Such a relief - I was worried you'd be complaining I made you waste your money! I'm kicking myself for having had the book for decades and never really having made use of it til now. I am finding the standing "first aid" exercise invaluable, since it can be done even in the middle of a railway station or a run whenever I start to feel my back. I was interested to see a fit looking young man doing it at the gym the other day. I now alternate back extensions and the lying "cobra" type stretch whenever I'm weight training. Good luck with the run.