While there is little research in this area, some practitioners believe that unusual twists or bends (especially forward) can create enough torque on fragile vertebra to cause fractures in someone with osteoporosis. Recommendations for someone who has osteopenia (low bone density) are different. Because they are at reduced risk for spontaneous fractures, they can do more exercises that involve bending and rotating the torso. It is important to focus on bending and rotating in a smooth and controlled manner as opposed to "twisting" and being very careful not to move too quickly or to progress too rapidly with yoga poses. The key here is to progress slowly and to realize that your bones take much longer than your muscles to get strong. Finally, if someone has osteopenia or osteoporosis they need to talk with their doctor about a complete treatment plan, which may include medication management, the recommended amounts of calcium and vitamin D along with exercise as the best way to reduce the risk of fractures.