Background: Osteoporosis is a condition resulting in an increased risk of skeletal fractures due to a reduction in the density of bone tissue. Prevention of osteoporotic-related fractures is dependent on the ability to detect individuals with low bone mass, including those women who are asymptomatic. Treatment of osteoporosis involves the use of either anti-resorptive (e.g. estrogen and bisphosphonate) or bone formation agents (e.g. fluoride and PTH). The value of exercise as an intervention for the prevention of postmenopausal bone loss is a controversial subject.
Objectives: To examine the effectiveness of exercise therapy at preventing bone loss and fractures in postmenopausal women.
Search strategy: We searched the Cochrane Musculoskeletal Group's specialised register, MEDLINE, EMBASE, Current Contents and the Cochrane Controlled Trials Registry up to January 2000 according to the methods suggested by Dickersin et al and Haynes et al and the Cochrane Handbook. We hand searched reference lists and consulted content experts.
Selection criteria: This review was proceeded by a peer reviewed protocol published in the Cochrane Library. Two reviewers independently selected all randomized controlled trials (RCTs) which met our predetermined inclusion criteria.
Data collection and analysis: The same two reviewers abstracted the data using predetermined forms and assessed trial quality using a validated assessment tool. For dichotomous outcomes (fractures), relative risks were calculated using fixed effects models. For continuous data, weighted mean differences (WMD) of the percentage change from baseline were calculated. Where heterogeneity existed (determined by a chi square test), a random effects model was used.
Main results: Eighteen randomized controlled trials (RCTs) met the inclusion criteria. The trials had a mean methodological quality score of 2.53. Aerobics, weight bearing and resistance exercises were all effective on the BMD of the spine. The WMD for the combined aerobics and weight bearing program on the spine was 1.79 [95%CI (0.58, 3.01)]. The analyzed results showed walking to be effective on both BMD of the spine 1.31[95%CI (-0.03, 2.65) and the hip 0.92[95%CI (0.21, 1.64). Aerobic exercise was effective in increasing BMD of the wrist 1.22[95%CI (0.71, 1.74)].
Reviewer's conclusions: Aerobics, weight bearing and resistance exercises are all effective in increasing the BMD of the spine in postmenopausal women. Walking is also effective on the hip. The quality of the reporting of the trials in the meta-analysis was low, in particular, in the areas of allocation concealement and blinding.