2
Do a plank with 400 pounds on your back
I like standing cable crunches they’re a little awkward till u get used to them but I find it easier to isolate abs with them
Decline weighted crunches, cable/machine crunches, knee raises on captains chair with weight between feet, crunches on ghd machine
My coach used to have us do planks with plates on our backs matching our bw it was horrible
Haha I once had to do wall sits with a 25 plate on my lap and then my coach would walk back and forth on top of us it was brutal but I loved it
Thank you!