Physical exercise in the prevention and treatment of osteoporosis: a review.

Osteoporosis is a disorder characterized by reduced bone strength, diminished bone density, and altered macrogeometry and microscopic architecture. Adult bone mass is the integral measurement of the bone mass level achieved at the peak minus the rate and duration of subsequent bone loss. There is clearly a genetic predisposition to attained peak bone mass, which occurs by a person's mid-20s. Bone loss with age and menopause are universal, but rates vary among individuals. Both peak bone mass and subsequent bone loss can be modified by environmental factors, such as nutrition, physical activity, and concomitant diseases and medications. Osteoporosis prevention requires adequate calcium and vitamin D intake, regular physical activity, and avoiding smoking and excessive alcohol ingestion. Risk of fracture determines whether medication is also warranted. A previous vertebral or hip fracture is the most important predictor of fracture risk. Bone density is the best predictor of fracture risk for those without prior adult fractures. Age, weight, certain medications, and family history also help establish a person's risk for osteoporotic fractures. All women should have a bone density test by the age of 65 or younger (at the time of menopause) if risk factors are present. Guidelines for men are currently in development. Medications include both antiresorptive and anabolic types. Antiresorptive medications--estrogens, selective estrogen receptor modulators (raloxifene), bisphosphonates (alendronate, risedronate, and ibandronate) and calcitonins--work by reducing rates of bone remodeling. Teriparatide (parathyroid hormone) is the only anabolic agent currently approved for osteoporosis in the United States. It stimulates new bone formation, repairing architectural defects and improving bone density. All persons who have had osteoporotic vertebral or hip fractures and those with a bone mineral density diagnostic of osteoporosis should receive treatment. In those with a bone mineral density above the osteoporosis range, treatment may be indicated depending on the number and severity of other risk factors.