I noticed that when I started Dead Lifting Heavy, mainly the Upper part of my Lower Back was working the hardest, and ultimately develops more. However, the lower parts ( I guess you could refer to this as the Lower part of the Lower Back, or the "small of the lower back,"...basically where the hips and low back meet) are very weak, and "seems" that they are not being put into play in my lifting routine. I've tried doing some R- Hypers on a Yoga ball, and I felt that it definitly was working the area. But, I know its no substitute for R-Hypers on a R-Hyper Machine. Also, I know these muscles are weak because they are the first to go sore when I'm standing or walking for long periods. I think these are the same muscles that come into play when throwing a side-kick or back kick. Does anyone know any alternatives to using the Reverse Hyper Maching, because the local gym I go to doesn't have one. Also, I can't manage adding any weights while on the yoga ball...just to cumbersome holding heavy weights with my feet, and I don't get the full R-Hyper motion.