I'm not sure how is it called correctly. When you're on a chinup bar and lift your straight legs up to your face. An old o-lifting soviet exercise. I used to do it when I wasn't lazy about training abs. 3x10 no swinging. I guess it's the hardest exercise for core. What do you think of them? They say leg raises work your hip flexors, but is it a bad thing? I feel it in my abs heavily anyway. I'm thinking it the only ab exercise actually worth doing.