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 low bone mass within individuals, including women who are asymptomatic. Treatment of osteoporosis involves the use of either anti-resorptive (e.g. estrogen, bisphosphonate) or bone formation agents (e.g. fluoride, parathyroid hormone). The value of exercise as an intervention for the prevention of postmenopausal bone loss is a controversial subject.
To examine the effectiveness of exercise therapy in preventing bone loss and fractures in postmenopausal women.
We searched the Cochrane Musculoskeletal Group trials register, the Cochrane Controlled Trials Register MEDLINE, EMBASE, Current Contents up to January 2000, according to the methods suggested by Dickersin 1994 and Haynes 1994 and the Cochrane Handbook. We hand searched reference lists and consulted content experts.
This review was preceded by a peer reviewed protocol published in the Cochrane Library. Two reviewers independently selected all randomized controlled trials (RCTs) that 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.
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)].
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 concealment and blinding.