Sue, Your trainer is partially right- you should spend some time running upright and concentrating on your form. However, if your core is not strong enough to hold you there then it will be tough. Runner's World had an article about runner specific abdominal exercises that was awesome. As I mentioned, I've been doing them for over a year now and have seen a HUGE difference in my core strength and running form. I spent the better part of last evening looking for that article but wasn't able to find it (yet). I thought it was in the Nov. 05 issue but apparently I was wrong (perhaps it was June or July of that year). I'm going to keep looking and I think that my friend has that issue so either way I should be able to come up with it soon. Descibing the exercises would be much harder than having you actually look at them so I included my email address with this post if you want to have me send a copy of the article to you. If you want me to send it to you via regular mail I'm happy to do that- just email me your address. Otherwise if that creeps you out and you want me to try to describe the exercises I can do that also. Just let me know!