—Clarence Bass, author of Ripped 1, 2 & 3 talks about the Pavelizer II :
Based on your "hardest situp" article I purchased an Ab Pavelizer 2. I have definitely benefited from this device and share your feeling that, done properly, Janda situps are very difficult.
Actually, it’s quite ingenious. The Evil Russian is devilishly clever.
The new unit won’t let you cheat. If you jerk or try to anchor your feet, bringing the hip flexors into play, your feet come up or the unit slides toward you. It’s a delicate balancing act. You hold the pads down using your leg biceps and glutes -- which takes the hip flexors out of play -- using just enough resistance to keep your feet on the floor, without pulling the unit toward you. The result is what I would call an enhanced crunch. You literally can not sit up all the way.
As Pavel says in the instruction guide which comes with the unit, "Sitting up all the way becomes a mechanical impossibility unless you start with a jerk (a no-no!)." The new unit recruits the glutes and hamstrings big time, taking the hip flexors completely out of the movement, which isolates the abs.
Placing your hands behind your neck makes it a little harder. Don’t pull on your head; you’ll get a headache or a sore neck.
I now use the Ab Pavelizer from workout to workout, and rarely do the regular crunch anymore.