Janda Sit-up question

For those in the know, I want to make sure I'm getting this right.

About the janda sit-up that Pavel talks about, I am assuming the main focus in this move is that you are tensing your legs, glutes, and pulling your heels towards your ass as you peel your back off the floor.

The tensing of the lower extremities takes the hip flexors out of the equation, which in turn puts more emphasis on the abs themselves.

Am I getting this right?

Put the b-ball between your heels and your butt, try to crush it by pulling your heels into your butt, while sitting up slowly.

We use a med ball for the same thing.

Guess I don't need to buy the AbPavelizer then.

I tried it with the basketball and it is impossible! I can't get any leverage without my feet coming off the ground.

I do, do it on a power rack at my gym, though. It has a piece of metal on the bottom that connects to both sides of the rack.

I just place my heels on it and pull against it.

I always find them easy, so I know im doing something wrong :)

I always tense my Hamstrings and Calves, and hold that tension, but when I sit up I can feel my Hip Flexors contracting and helping my abs.

Doesnt holding an Basketball/Medicina ball between your legs and ass arent your legs at a bad angle to do the situps?

Yours,
Beev

I did this last night and got a wicked cramp in my hammy... :(