I should mention that this exercise is a very good one. In fact, that's the only ab thing I do. I do this exercise mostly because it targets the hip flexors even more than the abs. If you don't lift your back off the backboard, it really targets only hip flexors. And hip flexors are really hard to target, yet they get so much use on the bike and stronger ones will give you a stronger pedal stroke. That said, it does almost nothing to burn fat. I don't even break a sweat doing 3 sets of 30 on it. My belly fat is not moved. BTW, you don't need to so the side-to-side bit. Does nothing for cycling unless you twist your torso from side to side as you pedal.