Sit-ups may seem like a basic and simple exercise. After all, to do this classic exercise, you just have to lie on your back with your knees bent and feet flat on the floor, raise your torso ...

Bored of planks and crunches? Why not try mixing things up with a killer ab exercise that targets most of the muscles in your mid-section? The zombie sit-up isn’t for the faint of heart ...

Want a no-equipment abs exercise that can be done anywhere—but *so over* basic crunches ... core and provides a stability challenge that sit-ups and crunches just can't get ya.