Yes, so many variables can contribute to osteoporosis. However, as far as exercise, its been clinically proven to build bone - look up the Liftmor clinical trials- but they were lifting HEAVY and only supervised by trained physical therapists. Onero is the name of the program in Australia where they are having real success in building bone in post menopausal older women, some who had previously fractured . Several of these programs are now in the US but only about 4 - on the east coast. Hope for more. I suggest looking them up for what exercise is effective.