Exercise at Menopause: A Critical Difference

Margaret Burghardt, MD

Disclosures

Medscape General Medicine. 1999;1(3) 

In This Article

Osteoporosis: Benefits of Resistance Training

Many recent studies support the use of muscle-strengthening exercise to attenuate bone loss in menopause. Declines in muscle mass and strength are comparable to the loss of bone mass from young adulthood to old age. Functional losses in muscle are a combination of aging and the sedentary lifestyle often adopted as a part of the aging process. Exercise cannot reverse the effects of time and age, but it can modify and perhaps attenuate the process of deterioration in muscle and bone.

Bone remodeling responds to mechanical stress, including loading, gravity, and muscular contraction. Tennis players have greater BMD in the radius of the dominant versus the nondominant arm.[19] Swimmers have higher-radius BMD than controls.[14,20] The literature does show correlations between muscle strength and regional bone density. A significant positive correlation was found between BMD and back extensor strength in healthy postmenopausal women, even when BMD was corrected for age.[21]

Hughes and associates[22] found that site-specific muscular contraction work does increase BMD, independent of weight, age, smoking status, and calcium supplementation. By controlling for age and body weight, this study was able to assess the role of muscular contraction on bone, independent of gravitational effects. These studies support the role of resistance exercise training, promoting site-specific effects of muscular strength on maintenance of bone mass.

A prospective, randomized trial by Morganti and coworkers[23] indicated that high-intensity strength training results in significant and progressive increases in strength in older women. Large gains in muscle strength are possible if a relatively high intensity of training stimulus (80% of previously established 1RM) is maintained, and if the training load is progressively increased based on frequent 1-RM measurements. Fiatarone and others[24] even noted progressive strength gains in frail 86- to 96-year-old men and women participating in a strength-training program.

Bone density is closely related to the likelihood for future fracture, especially fractures of the hip, vertebral spine, and wrist. A randomized, controlled trial by Nelson and coworkers[25] showed significant increases in femoral neck and lumbar spine BMD in postmenopausal women after a biweekly, year-long, high-intensity resistance-training program. This program also resulted in increased strength and muscle mass. Dynamic balance and overall physical activity levels also increased, decreasing the risk of falls and osteoporotic fractures. Additional strong evidence that an exercise program can decrease falls comes from the FICSIT (Frailty and Injuries: Cooperative Studies of Intervention Techniques) trials,[26] which assessed intervention efficacy in reducing falls and frailty in elderly patients. All interventions included an exercise component for 10 to 36 weeks. Women over age 65 who were randomly assigned to an exercise program had a lower incidence of falls when compared with women in a control group over a 2- to 4-year period. An even greater reduction in the risk of falls was noted if balance training was included in the exercise program.

Fortunately, the much older (ie, over age 75), more frail segment of the population seems to respond well to even low-to-moderate loading activities. This may eliminate the need for the frail elderly to participate in heavy-loading exercise programs, which, while helpful in maintaining bone mass, may paradoxically lead to an increased risk of falls and injuries.

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