Dr. Loren Fishman, Columbia University School of Medicine, is a yoga practitioner and has a program of 12 poses which are currently being studied and have been shown to improve bone density for mostly all participants with no injuries. There are adaptive poses for those with osteoporosis and osteopenia as well. This program can be accessed via Google, "12 Poses vs Osteoporosis." Best to look at Dr. Fishman's presentation before viewing those of others as he explains the concepts. I've been doing them nearly daily for seven months and recently sent away for the DVD of his second series of 12 Poses.