On all fours with one hand outstretched with opposite foot outstretched for the count of 40 sec. Three sets of that. Side planks ( three sets of 40 sec) and dead bug with opposing hands and feet touches ( three sets of 40 sec). I know it’s not going to give me “ shredded abs” but until my core is strong enough to do more, what choice do I have? My running doesn’t seem to cause any back issues at all ( 5 miles no problem). Let me know what you have found that helps you, too, bc this issue is bugging me as well.

I find this really helpful: https://www.youtube.com/watch?v=LY5Dp0s4IxI.

I have been doing strength weight exercises to improve my core and for my back I do sit down chair exercises my physio has given me to do.