Is it possible to do the last portion of the exercise, before you go into the negative on a door?
I ask this because I can't get/push my back into the door to pull my hips up to shoulder height - I think this may be because my door moves a little (weights to hold it open) and also that I have to use a chin-up grip to hold me up.
Is it impossible with this type of setup, or am I just weak?