This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sesso, H. D. Articles by Lee, I-M. Search for Related Content PubMed PubMed Citation Articles by Sesso, H. D. Articles by Lee, I-M. Pubmed/NCBI databases Medline Plus Health Information Exercise for Children Exercise for Seniors Exercise and Physical Fitness Related Collections Primary prevention Exercise/exercise testing/rehabilitation Acute myocardial infarction Chronic ischemic heart disease Epidemiology

(Circulation. 2000;102:975.)
© 2000 American Heart Association, Inc.

Clinical Investigation and Reports

Physical Activity and Coronary Heart Disease in Men

The Harvard Alumni Health Study

Howard D. Sesso, ScD; Ralph S. Paffenbarger, Jr, MD, DrPH; I-Min Lee, MBBS, ScD

From the Department of Epidemiology (H.D.S., R.S.P., I.-M.L.), Harvard School of Public Health, Boston, Mass; the Division of Preventive Medicine (H.D.S., I.-M.L.), Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Mass; and the Division of Epidemiology (R.S.P.), Stanford University School of Medicine, Stanford, Calif.

Correspondence to Howard D. Sesso, ScD, Brigham and Women’s Hospital, 900 Commonwealth Ave East, Boston, MA 02215. E-mail hsesso{at}hsph.harvard.edu

	Abstract

Top Abstract Introduction Methods Results Discussion References

 
Background—The quantity and intensity of physical activity required for the primary prevention of coronary heart disease (CHD) remain unclear. Therefore, we examined the association of the quantity and intensity of physical activity with CHD risk and the impact of other coronary risk factors.

Methods and Results—We followed 12 516 middle-aged and older men (mean age 57.7 years, range 39 to 88 years) from 1977 through 1993. Physical activity was assessed at baseline in kilojoules per week (4.2 kJ=1 kcal) from blocks walked, flights climbed, and participation in sports or recreational activities. During follow-up, 2135 cases of incident CHD, including myocardial infarction, angina pectoris, revascularization, and coronary death, occurred. Compared with men expending <2100 kJ/wk, men expending 2100 to 4199, 4200 to 8399, 8400 to 12 599, and 12 600 kJ/wk had multivariate relative risks of 0.90, 0.81, 0.80, and 0.81, respectively (P for trend=0.003). When we considered the independent effects of specific physical activity components, only total sports or recreational activities (P for trend=0.042) and vigorous activities (P for trend=0.02) were inversely associated with the risk of CHD. These associations did not differ within subgroups of men defined by coronary risk factors. Finally, among men with multiple coronary risk factors, those expending 4200 kJ/wk had reduced CHD risk compared with men expending <4200 kJ/wk.

Conclusions—Total physical activity and vigorous activities showed the strongest reductions in CHD risk. Moderate and light activities, which may be less precisely measured, showed nonsignificant inverse associations. The association between physical activity and a reduced risk of CHD also extends to men with multiple coronary risk factors.

Key Words: exercise • coronary disease • epidemiology • risk factors • men

	Introduction

Top Abstract Introduction Methods Results Discussion References

 
Coronary heart disease (CHD) is the leading cause of death in the United States, accounting for >700 000 deaths in 1996.¹ Several studies have confirmed the overall benefit of physical activity in reducing the risk of CHD.² Still, more than 60% of American adults are not regularly active.³ The necessary quantity and intensity of physical activity for the primary prevention of CHD remain unclear. Few studies have simultaneously considered physical activity of different intensities with the risk of CHD. Some reports suggest that only participation in vigorous activities is associated with reductions in CHD risk,^{4 5 6 7 8} whereas others extend benefits to moderate activities.^{9 10 11 12} Two recent trials indicate that incorporating moderate-intensity activities into the lifestyle may have benefits on coronary risk factors comparable to those derived from structured exercise programs.^{13 14}

Therefore, we sought to update earlier findings on physical activity and risk of CHD in the Harvard Alumni Study¹⁵ by examining the quantity, type, and intensity of physical activity in 1977. We also assessed whether, given the multifactorial etiology of CHD, physical activity impacts the risk of CHD in the presence of other coronary risk factors.

	Methods

Top Abstract Introduction Methods Results Discussion References

 
Subjects
The Harvard Alumni Study is an ongoing cohort study of men matriculating as undergraduates at Harvard University between 1916 and 1950 that was initiated in 1962. For the present study, we were interested in 17 835 men who returned the 1977 questionnaire. We excluded 2863 men reporting physician-diagnosed cardiovascular disease or cancer and 607 men with missing data on physical activity or other coronary risk factors. We successfully followed 12 516 (87.1%) of the remaining 14 365 men; those successfully followed were the men who returned questionnaires in 1988 or 1993 or died by the end of 1993.

Assessment of Physical Activity and Other CHD Risk Factors
We estimated an index of weekly energy expenditure in 1977 from the reported daily number of flights of stairs climbed, city blocks walked, and sports or recreational activities engaged in during the past year.¹⁶ For each sport or activity, we asked for details regarding the frequency (weeks per year) and duration (time per week when active). This assessment of physical activity is both reliable and valid.^{17 18 19 20 21} We estimated that climbing up and down a flight of stairs (1 flight=10 steps) daily expended 59 kJ/wk (4.2 kJ=1 kcal)²² and that walking a city block (1 block=1/12 mile=0.13 km) daily expended 235 kJ/wk.²³ Each activity was assigned a multiple of resting metabolic rate (MET score).²⁴ Because resting metabolic rate is 4.2 kJ/kg body wt per hour, we estimated the average weekly energy expenditure for each activity by multiplying its MET score by body weight and hours per year and then dividing by 52. We summed kilojoules per week from flights climbed, blocks walked, and all sports or recreational activities and categorized this into <2100, 2100 to 4199, 4200 to 8399, 8400 to 12 599, and 12 600 kJ/wk (or <500, 500 to 999, 1000 to 1999, 2000 to 2999, and 3000 kcal/wk, respectively).

We next examined the type and intensity of physical activity. Men were categorized into approximate fifths of flights climbed (2 flights=1 story), walking (1 block=0.13 km), and total energy expended from sports or recreational activities. We then separately calculated and categorized energy expenditure from vigorous (6 METs), moderate (4 to <6 METs), and light (<4 METs) activities.²⁵

On the 1977 questionnaire, we also collected information on age (in years), cigarette smoking (nonsmoker or current smoker [20 or >20 cigarettes/d]), alcohol consumption (none, <100, or 100 g/wk), early parental death at <65 years (yes or no), weight and height (combined into body mass index [kg/m²] and categorized as <22.5, 22.5 to <23.5, 23.5 to <24.5, 24.5 to <26, and 26 kg/m²), physician-diagnosed hypertension (yes or no), and physician-diagnosed diabetes mellitus (yes or no).

Ascertainment of CHD Occurrence
We ascertained cases of first CHD (including myocardial infarction, angina pectoris, coronary artery bypass graft surgery, and percutaneous transluminal coronary angioplasty) through self-reports on follow-up questionnaires sent in 1988 and 1993. The year of diagnosis was taken as the earliest reported year of diagnosis for any event from the 2 questionnaires. If different events occurred in the same year, the event was selected in hierarchical fashion: myocardial infarction, angina pectoris, revascularization, and then death. Self-reported physician-diagnosed CHD has been validated in this cohort.¹⁵ In addition, deaths were compiled continuously by the Harvard Alumni Office, which maintains a listing of deceased alumni. We traced deaths through the end of 1993. For each reported death, we requested and obtained death certificates from the appropriate state. We included deaths with either underlying or contributing causes from CHD. To verify an earlier observation that mortality follow-up was >99%,¹⁵ we used the National Death Index²⁶ to determine whether 500 men thought to be alive through 1992 died between January 1, 1988, and December 31, 1992. We positively identified 2 of these 500 men as deceased, thereby estimating our mortality follow-up rate to be 99.6%.

Data Analyses
We first examined the distribution of characteristics according to categories of physical activity by using ² tests to compare proportions and ANOVA to compare means. We calculated person-years of follow-up from 1977 to the year in which CHD was first reported, the year of death, or the year of return of the latest questionnaire, whichever occurred first. Relative risks (RRs) and 95% CIs for CHD were calculated by the Cox proportional hazards model; the lowest physical activity category was used as the referent. The proportional hazards assumption was satisfied for total physical activity. Models were first adjusted for age, and multivariate models were further adjusted for the coronary risk factors described above. Linear trend tests treated the 5 categories of physical activity as a single ordinal variable by using the median values for each category. Parallel analyses were performed for each type and intensity of physical activity, further adjusting for other components of physical activity to examine the independent association of each type of activity with CHD risk. We also examined whether any coronary risk factors modified the association between physical activity and CHD.

In light of the multifactorial etiology of CHD, we further sought to examine physical activity in the presence of other coronary risk factors. We dichotomized 6 coronary risk factors: cigarette smoking (current smoker or nonsmoker), history of hypertension (yes or no), history of diabetes (yes or no), body mass index (25 or <25 kg/m²), alcohol consumption (none or any), and early parental death (yes or no). Men were classified according to number of coronary risk factors. Men without these risk factors served as the referent. RRs then were calculated separately by baseline physical activity (<4200 or 4200 kJ/wk) and age (<60 or 60 years) to equally distribute CHD events and enhance power.

In secondary analyses, we excluded men developing CHD during the first 3 years of follow-up to minimize any bias due to illnesses that might have affected baseline physical activity. Sensitivity analyses assessed whether altering the cut points for the various types of physical activity appreciably altered the RR estimates. Finally, we updated physical activity in a subset of 6897 men returning both the 1977 and 1988 questionnaires who were free of CHD through 1988 and followed them for 5 years through the end of 1993 (424 cases).

	Results

Top Abstract Introduction Methods Results Discussion References

 
The mean±SD age at baseline in 1977 was 57.7±9.0 years (range 39 to 88 years), and the mean±SD body mass index was 24.4±2.8 kg/m². Table 1 compares men by physical activity category according to coronary risk factors at baseline. Men with higher levels of energy expenditure tended to be younger (P<0.001), to consume more alcohol (P<0.001), and to be less likely to smoke (P<0.001) and have diabetes mellitus (P=0.01) and hypertension (P<0.001). There were no appreciable differences in baseline coronary risk factors comparing men in the study population with those excluded because of loss to follow-up (data not shown).

View this table: [in this window] [in a new window]   Table 1. Characteristics of 12 516 Harvard Alumni According to Energy Expenditure in 1977

The mean±SD physical activity level was 8362±8215 kJ/wk. On average, the relative contribution of energy from flights climbed, blocks walked, and total sports or recreational activities was 5.7%, 36.8%, and 57.4%, respectively. Sports or recreational activities were reported by 74.1% of the men. Most of the energy was expended on moderate (4 to <6 METs) and vigorous (6 METs) activities, which contributed 37.4% and 56.1%, respectively, to the total energy expended from sports or recreational activities.

During 166 410 person-years of follow-up, 2135 CHD cases (1295 identified through questionnaires and 840 from death certificates) occurred. Of the 2135 cases, 512 were from angina pectoris, 576 from myocardial infarction, 207 from revascularizations, and 840 from CHD death (709 as the primary cause). We found an L-shaped association between increasing levels of physical activity and the risk of CHD in the age-adjusted model (Table 2) (P for trend<0.001), with no additional reduction in risk of CHD for levels >8400 kJ/wk. The addition of coronary risk factors to the model modestly attenuated the age-adjusted RRs, but the L-shaped association remained. We found no appreciable difference in the RRs when we considered CHD identified from questionnaires versus death certificates, when we excluded men with CHD during the first 3 years of follow-up, or when we did not adjust for body mass index, hypertension, or diabetes, which are biological mediators. When a stricter definition of CHD (angina pectoris, myocardial infarction, or CHD death as the primary cause) was used, the RRs also changed little. Finally, we found no significant evidence that coronary risk factors modified the inverse association of physical activity with CHD risk.

View this table: [in this window] [in a new window]   Table 2. RRs of CHD, 1977 Through 1993, Among Harvard Alumni, According to Levels of Physical Activity in 1977

We then considered whether specific components of physical activity were associated with the risk of CHD (Figure). In multivariate models, we found significant associations of increasing levels of total activities and vigorous activities with the risk of CHD. The lack of a linear association (P=0.08) in multivariate models between kilometers walked per week and CHD may have been due to a threshold effect beyond walking 5 km/wk. If fact, men walking 5 km/wk had a significant (13%) reduced risk of CHD compared with those walking <5 km/wk.

View larger version (52K): [in this window] [in a new window]   Figure 1. RRs of CHD, 1977 through 1993, among Harvard alumni, according to types of physical activity in 1977. RRs were adjusted for age, other components of physical activity, body mass index, alcohol intake, hypertension, diabetes mellitus, smoking status, and early parental death (<65 years). Types of physical activity were categorized as follows: vigorous activity, 6 METs; moderate activity, 4 to <6 METs; and light activity, <4 METs (4.2 kJ=1 kcal).

In sensitivity analyses, cut points >8400 kJ/wk for total energy expended from sports or recreational activities did not result in greater reductions in CHD risk. Levels of energy expenditure >8400 kJ/wk for vigorous activities were associated with a 10% to 20% reduction in the risk of CHD. We found a possible U-shaped association (P for nonlinear trend=0.10) between moderate activity and the risk of CHD, with a nadir in risk among men expending 2100 to 4199 kJ/wk compared with men reporting no moderate activities. Increasing the cut point for the highest category of moderate activity did not result in an elevated risk of CHD compared with the referent category. For light activities, the lack of an association with the risk of CHD remained at even higher cut points.

Next, we examined the association between physical activity and CHD in the presence of other coronary risk factors, stratifying the results according to men aged <60 and 60 years (Table 3). The lower case counts among men with specific single risk factors limited our ability to make definitive conclusions in these categories. Among men aged <60 years, those who were active (4200 kJ/wk) had lower magnitudes of increased CHD risk compared with those who were inactive. Men with single coronary risk factors expending 4200 kJ/wk also had lower RRs of CHD compared with those expending <4200 kJ/wk, with the exceptions of diabetics and smokers. Among men aged 60 years compared with younger men, the magnitudes of RRs of CHD for increasing numbers of coronary risk factors were lower. Compared with physically active men with no risk factors, older men with single coronary risk factors expending 4200 kJ/wk had no increased risk of CHD.

View this table: [in this window] [in a new window]   Table 3. RRs of CHD, 1977 Through 1993, Among Harvard Alumni by Age and Physical Activity Index, According to Coronary Risk Factor Profile

Finally, we considered the joint effect of physical activity measured in 1977 and 1988 on the risk of CHD among 6959 men (424 CHD cases) free of CHD through 1988. Models with physical activity and other coronary risk factors as time-dependent variables did not appreciably alter the main results for physical activity.

	Discussion

Top Abstract Introduction Methods Results Discussion References

 
The present study provides new data from the Harvard Alumni Study on both the quantity and intensity of physical activity and CHD risk among older men, in the context of the new Surgeon General’s recommendations. We found an L-shaped association between physical activity and risk of CHD, with an 20% reduction in CHD risk for total physical activity levels >4200 kJ/wk. A physical activity level of 4200 kJ/wk is consistent with the Surgeon General’s recommendation³ and can be attained by performing activities such as brisk walking, recreational cycling and swimming, home repair, and yard work for 30 min/d on most days of the week.²⁷ In addition, there was a nonsignificant 10% reduction in men expending 2100 to 4199 kJ/wk.

The present study also suggests that vigorous activities are associated with a reduced risk of CHD, whereas moderate or light activities have no clear association with the risk of CHD. Finally, physical activity may favorably affect CHD risk even in the presence of other coronary risk factors. Therefore, an active lifestyle may ameliorate the deleterious effect of concomitant coronary risk factors. In particular, men aged 60 years who expended 4200 kJ/wk may have smaller increases in CHD risk in the presence of coronary risk factors.

The most relevant previous publication from this cohort was published in 1978¹⁵ with the use of data from the 1962/1966 questionnaire in relation to the risk of myocardial infarction. This and other reports on morbidity and mortality from this cohort of Harvard alumni have contributed, in part, to the development of the Surgeon General’s recommendation. In the 1978 article, the cohort consisted of middle-aged men, and information on physical activity was coded in far less detail. Risk estimates were also calculated without adjustment for potential coronary risk factors. The present study adds valuable new information on the association between physical activity and risk of CHD with the use of detailed coding of physical activity from the 1977 questionnaire in relation to CHD risk. As a result, the present cohort consists of older men, with sufficient detail on the quantity, intensity, and type of physical activity to directly address the Surgeon General’s recommendations. Furthermore, we adjusted for known coronary risk factors that confounded the association between physical activity and CHD. Because there are few studies on quantity, type, and intensity of physical activity and the risk of CHD among older men, the present study provided an excellent opportunity to explore these hypotheses.

Recent statements from the Surgeon General,³ the National Institutes of Health Consensus Development Panel on Physical Activity and Cardiovascular Health,²⁸ and the Centers for Disease Control and Prevention and the American College of Sports Medicine²⁷ recommend that every adult should accumulate at least 30 minutes of moderate-intensity physical activity on most, preferably all, days of the week to prevent CHD and other chronic diseases. The decision to expand the recommendation for physical activity to include moderate activities, in addition to vigorous activities, was based on the assumptions that moderate physical activity would be more easily attainable and can be accumulated in either several small daily doses or a single large daily dose. Two recent intervention trials^{13 14} indicate that moderate-intensity physical activity may have benefits on coronary risk factors that are similar to those provided by structured, more vigorous activities. However, these results applied to previously sedentary, overweight, and obese individuals. It remains unclear whether short-term improvements in coronary risk factors result in long-term reductions in CHD risk.

The few studies that have focused on the intensity of physical activity in relation to CHD have yielded inconsistent results. Differences in intensity classifications, adjustment for confounders, and CHD numbers and definitions across studies may account for these results. Whereas the benefits of vigorous-intensity physical activity appear clear,^{4 5 6 7 8 9 10 11 12} the benefits of moderate- or light-intensity activities have been observed in some^{9 10 11 12} but not all^{4 5 6 7 8} studies. We did not find equivalent benefits for vigorous and moderate physical activity in relation to CHD risk. Greater energy expended from vigorous activities was inversely associated with the risk of CHD. In contrast, we found a possible U-shaped association for moderate activities, with the lowest risk of CHD among men expending 2100 to 4199 kJ/wk. This lack of association for moderate activities may reflect the imprecise measurement of these activities compared with vigorous activities²¹ or the difficulty in achieving such high levels of energy expenditure from moderate activities.

Clinical studies have demonstrated that exercise lowers blood pressure²⁹ and improves body composition,³⁰ glucose tolerance, and insulin sensitivity.³¹ In the present study, when we adjusted for some of these biological effects, the RR estimates were only modestly confounded. Other pathways leading to a reduction in CHD risk may be responsible for the observed inverse association, including improvements in HDL cholesterol³⁰ and thrombotic function, including hematocrit, fibrinogen, platelet function, and fibrinolysis.²⁸

Some limitations should be considered in light of our results. First, the measurement of physical activity may be susceptible to misclassification, which would, if random with respect to CHD risk, bias our results toward the null. However, a previous validation study¹⁹ suggests that the average magnitude of misclassification of nonresting energy expenditure may be 630 kJ/wk (150 kcal/wk); thus, we do not expect misclassification to greatly affect our risk estimates. Second, we followed men over a long period, during which physical activity levels likely fluctuated. However, when we updated information on physical activity, our findings were little changed. Third, we are unclear whether our results extend to women. Recent studies have shown both an inverse association^{32 33} and no association^{8 34} with CHD risk. Finally, the lack of control for dietary factors and lipids may introduce residual confounding.

In conclusion, we found an L-shaped association between physical activity and the risk of CHD. Older men should expend at least 4200 kJ/wk in total physical activity to potentially reduce their risk of CHD by 20%. Those expending 2100 to 4199 kJ/wk, slightly lower than that recommended by the Surgeon General,³ had a possible nonsignificant 10% reduction in the risk of CHD. Future research must improve the assessment of moderate and light physical activity to better distinguish whether particular types and intensities of activities derive reductions in CHD risk.

	Acknowledgments

 
This study was supported by grants CA-44854 and HL-34174 from the National Cancer Institute and the National Heart, Lung, and Blood Institute, Bethesda, Md. We are grateful to Stacey DeCaro, Sarah E. Freeman, Tina Y. Ha, Marty Higgins, James B. Kampert, Rita W. Leung, Doris C. Rosoff, and Alvin L. Wing for their help with the College Alumni Health Study.

	Footnotes

 
This is report No. LXXVI in a series on chronic disease in former college students (Harvard Alumni Health Study).

Received February 24, 2000; revision received April 5, 2000; accepted April 7, 2000.

	References

Top Abstract Introduction Methods Results Discussion References

 

1. Peters KD, Kochanek KD, Murphy SL. Deaths: Final Data for 1996. Hyattsville, Md: National Center for Health Statistics; 1998. National Vital Statistics Reports, Vol 47, No. 9.
   
2. Blair SN, Kohl HW, Barlow CE. Physical activity, physical fitness, and all-cause mortality in women: do women need to be active? J Am Coll Nutr. 1993;12:368–371.[Abstract]
   
3. US Department of Health and Human Services. Physical Activity and Health: A Report of the Surgeon General. Atlanta, Ga: US Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion; 1996.
   
4. Morris JN, Everitt MG, Pollard R, et al. Vigorous exercise in leisure-time: protection against coronary heart disease. Lancet. 1980;2:1207–1210.[Medline] [Order article via Infotrieve]
   
5. Morris JN, Clayton DG, Everitt MG, et al. Exercise in leisure time: coronary attack and death rates. Br Heart J. 1990;63:325–334.[Abstract/Free Full Text]
   
6. Lakka TA, Venalainen JM, Rauramaa R, et al. Relation of leisure-time physical activity and cardiorespiratory fitness to the risk of acute myocardial infarction. N Engl J Med. 1994;330:1549–1554.[Abstract/Free Full Text]
   
7. Lee IM, Hsieh CC, Paffenbarger RS Jr. Exercise intensity and longevity in men: the Harvard Alumni Health Study. JAMA. 1995;273:1179–1184.[Abstract]
   
8. Folsom AR, Arnett DK, Hutchinson RG, et al. Physical activity and incidence of coronary heart disease in middle-aged women and men. Med Sci Sports Exerc. 1997;29:901–909.[Medline] [Order article via Infotrieve]
   
9. Leon AS, Connett J, Jacobs DR Jr, et al. Leisure-time physical activity levels and risk of coronary heart disease and death: the Multiple Risk Factor Intervention Trial. JAMA. 1987;258:2388–2395.[Abstract]
   
10. Slattery ML, Jacobs DR Jr, Nichaman MZ. Leisure time physical activity and coronary heart disease death: the US Railroad Study. Circulation. 1989;79:304–311.[Abstract/Free Full Text]
    
11. Shaper AG, Wannamethee G, Weatherall R. Physical activity and ischaemic heart disease in middle-aged British men. Br Heart J. 1991;66:384–394.[Abstract/Free Full Text]
    
12. Paffenbarger RS Jr, Hyde RT, Wing AL, et al. The association of changes in physical-activity level and other lifestyle characteristics with mortality among men. N Engl J Med. 1993;328:538–545.[Abstract/Free Full Text]
    
13. Dunn AL, Marcus BH, Kampert JB, et al. Comparison of lifestyle and structured interventions to increase physical activity and cardiorespiratory fitness. JAMA. 1999;281:327–334.[Abstract/Free Full Text]
    
14. Andersen RE, Wadden TA, Bartlett SJ, et al. Effects of lifestyle activity vs structured aerobic exercise in obese women: a randomized trial. JAMA. 1999;281:335–340.[Abstract/Free Full Text]
    
15. Paffenbarger RS Jr, Wing AL, Hyde RT. Physical activity as an index of heart attack risk in college alumni. Am J Epidemiol. 1978;108:161–175.[Abstract/Free Full Text]
    
16. Lee IM, Paffenbarger RS Jr, Hsieh CC. Time trends in physical activity among college alumni, 1962–1988. Am J Epidemiol. 1992;135:915–925.[Abstract/Free Full Text]
    
17. LaPorte RE, Cauley JA, Kinsey CM, et al. The epidemiology of physical activity in children, college students, middle-aged men, menopausal females and monkeys. J Chronic Dis. 1982;35:787–795.[Medline] [Order article via Infotrieve]
    
18. Siconolfi SF, Lasater TM, Snow RC, et al. Self-reported physical activity compared with maximal oxygen uptake. Am J Epidemiol. 1985;122:101–105.[Abstract/Free Full Text]
    
19. Albanes D, Conway JM, Taylor PR, et al. Validation and comparison of eight physical activity questionnaires. Epidemiology. 1990;1:65–71.[Medline] [Order article via Infotrieve]
    
20. Washburn RA, Smith KW, Goldfield SR, et al. Reliability and physiologic correlates of the Harvard Alumni Activity Survey in a general population. J Clin Epidemiol. 1991;44:1319–1326.[Medline] [Order article via Infotrieve]
    
21. Ainsworth BE, Leon AS, Richardson MT, et al. Accuracy of the College Alumnus Physical Activity Questionnaire. J Clin Epidemiol. 1993;46:1403–1411.[Medline] [Order article via Infotrieve]
    
22. Bassett DR, Vachon JA, Kirkland AO, et al. Energy cost of stair climbing and descending on the college alumnus questionnaire. Med Sci Sports Exerc. 1997;29:1250–1254.[Medline] [Order article via Infotrieve]
    
23. Passmore R, Durnin JV. Human energy expenditure. Physiol Rev. 1955;35:801–840.[Free Full Text]
    
24. Ainsworth BE, Haskell WL, Leon AS, et al. Compendium of physical activities: classification of energy costs of human physical activities. Med Sci Sports Exerc. 1993;25:71–80.[Medline] [Order article via Infotrieve]
    
25. Taylor HL, Jacobs DR Jr, Schucker B, et al. A questionnaire for the assessment of leisure time physical activities. J Chronic Dis. 1978;31:741–755.[Medline] [Order article via Infotrieve]
    
26. National Center for Health Statistics. National Death Index User’s Manual. Hyattsville, Md: Department of Health and Human Services; 1997.
    
27. Pate RR, Pratt M, Blair SN, et al. Physical activity and public health: a recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA. 1995;273:402–407.[Abstract]
    
28. NIH Consensus Development Panel on Physical Activity and Cardiovascular Health. Physical activity and cardiovascular health. JAMA. 1996;276:241–246.[Abstract]
    
29. Duncan JJ, Farr JE, Upton SJ, et al. The effects of aerobic exercise on plasma catecholamines and blood pressure in patients with mild essential hypertension. JAMA. 1985;254:2609–2613.[Abstract]
    
30. Wood PD, Stefanick ML, Williams PT, et al. The effects on plasma lipoproteins of a prudent weight-reducing diet, with or without exercise, in overweight men and women. N Engl J Med. 1991;325:461–466.[Abstract]
    
31. Koivisto VA, Yki-Jarvinen H, DeFronzo RA. Physical training and insulin sensitivity. Diabetes Metab Rev. 1986;1:445–481.[Medline] [Order article via Infotrieve]
    
32. Kushi LH, Fee RM, Folsom AR, et al. Physical activity and mortality in postmenopausal women. JAMA. 1997;277:1287–1292.[Abstract]
    
33. Manson JE, Hu FB, Rich-Edwards JW, et al. A prospective study of walking as compared with vigorous exercise in the prevention of coronary heart disease in women. N Engl J Med. 1999;341:650–658.[Abstract/Free Full Text]
    
34. Sesso HD, Paffenbarger RS Jr, Ha T, et al. Physical activity and cardiovascular disease risk in middle-aged and older women. Am J Epidemiol. 1999;150:408–416.[Abstract/Free Full Text]
    

This article has been cited by other articles:

				C. Pitsavos, S. A. Kavouras, D. B. Panagiotakos, S. Arapi, C. A. Anastasiou, S. Zombolos, P. Stravopodis, Y. Mantas, Y. Kogias, A. Antonoulas, et al. Physical Activity Status and Acute Coronary Syndromes Survival: The GREECS (Greek Study of Acute Coronary Syndromes) Study J. Am. Coll. Cardiol., May 27, 2008; 51(21): 2034 - 2039. [Abstract] [Full Text] [PDF]

				M Hamer and Y Chida Walking and primary prevention: a meta-analysis of prospective cohort studies Br. J. Sports Med., April 1, 2008; 42(4): 238 - 243. [Abstract] [Full Text] [PDF]

				H. C. McGill Jr, C. A. McMahan, and S. S. Gidding Preventing Heart Disease in the 21st Century: Implications of the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Study Circulation, March 4, 2008; 117(9): 1216 - 1227. [Full Text] [PDF]

				S. Yu, C. C. Patterson, and J. W.G. Yarnell Is vigorous physical activity contraindicated in subjects with coronary heart disease? Evidence from the Caerphilly study Eur. Heart J., March 1, 2008; 29(5): 602 - 608. [Abstract] [Full Text] [PDF]

				J. J. Winnick, W. M. Sherman, D. L. Habash, M. B. Stout, M. L. Failla, M. A. Belury, and D. P. Schuster Short-Term Aerobic Exercise Training in Obese Humans with Type 2 Diabetes Mellitus Improves Whole-Body Insulin Sensitivity through Gains in Peripheral, not Hepatic Insulin Sensitivity J. Clin. Endocrinol. Metab., March 1, 2008; 93(3): 771 - 778. [Abstract] [Full Text] [PDF]

				G. S. Metsios, A. Stavropoulos-Kalinoglou, J. J. C. S. Veldhuijzen van Zanten, G. J. Treharne, V. F. Panoulas, K. M. J. Douglas, Y. Koutedakis, and G. D. Kitas Rheumatoid arthritis, cardiovascular disease and physical exercise: a systematic review Rheumatology, March 1, 2008; 47(3): 239 - 248. [Abstract] [Full Text] [PDF]

				J. O. Pedersen, B. L. Heitmann, P. Schnohr, and M. Gronbaek The combined influence of leisure-time physical activity and weekly alcohol intake on fatal ischaemic heart disease and all-cause mortality Eur. Heart J., January 9, 2008; (2008) ehm574v1. [Abstract] [Full Text] [PDF]

				U. N. Toft, L. H. Kristoffersen, M. Aadahl, L. von Huth Smith, C. Pisinger, and T. Jorgensen Diet and exercise intervention in a general population mediators of participation and adherence: the Inter99 study Eur J Public Health, October 1, 2007; 17(5): 455 - 463. [Abstract] [Full Text] [PDF]

				L. L. Haheim, S. Tonstad, I. Hjermann, P. Leren, and I. Holme Predictiveness of body mass index for fatal coronary heart disease in men according to length of follow-up: A 21-year prospective cohort study Scand J Public Health, January 1, 2007; 35(1): 4 - 10. [Abstract] [PDF]

				H. L. Lujan, S. L. Britton, L. G. Koch, and S. E. DiCarlo Reduced susceptibility to ventricular tachyarrhythmias in rats selectively bred for high aerobic capacity Am J Physiol Heart Circ Physiol, December 1, 2006; 291(6): H2933 - H2941. [Abstract] [Full Text] [PDF]

				C. A. McMahan, S. S. Gidding, G. T. Malcom, R. E. Tracy, J. P. Strong, H. C. McGill Jr, and for the Pathobiological Determinants of Atheroscle Pathobiological Determinants of Atherosclerosis in Youth Risk Scores Are Associated With Early and Advanced Atherosclerosis Pediatrics, October 1, 2006; 118(4): 1447 - 1455. [Abstract] [Full Text] [PDF]

				K.-T. Khaw, R. Jakes, S. Bingham, A. Welch, R. Luben, N. Day, and N. Wareham Work and leisure time physical activity assessed using a simple, pragmatic, validated questionnaire and incident cardiovascular disease and all-cause mortality in men and women: The European Prospective Investigation into Cancer in Norfolk prospective population study Int. J. Epidemiol., August 1, 2006; 35(4): 1034 - 1043. [Abstract] [Full Text] [PDF]

				F. Pitta, T. Troosters, V. S. Probst, M. A. Spruit, M. Decramer, and R. Gosselink Quantifying physical activity in daily life with questionnaires and motion sensors in COPD. Eur. Respir. J., May 1, 2006; 27(5): 1040 - 1055. [Abstract] [Full Text] [PDF]

				K I Proper, S G van den Heuvel, E M De Vroome, V H Hildebrandt, and A J Van der Beek Dose-response relation between physical activity and sick leave Br. J. Sports Med., February 1, 2006; 40(2): 173 - 178. [Abstract] [Full Text] [PDF]

				A. Irazusta, S. Gil, F. Ruiz, J. Gondra, A. Jauregi, J. Irazusta, and J. Gil Exercise, physical fitness, and dietary habits of first-year female nursing students. Biol Res Nurs, January 1, 2006; 7(3): 175 - 186. [Abstract] [PDF]

				K. Sundquist, S.-E. Johansson, J. Qvist, and J. Sundquist Does occupational social class predict coronary heart disease after retirement? A 12-year follow-up study in Sweden Scand J Public Health, December 1, 2005; 33(6): 447 - 454. [Abstract] [PDF]

				O. H. Franco, C. de Laet, A. Peeters, J. Jonker, J. Mackenbach, and W. Nusselder Effects of Physical Activity on Life Expectancy With Cardiovascular Disease Arch Intern Med, November 14, 2005; 165(20): 2355 - 2360. [Abstract] [Full Text] [PDF]

				P. Muntner, D. Gu, R. P. Wildman, J. Chen, W. Qan, P. K. Whelton, and J. He Prevalence of Physical Activity Among Chinese Adults: Results From the International Collaborative Study of Cardiovascular Disease in Asia Am J Public Health, September 1, 2005; 95(9): 1631 - 1636. [Abstract] [Full Text] [PDF]

				A. Margeli, K. Skenderi, M. Tsironi, E. Hantzi, A.-L. Matalas, C. Vrettou, E. Kanavakis, G. Chrousos, and I. Papassotiriou Dramatic Elevations of Interleukin-6 and Acute-Phase Reactants in Athletes Participating in the Ultradistance Foot Race Spartathlon: Severe Systemic Inflammation and Lipid and Lipoprotein Changes in Protracted Exercise J. Clin. Endocrinol. Metab., July 1, 2005; 90(7): 3914 - 3918. [Abstract] [Full Text] [PDF]

				U. Ekelund, S. Brage, P. W Franks, S. Hennings, S. Emms, M.-Y. Wong, and N. J Wareham Physical activity energy expenditure predicts changes in body composition in middle-aged healthy whites: effect modification by age Am. J. Clinical Nutrition, May 1, 2005; 81(5): 964 - 969. [Abstract] [Full Text] [PDF]

				H. L. Collins, A. M. Loka, and S. E. DiCarlo Daily exercise-induced cardioprotection is associated with changes in calcium regulatory proteins in hypertensive rats Am J Physiol Heart Circ Physiol, February 1, 2005; 288(2): H532 - H540. [Abstract] [Full Text] [PDF]

				C. K. Roberts and R. J. Barnard Effects of exercise and diet on chronic disease J Appl Physiol, January 1, 2005; 98(1): 3 - 30. [Abstract] [Full Text] [PDF]

				P Leino-Arjas, S Solovieva, H Riihimaki, J Kirjonen, and R Telama Leisure time physical activity and strenuousness of work as predictors of physical functioning: a 28 year follow up of a cohort of industrial employees Occup. Environ. Med., December 1, 2004; 61(12): 1032 - 1038. [Abstract] [Full Text] [PDF]

				D. J Green, A. Maiorana, G. O'Driscoll, and R. Taylor Effect of exercise training on endothelium-derived nitric oxide function in humans J. Physiol., November 15, 2004; 561(1): 1 - 25. [Abstract] [Full Text] [PDF]

J.E. Sharman, J.R. Cockcroft, and J.S. Coombes Cardiovascular implications of exposure to traffic air pollution during exercise QJM, October 1, 2004; 97(10): 637 - 643. [Abstract]<