Does anyone have a video link that shows some ways to add resistance to a reverse crunch? I tried google and didn’t have much success. Mostly fitness bunnies who aren’t even performing reverse crunches but regular ol’ crunches.
You could use the straight bar attachment and a low cable. Lay on your back with your feet in the air, and the bar across your thighs. Might need to grab on to something behind you so a heavy weight doesn’t pull you forward. I’m too lazy to look for a vid, but I think you can picture it.
The most practical way to do this is with a resistance band. You can also do a somewhat different movement, the Band-Resisted Jackknife, as Mike Robertson shows in his new article: Complete Core Training
If you need more resistance on a reverse crunch, you don’t need to do that exercise. Do a hanging knee raise instead. If that is too easy, do hanging leg raises. If that is too easy, hold a dumbbell between your feet.