I'm quite confident that I have never used my abdominal muscles in a correct manner, at least consciously. I've always done my sit-ups and crunches using my back to do the work - and can only do few of them until the muscles in lower back just next to my spine start burning.
This evening my partner tried to show me how they do their sit-ups and crunches, explaining how they make their abs "roll" to get themselves up from the ground, with minimal strain to the back.
When I tried to use that technique, I could get myself up few centimeters, and after that when the "ab rolling" part should happen, I could not get forward at all - like I could not figure out how to do it in the first place, like I couldn't "tell" my abs to do anything like that. I also tried to go down from a sitting position to laying down, I could get down few centimeters, but at the point where my abs should be in control, the only thing is that they are stiff, and I roll over to my back. This is the exercise I tried, only without the leg movement
Also when I have done planks, and trying to pull my belly in, and stiffen up my so-called abs, I can keep it for a while, but it is my back that starts hurting, and not my abs.
So what I am curious is to find out if I am even remotely correct about my idea, and how to potentially test it, and if there are apartment-friendly exercises that would somehow only target abs, where I could not even by accident cheat by using my hips or back to do the motion. Or any other information that might help me in figuring out what my issue is and how to start fixing it.