Core and back exercises that don't require feet

I'm pretty well set up with upper body strength exercises, thank you very much to all who contributed. But I'm a bit lacking in core and back exercises/stretches that don't require feet. For instances, I can't do planks or bridges because they require weight on the feet. Please rec me stuff along those lines, no feet required.

Also, I have added a tag so those of you who want to skip foot stuff can blacklist it if you have a paid account.

comments