Hi...I just did Core Max segment #2 tonight for the first time and it was a lot harder than I thought it would be. Here's my problem: I can't remember the name Cathe calls this move, so I'll try to explain it the best that I can. It's when you're on your back and you are passing the ball back and forth between your legs and your hands. So as your legs come up, your arms come up and as your legs go down, so do your arms. How do I prevent my back from arching off the ground? This is VERY hard for me to do this move. Any suggestions? Thanks.