In My Case, the back was the result of a bad bike accident, I have 3 herniated discs in my lower back which messes with the nerves in my legs. My legs get weak and I have folded both knees sideways tearing the acl and messing up the meniscus as a result. I am hoping that as I loose weight, my back issues will go away and my knees will suffer less for that. 1 week in and counting. Down 1 pant size too.