This little treat is called the 'Stability Ball Jackknife'.
Sounds violent, right?
1) Brace your abs. Put your elbows on the bench and rest your shins on the ball.
2) With your arms straight and your back flat, your body should form a straight line from your shoulders to your ankles.
3) Keeping your back straight (don't round it), roll the ball as close to your chest as possible by contracting your abs and pulling it forward.
4) Pause and then return the ball to the starting position by rolling it backward.
5) Do NOT round your lower back.
I would add the following steps:
6) Grunt loudly.
7) Roll sideways off the ball and collapse sprawled out like a giant washed-ashore squid.
8) Vow NEVER to do it again
9).... you know, until tomorrow.....
On the upside - yesterday I wore an outfit I haven't been able to wear for almost a year. Ben gave me the thumbs up when he saw me. Nothing like encouragement from your 17 year old brother :)