Current issues of ACP Journal Club are published in Annals of Internal Medicine


Etiology

Physical activity was associated with a reduced risk for death among postmenopausal women

ACP J Club. 1997 Nov-Dec;127:79. doi:10.7326/ACPJC-1997-127-3-079

Related Content in this Issue
• Companion Abstract and Commentary: Physical activity was associated with lower risk for breast cancer


Source Citation

Kushi LH, Fee RM, Folsom AR, et al. Physical activity and mortality in postmenopausal women. JAMA. 1997 Apr 23/30;277:1287-92.


Abstract

Objective

To evaluate the association between physical activity and all-cause mortality in postmenopausal women.

Design

Cohort analytic study with 7 years of follow-up.

Setting

Community-based study in Iowa, United States.

Participants

40 417 postmenopausal women 55 to 69 years of age at baseline who were participating in the Iowa Women's Health Study.

Assessment of risk factors

Levels of moderate and vigorous physical activity were assessed by a mailed questionnaire at baseline. This questionnaire also covered smoking and dietary habits, alcohol use, personal medical history, weight, and body circumferences.

Main outcome measure

All-cause mortality.

Main results

2260 women died during follow-up. Results were adjusted for age at baseline, menarche, menopause, and first live birth; parity; alcohol intake; total energy intake; cigarette smoking; estrogen use; body mass index at baseline; body mass index at 18 years of age; waist-to-hip ratio; first-degree female relative with cancer; hypertension; education level; and marital status. Compared with women who did not exercise regularly, the relative risk (RR) for death from all causes among women who exercised regularly was 0.77 (95% CI 0.66 to 0.90). This remained unchanged after women who reported cancer or heart disease at baseline or who died during the first 3 years of follow-up were excluded. Increasing frequency of moderate physical activity was associated with a reduced risk for death from all causes; RR for once weekly to a few times/mo was 0.76 (CI 0.63 to 0.91), RR for 2 to 4 times/wk was 0.70 (CI 0.58 to 0.85), and RR for > 4 times/wk was 0.62 (CI 0.50 to 0.78) (P < 0.001 for trend). Reduced risk for death with increased physical activity was seen for cardiovascular diseases (RR 0.72, CI 0.54 to 0.95) and for respiratory illnesses (RR 0.33, CI 0.16 to 0.67). Women who engaged in moderate physical activity as infrequently as once/wk and did no vigorous physical activity also showed a reduced risk for death (RR 0.78, CI 0.64 to 0.96).

Conclusion

Physical activity was associated with a reduced risk for death among postmenopausal women.

Source of funding: National Institutes of Health.

For article reprint: Dr. L.H. Kushi, Division of Epidemiology, University of Minnesota School of Public Health, 1300 South 2nd Street, Suite 300, Minneapolis, MN 55454-1015, USA. FAX 612-624-0315.


Commentary

Physical activity has been increasingly on the minds of patients and physicians, most notably because of the 1996 Summer Olympics and the Surgeon General's Report on physical activity and health (1). The editorial accompanying the article by Thune and colleagues asked whether exercise was beneficial and how much was necessary to obtain a benefit (2). I would adapt this to the following 3 questions: 1) What benefits can women expect from exercise? 2) How much exercise is necessary for women to obtain these benefits? and 3) How can we get our sedentary patients to exercise?

To the first question, I would answer that women who are more active experience a variety of benefits. As shown in the study by Kushi and colleagues, women who were more active had lower overall and cardiovascular mortality. In the study by Thune and colleagues, a lower incidence of breast cancer was found among women who exercised regularly. In other studies, exercise was shown to prevent hypertension, diabetes, obesity, osteoporosis, and many other conditions. Physical activity is an effective treatment for hypertension, hyperlipidemia, and depression (1).

The answer to the second question about how much exercise is enough depends on which benefit is being considered. Kushi and colleagues found that postmenopausal women who exercised moderately once a week had a 24% reduction in total mortality compared with sedentary women. It was unclear whether the group of women who exercised daily did substantially better. It is important to note that the amount of vigorous exercise seemed to have no effect because the benefit was more dependent on the amount of moderate activity. On the other hand, Thune and colleagues found a reduced incidence of breast cancer only in the women who spent ≥ 4 hours a week exercising vigorously to keep fit or those who participated in competitive sports but not in the women who spent ≥ 4 hours a week walking, bicycling, or doing other moderate exercise. This exercise classification scheme resulted in over two thirds of the study sample being in the moderate exercise group. It is unclear whether the lack of benefit observed for moderate exercise is because of this classification (which makes it more difficult to show a difference) or because there was, in fact, no benefit.

Finally, the crucial issue is the answer to the third question: How do we as clinicians get our patients to exercise? Patients usually know that they should exercise, and almost all physicians think that exercise is important. A useful model is called the "Stages of Change" or "Transtheoretical Model," (3) which posits that people move through a series of 5 stages. For exercise, the first would be lack of interest in exercise (precontemplation), followed by interest in exercise but not doing any (contemplation). Next would be interest in exercise and doing so occasionally (preparation), followed by exercising regularly (initial action and then maintenance). Our goal as clinicians is to do 2 things: 1) assess the stage where our patients are and 2) give them advice to help move to the next stage. Practically speaking, patients who are interested in exercise but not currently active can be helped to develop a plan and a start date. Those who are not interested in exercise can be given literature to read to help convince them that it is beneficial and feasible. For patients who do not exercise because they see no benefit, these 2 articles provide additional evidence that it is indeed good for them.

Scott E. Sherman, MD, MPH
Ann L. Mai, MD
Veterans Affairs Center for the Study of Healthcare Provider BehaviorSepulveda, California, USA

Scott E. Sherman, MD, MPH
Veterans Affairs Center for the Study of Healthcare Provider Behavior
Sepulveda, California, USA

Ann L. Mai, MD
Veterans Affairs Center for the Study of Healthcare Provider Behavior
Sepulveda, California, USA


References

1. U.S. Department of Health and Human Services. Physical activity and health. A report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, 1996.

2. McTierman A. Exercise and breast cancer—time to get moving? N Engl J Med. 1997; 336:1311-2.

3. Prochaska JO, DiClemente CC, Norcross JC. In search of how people change. Applications to addictive behaviors. Am Psychol. 1992;47:1102-14.