MN/PE2 - Caving in?

I'm confused at to what 'caving in' refers to in the instructions for the Straddle Up:

Sit the chest up as high as possible without caving in

 

At first I assumed caving in referred to lumbo-thoracic trunk flexion, and that the move was to be completed purely with a hip movement. Thus, the hip flexors would be shortening but the abdominal muscles would just be working isometrically stabilising the trunk in a 'neutral' position.

But the videos pretty clearly show some trunk flexion (as in MN/PE1 and MN/PE3 too), as evidenced by the skin folding in on itself in the abdominal region. But then other instructions point to keeping the back flat, which would also suggest not allowing trunk flexion (by not allowing kyphosis of the lumbar spine).

So is a certain level of trunk flexion ok? How much do you have to flex at the trunk to 'cave in' the chest?

might be a cultural thing but what I understood from caving in is not allow the form to collapse while performing the move. the legs move upwards in a V trajectory and perform the sitting up portion just as MN/pe1 & 2

edit:english is not my first language, on the hand, i've developed the habit of leaning more towards visualization, so i just follow what i see on the course f i have a doubt about the text

I read it as sitting up and not allowing specfically the chest to cave in, as in back rounding, shoulders hunching. So you work to maintain the flat back.

As an NB looking *up* rather than *forward* helps me with this, similar to hollow body rocks.

Charm said:

As an NB looking *up* rather than *forward* helps me with this, similar to hollow body rocks.

And once again, we find a handy little tip hiding as an almost throwaway comment about something else. (c:

thanners said:

And once again, we find a handy little tip hiding as an almost throwaway comment about something else. (c:

While this cue helped me get the motion down for Mn 1+2 originally, I now look forward doing them so y'know, take what you need and discard it if your chest is already... uncaved.

Edit;

Also, the demo video clearly shows em looking forward, so really don't stress about that cue. I don't really think it's useful past possibly ironing hunched shoulders out of Mn 1-3.