Hello, there so sorry ,it has been to long. However, I have continued to be in awe of learning so much from some talented people including doctors, scientist and teachers alike. I just spent 9 hrs with one of them. Dr. Stuart M. McGill is a professor of spine biomechanics at the University of Waterloo. WOW AMAZING KNOWLEDGE ABOUT HOW TO BUILD AND MAINTAIN AN AWESOME SPINE !!!!! Can’t wait to use this fantastic stuff In my classes.