Exercise for preventing and treating osteoporosis in postmenopausal women

Background Osteoporosis is a condition resulting in an increased risk of skeletal fractures due to a reduction in the density of bone tissue. Treatment of osteoporosis typically involves the use of pharmacological agents. In general it is thought that disuse (prolonged periods of inactivity) and unloading of the skeleton promotes reduced bone mass, whereas mechanical loading through exercise increases bone mass. Objectives To examine the effectiveness of exercise interventions in preventing bone loss and fractures in postmenopausal women. Search strategy During the update of this review we updated the original search strategy by searching up to December 2010 the following electronic databases: the Cochrane Musculoskeletal Group's Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL) (T h e Cochrane Library, 2010 Issue 12); MEDLINE; EMBASE; HealthSTAR; Sports Discus; CINAHL; PEDro; Web of Science; Controlled Clinical Trials; and AMED. We attempted to identify other studies by contacting experts, searching reference lists and searching trial registers. Selection criteria All randomised controlled trials (RCTs) that met our predetermined inclusion criteria. Data collection and analysis Pairs of members of the review team extracted the data and assessed trial quality using predetermined forms. For dichotomous outcomes (fractures), we calculated risk ratios (RRs) using a fixed-effect model. For continuous data, we calculated mean differences (MDs) of the percentage change from baseline. Where heterogeneity existed (determined by the I-2 statistic), we used a random-effects model.