I told my excellent PT doctor that I feel my crunches more when I fire my thigh muscles or raise my arms at the same time. His solution: placing an exercise ball in my lap, extending my arms over the top of the ball (and banded together to keep them in place) and crunching into the ball from three sides – my chest, my arms and my thighs. Instead of insane numbers of crunches, I do sustained five-second squeezes, easing into and out of them, very controlled. I alternate to the left side, center and right.

I go into it more at my blog.