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In postmenopausal women, combined exercise interventions improve bone mineral density levels at 12 months compared with usual activity

Zhao R, Zhang M, Zhang Q The Effectiveness of Combined Exercise Interventions for Preventing Postmenopausal Bone Loss: A Systematic Review and Meta-analysis. J Orthop Sports Phys Ther. 2017:47:241-51.

Review question

In postmenopausal women, does combining different types of exercise improve bone mineral density (BMD) levels compared with usual physical activity?

Background

As we get older, we lose bone mass or density and are at increased risk for bone fractures. After menopause, bone loss and fracture risk can increase for women. Exercise can increase BMD levels or slow down BMD decreases, although individual exercises seem to work best for specific parts of the body (e.g., spine or hip). Combining different types of exercise may improve BMD levels at more than one part of the body.

How the review was done

The researchers did a systematic review of studies available up to January 2016. They found 11 randomized controlled trials that included 1061 women with an average age of 55 years.

The key features of the studies were:

• women were postmenopausal, didn’t exercise regularly (< 2 hours/week), and didn’t have medical conditions or use drugs that could affect bone density;
• combined exercise interventions mostly included resistance training or body strengthening exercises and aerobic exercise (e.g., walking, jogging, dancing, stepping); some interventions included balance exercises and stretching;
• combined exercise interventions were supervised or partially supervised and mostly done in external centers; some interventions included some exercises that could be done at home;
• combined exercise interventions were mostly compared with usual activity; and
• exercise was mostly done for 3 to 4 days/week (range 2 to 6 days/week) for 12 months or more (range 8 to 30 months).

Women could use calcium and/or vitamin D supplements during the trials.

What the researchers found

Compared with control (mostly usual activity), combined exercise interventions improved BMD levels by a small amount at the lumbar spine, femoral neck, hip, and overall.

Conclusion

In postmenopausal women, combined exercise interventions improve bone mineral density levels by a small amount at 12 months compared with usual activity.

Effect of combined exercise interventions vs control* on bone mineral density (BMD) levels in postmenopausal women

*Most combined exercise interventions were compared with usual activity.

†Amount of improvement compared with control is based on standardized mean differences (SMDs) with the following assumptions: SMD < 0.50 = small improvement; SMD 0.50 to 0.79 = moderate improvement; SMD ≥ 0.80 = large improvement.

‡Most trials reported outcomes at 12 months; some reported outcomes at 8 or 18 months.