She needs to push down on the bar with the post arm. As soon as that arm goes and the belly starts resting on the bar, they're going to have to either push up at the end or fall. I have them get in front support, push down through the arms, and then pull their legs piked in front so they really have to lock out and push down to keep the arms straight. I see if they can hold that awhile without collapsing (10-15 second for a level 3). That's really for all general bar work, but when they cut over they need that strength too. Usually the ones who struggle with this exercise struggle with "resting" on the bar out of skills or ending with arms bent, chest on bar, falling. Sometimes it's not even raw strength but not quite connecting how to also use all through their shoulders to maintain the position more easily.
This skill also takes some general coordination to let go and regrasp the bar at the correct times. If there's a pommel horse they can work on, front support leg kicks to either side (one leg goes up) with support on the opposite arm and regrasp is a good exercise. They can also try the whole thing on there from the mill circle end position with hands on either pommel, they'll have to push up to swing their leg over the pommel. Those are really bad explanations, sorry.
