Correspondence

Exercise and the Prevention of Cardiovascular Events in Women

N Engl J Med 2003; 348:77-79January 2, 2003

Article

To the Editor:

Manson et al. (Sept. 5 issue)1 have convincingly demonstrated in a multiethnic cohort the importance of physical exercise for the prevention of cardiovascular disease in women. Interestingly, walking appeared to be as efficient as vigorous exercise in preventing cardiovascular events. From our viewpoint, the worldwide promotion of walking, not only for exercise, but primarily as a means of transportation, is crucial. In fact, the reduction in the amount of walking not only affects developed countries, but is also a hallmark of urbanization and westernization in developing countries. We recently observed a drastic reduction of walking time and pace in an urban community in sub-Saharan Africa, as compared with a rural sub-Saharan African community (a reduction by a factor of 2 to 4 for walking at a slow pace and by a factor of 6 to more than 10 for walking at a brisk pace).2 The main difference was in the use of walking as a means of transportation.

To assess whether this decreased use of daily walking is also associated with cardiovascular risk factors in developing countries and whether it deserves similar attention, we analyzed data collected cross-sectionally on 1417 women 15 to 83 years of age from a cluster random sampling in a rural community and an urban community in Cameroon. The methods have been described elsewhere.3,4 In all age groups, the body-mass index, blood pressure, and fasting blood glucose level were inversely associated with energy expenditure from walking (Figure 1Figure 1Mean Body-Mass Index, Systolic Blood Pressure, and Fasting Blood Glucose Level, According to Age Group and Level of Energy Expenditure from Walking.). Thus, we strongly believe that in order to attempt to reverse the trend toward an increasing burden of cardiovascular disease in the developing world,5 health-promotion initiatives should target the frequent use of walking as a means of transportation.

Eugène Sobngwi, M.D.
Jean-François Gautier, M.D., Ph.D.
St. Louis University Hospital, 75010 Paris, France
e.sobngwi@wanadoo.fr

Jean-Claude Mbanya, M.D., Ph.D.
University of Yaoundé 1, Yaoundé, Cameroon

5 References

1
Manson JE, Greenland P, LaCroix AZ, et al. Walking compared with vigorous exercise for the prevention of cardiovascular events in women. N Engl J Med 2002;347:716-725
Full Text | Web of Science | Medline

2
Sobngwi E, Mbanya JC, Unwin NC, et al. Physical activity and its relationship with obesity, hypertension, and diabetes in urban and rural Cameroon. Int J Obes Relat Metab Disord 2002;26:1009-1016
CrossRef | Web of Science | Medline

3
Unwin N, Mugusi F, Aspray T, et al. Tackling the emerging pandemic of non-communicable diseases in sub-Saharan Africa: the essential NCD health intervention project. Public Health 1999;113:141-146
CrossRef | Web of Science | Medline

4
Sobngwi E, Mbanya JC, Unwin NC, Aspray TJ, Alberti KG. Development and validation of a questionnaire for the assessment of physical activity in epidemiological studies in sub-Saharan Africa. Int J Epidemiol 2001;30:1361-1368
CrossRef | Web of Science | Medline

5
Murray CJ, Lopez AD. Alternative projections of mortality and disability by cause 1990-2020: Global Burden of Disease Study. Lancet 1997;349:1498-1504
CrossRef | Web of Science | Medline

Author/Editor Response

We thank Dr. Sobngwi and colleagues for sharing their interesting data regarding the inverse relation between energy expenditure from walking and the body-mass index, systolic blood pressure, and fasting glucose level among women in Cameroon. These findings from a developing country mirror the associations observed in the United States and the Western world.1,2

The marked reduction in time spent walking and in the use of walking for transportation in urban as compared with rural communities in sub-Saharan Africa (as described by Sobngwi et al.) is, indeed, a cause for concern as developing countries adopt a more westernized lifestyle. Even within the United States, there is substantial variability in the frequency of walking, for either transportation or recreation, in different cities and communities.3,4 Urban planning and an environmental infrastructure that supports physical activity, such as community walking trails, parks, the presence of sidewalks, scenic surroundings, and perceived neighborhood safety, have been linked to higher levels of walking and overall physical activity in the local population.4,5 Further research on the role of environmental and policy interventions in promoting physical activity is urgently needed.

JoAnn E. Manson, M.D., Dr.P.H.
Brigham and Women's Hospital, Boston, MA 02115
jmanson@rics.bwh.harvard.edu

Philip Greenland, M.D.
Northwestern University Medical School, Chicago, IL 60611

Andrea Z. LaCroix, Ph.D.
Fred Hutchinson Cancer Research Center, Seattle, WA 98109

5 References

1
Physical activity and health: a report of the Surgeon General. Atlanta: Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, 1996.

2
Bensenor I, Rexrode KM, Manson JE. Physical activity and health in women. In: Rippe J, ed. Lifestyle medicine. Malden, Mass.: Blackwell Science, 1999:343-55.

3
Handy SL, Boarnet MG, Ewing R, Killingsworth RE. How the built environment affects physical activity: views from urban planning. Am J Prev Med 2002;23:Suppl:64-73
CrossRef | Web of Science | Medline

4
Brownson RC, Baker EA, Housemann RA, Brennan LK, Bacak SJ. Environmental and policy determinants of physical activity in the United States. Am J Public Health 2001;91:1995-2003
CrossRef | Web of Science | Medline

5
King AC, Castro C, Wilcox S, Eyler AA, Sallis JF, Brownson RC. Personal and environmental factors associated with physical inactivity among different racial-ethnic groups of U.S. middle-aged and older-aged women. Health Psychol 2000;19:353-364
CrossRef | Web of Science

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