so on the DVD it say to :
1: streach lying
2: do not tuck hips
3: slide foot or whatever
ever other video i can find on youtube says to slghtly tuck hip while keeping rib cage down
The challenge with the ab exercises is to avoid distorting the natural shape of the spine. This is explained on page 198: "Consider placing your hand under your low back, and feel your rib cage pressing against your hand while leaving the pelvis in its origianal forward-tipped position." So, yes, this technique is contrary to what is generally offered from others.