Exercise at Menopause: A Critical Difference

Margaret Burghardt, MD

Disclosures

Medscape General Medicine. 1999;1(3) 

In This Article

Exercise in Premenopause: Insurance Against Osteoporosis

While hot flashes, insomnia, and weight gain are commonly identified with menopause, women may not initially perceive the inevitable loss of bone mass that occurs with aging. This decrease in bone density, with the accelerated loss seen early in the postmenopausal years, is of considerable concern. It is estimated that bone mass in women is lost at a rate of 0.75% to 1% per year from age 35 onwards, and this rate increases to 2% to 3% per year at menopause.[12] In the first 5 to 6 postmenopausal years, bone loss is most marked from the trabecular bone of the lumbar spine.

Osteoporosis, the combination of diminished structural trabecular support and lack of bone mineral content common in the menopausal years, increases a woman's vulnerability to fracture (Fig. 1). Osteoporotic fractures often contribute to significant overall morbidity and loss of independence, and they often occur without warning: Osteoporosis may well be asymptomatic until fractures occur.

Age-specific rates of fracture in women compared with those of men. Osteoporosis after menopause increases a woman's vulnerability to fracture. Adapted with permission from Orwol ES, Klein RF: Osteoporosis in men. Endocr Rev (1995;16:87-116), Copyright © 1995, The Endocrine Society. [44]

Obtaining a high peak bone mass in adolescence and young adulthood is of primary importance in preventing osteoporosis and fractures in later life. Research findings indicate that exercise plays a role in forming peak bone mass in this premenopausal population.[13,14]

A cross-sectional study by Dook and colleagues[15] suggests that women entering menopause who have participated in high- and moderate-impact physical activity in their premenopausal years have higher bone mineral density (BMD) than nonathletic controls. Evidence supports a positive correlation between activity levels and bone density (Figs. 2,3). Athletes have higher bone density than nonathletes. Jacobson and colleagues,[14] in comparing college tennis players and swimmers versus controls, found mineral content of the radius bone of the arm to be significantly higher in the athletes. Another study found that runners have higher spine bone density than nonrunners.[16]

Using dual energy x-ray absorptiometry, bone mineral density (BMD) is determined. Evidence supports positive correlation between activity levels and BMD. Photo courtesy of Hologic Inc., Waltham, Mass.
Dual energy x-ray absorptiometry imaging of hip and spine to determine osteoporosis in postmenopausal women. Photo courtesy of Hologic Inc., Waltham, Mass.

Exercise also has been shown to prevent bone loss, even in older women: Krolner and associates[17] studied women of menopausal age who had sustained Colles' fractures and were believed to have low BMD, putting them at greater risk of osteoporosis.

The exercise group increased lumbar spine BMD 3.5%, while BMD in the controls decreased 2.7%. Forearm BMD decreased in controls but was maintained in the exercise group. This suggests that exercise can inhibit or reverse the involutional bone loss associated with aging. Notelovitz and Martin[18] found that while 12 months of aerobic exercise did not significantly increase BMD in the forearm or lumbar spine, the training did attenuate lumbar BMD loss in women less than 6 years after onset of menopause, when loss from this site is most marked.

Weight-Bearing Exercise and Osteoporosis

Although the role of exercise is supported, it is unclear what type, intensity, frequency, and duration of activity would be most effective in preventing bone loss. Weight-bearing activity has usually been advocated by physicians and health professionals. Middle-aged women with a past history of high-impact activity have been found to have higher whole-body and regional leg BMD when compared with nonimpact-activity and sedentary control groups.[15] For example, weight-bearing competitive tennis players (high-impact activity) have greater lumbar bone mass when compared with age-matched competitive swimmers (non-weight-bearing).[14]

A study by Grove and Londeree[16] compared a control nonexercising group with low- and high-impact exercise groups. All the women were postmenopausal. Both exercise groups maintained BMD, whereas the control groups experienced a significant decrease in BMD. There was no difference between the low- and high-impact groups, and the researchers concluded that a low-impact exercise, such as walking, was as effective as high-impact regimens in maintaining BMD, with less chance of injury.

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