Do a bridge on a ball then roll down so your body is straight then back up to the bridge position. like this
http://www.eightsandweights.com/2014/12/abs-and-gl...
Ah ok, its like the opposite from the pull ins that i do.
You both push out and pull in.....
Unless you do yours upside down or something?
Yeah plank with feet on ball and pull in and out. And another set of pikes. The bridge part confused me.