flamingo - great point! Didn't think of that, but I was going to suggest that before trying this exercise on horseback, ensure that everyone can acheive the position on the ground without any pain. Most people should be able to, or at least get there after a short period. I can't see there being a problem with back necessarily, but with hips, yes. Other exercises to open the hips are also very helpful for position but again, only when people have no problem with motion in that area to begin with.