In order for doing this position you need to have (and I have it of course ) a very good general muscle tone I was given to me by a carer after he asked for me to his gym instructor here in london. As I said before you can get the information about the things you need to do in everywhere . In this exercise after putting a rubber band holded in my hands by my upper back I go down with fist until they touch the floor on their side of my feet and then while still stretching my back I go with the fist to touching my knees while I ark my back by the lumber area (I tried to work very much into this one I don't know if it appears clearly) I do this for ten times .