The importance of physical activity for health is well recognized, but little is known about the influence of physical activity on pulmonary function. We have examined whether physical activity could slow down the decline in pulmonary function among the southwestern rural Finnish cohort of the Seven Countries Study. Physical activity was estimated by kilometers walked, cycled, and skied daily. We had complete data for 429 men for 10 years, 275 men for 20 years, and 186 men for 25 years. During the first 10 years, the decline in FEV was 9.8 ml/year less among men in the highest tertile of baseline physical activity than in men in the lowest tertile. According to the mean physical activity over either 20 or 25 years, men in the highest tertile also lost less pulmonary function (p = 0.009 and p = 0.043, respectively). A similar beneficial effect was observed in all smoking categories. In mortality analysis, continued high physical activity and an increase in activity to high level were associated with lower mortality. In conclusion, results indicated that physical activity is associated with a slower decline in pulmonary function and with lower mortality, and thus, middle-aged and older people should be encouraged to enjoy exercise.
Physical activity can enhance health in many ways. Physical training has been shown to increase muscular strength (1), to improve cardiovascular performance (2, 3), and to reduce obesity (4). Physical exercise has also been found to prevent premature death (5) and promote longevity (6–9). However, it is not known whether physical activity can retard the long-term, age-dependent deterioration of pulmonary function.
The aging process itself results in a decline in pulmonary function (10, 11); the major environmental factor that modifies the effects of aging on pulmonary function is smoking (11–15). However, there may be other factors that could modify the decline in pulmonary function in addition to smoking. In previous cross-sectional studies, regular exercise training and good physical fitness have been related to better pulmonary function (16–21). In one longitudinal study, changes in physical activity positively correlated with the level of FVC between the ages of 13–27 years (22). In another longitudinal study, those who participated in vigorous activity showed a slower rate of decline in FEV during a 3.7-year follow-up (23). However, there is no prospective evidence for any association between physical activity and long-term changes in pulmonary function in middle-aged and older individuals.
In this study, we examined the influence of physical activity on the longitudinal decline in pulmonary function among middle-aged men. We evaluated the decline in pulmonary function according to the baseline physical activity and mean physical activity during the follow-up. We also studied how changes in physical activity level during the follow-up had affected pulmonary function and the survival prospects of the participants.
In 1959, all men (n = 1,711) aged 40–59 years from two rural areas in Finland were invited to participate in an international longitudinal study called the Seven Countries Study (24–26). Reexaminations for the Finnish cohorts were performed in 1964, 1969, 1974, 1984, 1989, and 2000. The latest examination did not include a measurement of pulmonary function. This study started in 1964 when habitual physical activity was assessed by an interview (24, 25) and includes only the southwestern cohort (n = 888 in 1959) in whom physical activity was measured more extensively (5).
In the southwestern cohort, there were 675 men in 1964 for whom data were available on baseline physical activity. A total of 525 men survived until 1974, and there were complete data on physical activity, smoking habits, and decline in pulmonary function for 429 individuals between 1964 and 1974. Of those 429 men, 295 subjects survived until 1984, and for 275 of these subjects, data on physical activity were available in 1984. Finally, in 1989, 207 subjects were still alive, and for 186 of these subjects, there were complete data on physical activity.
In 1964, commuting and leisure time physical activity as well as occupational activity were recorded by a trained nurse according to a standard questionnaire that was developed for the Seven Countries Study (25). In the questionnaire, there were six standard questions about habitual walking, cycling, and cross-country skiing. The questions concerned kilometers walked daily (last year), months of cycling (last year), cycling per day per week, kilometers cycled per day per week, months of cross-country skiing, and kilometers skied during the whole winter. In addition, the interviewer classified every subject into one of four categories according to occupational activity: sedentary and light (mostly office work), moderate (e.g., shop keeping), heavy (mainly farming), and very heavy (mainly lumberjacking) (5). In 1984, the questions concerning cross-country skiing were omitted, but the same four questions about walking and cycling remained. Because all men had retired by 1984, the question concerning occupational activity was no longer applicable. In 1989, the interview on physical activity also included the same four questions about walking and cycling.
The questions of physical activity provided the possibility to estimate the mean kilometers walked, cycled, and skied per day in 1964 and the mean kilometers walked and cycled daily in 1984 and 1989. In an attempt to construct a sum variable of physical activity from the differently strenuous activities, a multiple of resting metabolic rate (MET score) (27) was assigned to every activity describing energy expenditure in each activity. The MET is the ratio of metabolic rate during the activity compared with the metabolic rate at rest (28). Because the duration of activity was not enquired, the intensity of each activity had to be estimated as being the same for all subjects (the mean intensity of walking was estimated to be 4.8 km/hour, which corresponds to four METs, the mean intensity of cycling 12.9 km/hour corresponding to five METs, and the mean intensity of skiing 6.4 km/hour corresponding to nine METs) (27). Because one MET is approximately 1 kcal/kg (= 4.2 kilojoules [kJ]/kg) per hour, energy expenditure in kJ for each physical activity was computed by multiplying its MET score by 4.2, body weight in kilograms, and kilometers per day of activity divided by the estimated intensity of activity. The following equations for daily activities were derived:
![]() |
![]() |
![]() |
Then energy expenditure of daily walking, cycling, and skiing was summed to provide baseline physical activity per day (kJ/day). These values were classified into three tertiles. Tertile limits for baseline physical activity were less than 734 kJ/day, 743–1,361 kJ/day, and more than 1,361 kJ/day. Occupational activity was taken into account in the analyses as a cofactor.
Physical activity in 1984 (kJ/day) was obtained by summing the energy expenditure from walking and cycling. To estimate the mean physical activity throughout the 20 years, baseline physical activity was added to physical activity in 1984, and then that sum was divided by two. The quotients were classified into tertiles using the same limits as for baseline physical activity.
Physical activity in 1989 (kJ/day) was obtained by summing energy expenditure from walking and cycling. To estimate the mean physical activity throughout the 25 years, baseline physical activity and physical activity in 1984 were added to physical activity in 1989, and then the sum was divided by three. The quotients were classified into tertiles with the same limits as at the baseline.
In this study, FEV0.75 derived from spirometric tests was used as a measurement of pulmonary function (when the Seven Countries Study started during the 1950s, FEV0.75 was used as a measure of obstruction). Between 1964 and 1974, the spirometry was performed with the McKerrow spirometer (as described previously in detail) (26). In 1984 and 1989, spirometric recordings were performed with the Vitalograph (as explained previously in detail) (15).
The adjustment of FEV0.75 values for height was achieved by dividing the observed values by the square of each subject's standing height and then multiplying these figures by the square of the mean sample height (12). The annual change in height-adjusted FEV0.75 values was calculated by using within-person linear regression for each subject for whom at least three acceptable FEV0.75 measurements were available. Of all of the subjects from whom we had data on baseline physical activity, a total of 468 men had three measurements of pulmonary function during 1964–1974 (with full data on the smoking habits for 429 men). A total of 26 men with data on physical activity and smoking were excluded from the study because they had only two measurements of pulmonary function between 1964 and 1974. Those subjects for whom we had data on pulmonary function and smoking habits but with missing data on physical activity (n = 70) did not show a different decline in FEV0.75 compared with those men from whom we had data on activity. Of the men with data on physical activity over the 20 years (n = 275), 8 subjects had undergone three and 267 had had four measurements of pulmonary function during the period 1964–1984. Of the men for whom we had data on physical activity over the 25 years (n = 186), 2 had undergone three, 16 had had four, and 168 had taken part in all five measurements of pulmonary function between 1964 and 1989.
The recording of smoking habits has been described in detail previously (15, 26). For this study, men were classified into never-smokers, quitters, and continuous smokers. During the first 10 years, quitters were either past smokers in 1964 or those baseline smokers who quit smoking permanently between 1964 and 1974. During 20–25 years, those recorded as quitters were baseline past smokers or those subjects who gave up smoking between 1964 and 1984. To be recorded as a quitter in an examination, a subject had to have given up smoking more than 1 year previously. Smokers who gave up smoking only after 1984 were included as continuous smokers. The duration of smoking was measured in 1959 by asking the number of years of smoking (15).
The measurement of weight, blood pressure, and total cholesterol has been described elsewhere (25). The presence of respiratory disease (physical or history of bronchial asthma, pulmonary emphysema, chronic bronchitis, pulmonary tuberculosis, bronchiectasis, pulmonary fibrosis, and thorax deformity) was evaluated at each examination by the examining physician.
Statistical analyses were performed by SPSS for Windows (SPSS, Inc., Chicago, IL). One-way analysis of variance was used to compare the means of age, baseline level of pulmonary function, and baseline duration of smoking in the tertiles of baseline physical activity. Between the tertiles of baseline physical activity, the differences in occupational activity and smoking habits during the follow-up (on the basis of smoking data from 1964–1974) were examined using χ2 analysis.
The effect of potential determinants on the mean annual change in FEV0.75 during 10 years of follow-up was calculated by a linear regression model (n = 429). The main determinant of interest was baseline physical activity; other variables were age, smoking habits, and initial level of pulmonary function. Analysis of covariance analyses were used to describe the differences in the mean annual decline in FEV0.75 between the levels of physical activity with an adjustment for age, initial level of pulmonary function, and smoking habits during the follow-up. The number of men included in the analysis of covariance analyses was 275 between 1964 and 1984 and 186 between 1964 and 1989. For addition, the following additional adjustments were performed. An additional adjustment for occupational activity was performed using a dichotomous variable (sedentary, light, and moderate occupational activity compared with heavy/very heavy occupational activity). An adjustment for tobacco consumption was made using first the baseline duration of smoking as a continuous variable and then the mean of reported cigarette consumption during the follow-up as a secondary continuous variable (for quitters only, the data from those examinations when they reported smoking were used in calculating this variable). An adjustment was also made for the presence of respiratory disease (a dichotomous variable).
The influence of the changes in physical activity over 20 years (1964–1984) on mortality during the subsequent 15 years (1984–1999) was studied by Cox's proportional hazards regression model. The analysis was adjusted for potential confounders (values in 1984), namely, age, height-adjusted FEV0.75, diastolic blood pressure, and total cholesterol as continuous variables, body mass index as a dichotomous variable (less than 20, and 20 or more), and smoking habits as a three-category variable (never-smokers, quitters, and continuous smokers). An additional adjustment for tobacco consumption was performed in the same way as in previous analysis. All deaths between 1984 and 1999 are known, but there were nine men with missing values in the multivariate analyses. Thus, altogether, 266 out of 275 men were included in the mortality analyses, and there were a total of 202 deaths.
The baseline characteristics of study subjects are shown by the tertiles of baseline physical activity in Table 1
Tertile of Physical Activity* | ||||||
---|---|---|---|---|---|---|
Low (n = 143) | Middle (n = 143) | High (n = 143) | p Value | |||
Mean age, yr, SD | 54.3 (5.3) | 54.1 (5.6) | 54.4 (5.4) | 0.843 | ||
Mean FEV0.75, ml, SD | 2,939 (0.571) | 2,939 (0.625) | 2,956 (0.565) | 0.963 | ||
Occupational activity, % | < 0.001 | |||||
Light/moderate | 29.1 | 12.6 | 12.7 | |||
Heavy/very heavy | 70.9 | 87.4 | 87.3 | |||
Smoking category,† % | 0.715 | |||||
Never | 21.7 | 28.7 | 27.3 | |||
Quit‡ | 35.7 | 33.5 | 34.2 | |||
Continuous | 42.6 | 37.8 | 38.5 | |||
Mean duration of smoking, yr, SD | 24.3 (8.4) | 24.1 (9.8) | 22.9 (10.2) | 0.540 |
The linear regression model showed that the annual decline in FEV0.75 increased with smoking, initial pulmonary function, and age during the first 10 years (Table 2)
Regression Coefficient (95% CI) | p Value | |
---|---|---|
Tertile of baseline physical activity* | ||
Middle | −0.8 (−9.9, 8.4) | 0.873 |
High | 9.8 (0.7,19.0) | 0.035 |
Smoking category† | ||
Quit | −13.1 (−22.8, −3.4) | 0.008 |
Continuous | −18.8 (−28.3, −9.3) | < 0.001 |
Age, yr | −2.0 (−2.8, −1.3) | < 0.001 |
Baseline FEV0.75, L | −14.3 (−21.0, −7.6) | < 0.001 |
Intercept | 108.0 (57.9, 158.1) |
Smoking Category | ||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
All | Never | Quit‡ | Continuous | |||||||||||||||||
Tertile of
Physical Activity* | n | Decline†
(ml/yr) | p Value | n | Decline
(ml/yr) | p Value | n | Decline
(ml/yr) | p Value | n | Decline
(ml/yr) | p Value | ||||||||
Low | 98 | −45.2 (−50.1, −40.3) | Reference | 17 | −35.4 (−47.0, −23.8) | Reference | 47 | −46.0 (−53.0, −38.9) | Reference | 34 | −55.6 (−63.8, −47.4) | Reference | ||||||||
Middle | 109 | −39.9 (−44.6, −35.3) | 0.083 | 38 | −27.7 (−35.4, −19.9) | 0.233 | 50 | −44.1 (−50.9, −37.4) | 0.831 | 21 | −46.0 (−56.5, −35.6) | 0.258 | ||||||||
High | 68 | −34.8 (−40.6, −29.0) | 0.009 | 15 | −24.1 (−36.5, −11.6) | 0.063 | 31 | −36.1 (−44.8, −27.5) | 0.124 | 22 | −44.7 (−54.8, −34.5) | 0.162 | ||||||||
p for trend | 275 | 0.006 | 70 | 0.060 | 128 | 0.144 | 77 | 0.139 |
During the follow-up, physical activity associated with a slower decline in FEV0.75 in all smoking categories, and the interaction of the effects of smoking habits and physical activity on FEV0.75 was not significant. However, because of the additive effects of physical activity and nonsmoking, the decline in FEV0.75 in the never-smokers in the highest tertile of physical activity was less than half of that experienced by smokers in the lowest tertile of physical activity (Table 3).
At the baseline, there were no significant differences in FEV0.75 values between the tertiles among those surviving 25 years (n = 186) (Table 4)
Tertile of Physical Activity* | n (n = 186) | Mean Baseline FEV0.75† (ml) | p Value | Decline‡ (ml/yr) | p Value | Mean FEV0.75 after 25 Years§ (ml) | p Value |
---|---|---|---|---|---|---|---|
Low | 80 | 3,014 | Reference | −44.4 (−48.8, −40.1) | Reference | 1,940 | Reference |
Middle | 70 | 3,112 | 0.253 | −40.5 (−45.2, −35.8) | 0.215 | 2,102 | 0.117 |
High | 36 | 3,147 | 0.207 | −36.5 (−42.9, −30.1) | 0.043 | 2,234 | 0.015 |
For trend | 0.201 | 0.035 | 0.012 |
During the follow-up, continued high physical activity and a change in physical activity to a high level are associated with younger age, a slower decline in FEV0.75, and higher FEV0.75 values after 20 years (Table 5)
Physical Activity over 20 Years‡ | |||||||||
---|---|---|---|---|---|---|---|---|---|
Low (Continued) | Decreased to low | Middle (Unchanged or Changed to Middle) | High (Unchanged or Increased to High) | ||||||
(n = 60) | (n = 75) | (n = 88) | (n = 43) | p for Trend | |||||
Decline in FEV0.75 during 20 yrs, ml/yr*, SD | −44.9 (22.7) | −42.5 (29.0) | −37.6 (19.8) | −36.5 (19.7) | 0.029 | ||||
Mean FEV0.75 after 20 yrs, ml, SD† | 2,195 (0.718) | 2,124 (0.695) | 2,355 (0.651) | 2,440 (0.501) | 0.021 | ||||
Mean age after 20 years, yr, SD | 73.4 (5.2) | 74.2 (5.2) | 71.9 (5.1) | 71.4 (4.4) | 0.006 | ||||
Mean activity after 20 years, kJ/day, SD | 416 (152) | 444 (174) | 964 (166) | 2,143 (844) | < 0.001 |

Figure 1. Cumulative survival probability curves for changes in physical activity during the preceding 20 years based on Cox's proportional hazards regression model (adjusted for age, smoking habits, body mass index, diastolic blood pressure, total cholesterol, and pulmonary function). Thin gray line = high (constant or increased to high); thin black line = middle (constant or changed to middle); thick gray line = decreased to low; and thick black line = low (constant).
[More] [Minimize]Our results suggest that physical activity may delay the decline in pulmonary function occurring in middle and old age. The beneficial effect of physical activity on pulmonary function was independent of smoking and was similar in all smoking categories. In our study, the adjusted decline in FEV0.75 was significantly slower among men in the highest tertile of physical activity at the baseline and during the follow-up. The 25-year follow-up was long enough to permit us to carry out long-term comparisons. In agreement with our results, highly fit older subjects have had better pulmonary function (17, 20, 21), and physical activity has been positively associated with pulmonary function (16, 18, 19) in previous cross-sectional studies. In the Amsterdam Growth and Health Study, physical activity was observed to be positively correlated to changes in FVC between ages 13–27 years over a period of 15 years (22). On the other hand, no advantageous effect of physical activity on the decline in resting lung function (29) was found among 18 nonsmoking older athletes in their 60s and 70s during a 6-year follow-up.
In the Harvard Alumni Health Study, those individuals expending 2,000 or more kcal per week in walking, climbing stairs, and playing sports reduced their risk of death by 28% compared with less active men (6). The association of physical activity was strongest for cardiovascular deaths, but the amount of exercise was also inversely related to deaths due to respiratory diseases (6). In our study, energy expenditure of more than 2,268 kcal/week was shown to reduce the decline in pulmonary function (the limit for our highest tertile was 1,361 kJ/day, which is equivalent to a weekly energy expenditure of 7 × 1,361 kJ = 9,527 kJ = 9,527/4.2 kcal = 2,268 kcal). In addition, in this study, those subjects with continued high activity or those who increased their physical activity so that they were entered into the highest tertile had lower all-cause mortality. In the Harvard Alumni Health Study, the subjects who took up moderately vigorous sports activity experienced a substantial reduction in mortality from all causes (30).
Our study subjects lived in a nonpolluted rural area, and most of them were farmers. The measure of physical activity was based on the amount of daily walking, cycling, and skiing measured at the baseline and the amount of daily walking and cycling during the follow-up. We consider that the sum of these activities most probably provides a reasonable estimate of the subjects' physical activity because other types of exercise were uncommon among the men studied (5). The correlation coefficients obtained for the correlations between measured physical activity at each examination point and our calculated average measures were high and thus further support our justification for using mean physical activity variables. The intensity of each activity was not known. However, it might be less variable in this population of rural men than would be detected in more heterogeneous study populations because among the study subjects, physical activities consisted mostly of activities conducted at work or on the way to work. We had different follow-up times on our study subjects. Those subjects seen only initially and during the first 10 years were older and had lower baseline FEV0.75 values than those surviving 20 and 25 years. However, between these groups, there were no differences in relationship to occupational activity, smoking habits, or duration of smoking; therefore, these groups were comparable, and no bias was created in the data in this sense.
The results in this study can be compared with other studies that have used FEV1 because FEV0.75 can be assumed to measure approximately the same as FEV1 (FEV0.75 needs to be multiplied by 1.09 to calculate the FEV1) (31). The estimated mean annual decline in FEV0.75 between examinations could theoretically have been affected by the change in the equipment used to measure FEV0.75 during the follow-up. However, this does not disturb the comparisons between the tertiles of physical activity because all participants were measured using identical equipment at each examination.
A loss of lung elastic recoil, increased chest wall compliance, and a decrease in the strength of respiratory muscles have been proposed to be the most important factors contributing to the decline in pulmonary function with age (32). The loss of elastic recoil can lead to premature airway closure, resulting in air trapping during forced expiration (33). It is possible that physical activity could counteract this stiffening tendency in the chest wall. Older endurance athletes have been shown to suffer less aging-related effects on lung elastic recoil and diffusion surface (34). It has also been claimed that physical activity can enhance inspiratory muscle endurance (18).
In general, the amount of physical activity declines with age (35). According to surveys conducted in Australia, Canada, Finland, and the United States, one-quarter to one-third of the adult population are sedentary in their leisure time (36). However, there is clear evidence that there has been a (modest) increase in the prevalence of exercise (for moderate levels of activity) over at least the past decade (36). Thus, it is possible that more people may be now expected to preserve moderate pulmonary function into old age.
In conclusion, higher physical activity was related to a slower decline in pulmonary function. The physical activities assessed in this study (walking and cycling) can be performed by all individuals. Our study subjects lived in a rural environment, and thus, some caution is needed in interpretation of the results with respect to outdoor exercise in heavily polluted environments. Although smoking cessation is certainly an important way to reduce the decline in pulmonary function in smokers, physical activity appears to be beneficial in both smokers and nonsmokers. These findings are potentially important from a public health and clinical point of view. For example, among chronic obstructive pulmonary disease patients, exercise training could be used to delay the deterioration in pulmonary function.
The authors thank Juha Pekkanen, M.D., Ph.D.
1. | Malbut-Shennan K, Young A. The physiology of physical performance and training in old age. Coron Artery Dis 1999;10:37–42. |
2. | Spina RJ, Turner MJ, Ehsani AA. Exercise training enhances cardiac function in response to afterload stress in older men. Am J Physiol 1997;272:H995–H1000. |
3. | Schulman SP, Fleg JL, Goldberg AP, Busby-Whitehead J, Hagberg JM, O'Connor FC, Gerstenblith G, Becker LC, Katzel LI, Lakatta LE, Lakatta EG. Continuum of cardiovascular performance across a broad range of fitness levels in healthy older men. Circulation 1996;94:359–367. |
4. | Poirier P, Despres JP. Exercise in weight management of obesity. Cardiol Clin 2001;19:459–470. |
5. | Pekkanen J, Marti B, Nissinen A, Tuomilehto J, Punsar S, Karvonen M. Reduction of premature mortality by high physical activity: a 20-year follow-up of middle-aged Finnish men. Lancet 1987;27:1473–1477. |
6. | Paffenbarger RS Jr, Hyde RT, Wing AL, Hsieh C-C. Physical activity, all-cause mortality, and longevity of college alumni. N Engl J Med 1986;314:605–613. |
7. | Leon AS, Connett J, Jakobs DR, Rauramaa R. Leisure-time physical activity levels and risk of coronary heart disease and death. JAMA 1987;258:2388–2395. |
8. | Hakim AA, Petrovitch H, Burchfiel CM, Ross GW, Rodriguez BL, White LR, Yano K, Curb JD, Abbott RD. Effects of walking on mortality among nonsmoking retired men. N Engl J Med 1998;338:94–99. |
9. | Blair SN, Kohl HW, Barlow CE, Paffenbarger RS Jr, Gibbons LW, Macera CA. Changes in physical fitness and all-cause mortality. A prospective study of healthy and unhealthy men. JAMA 1995;273:1093–1098. |
10. | Burrows B, Lebowitz MD, Camilli AE, Knudson RJ. Longitudinal changes in forced expiratory volume in one second in adults: methodologic considerations and findings in healthy nonsmokers. Am Rev Respir Dis 1986;133:974–980. |
11. | Tager IB, Segal MR, Speizer FE, Weiss ST. The natural history of forced expiratory volumes: effect of cigarette smoking and respiratory symptoms. Am Rev Respir Dis 1988;138:837–849. |
12. | Xu X, Dockery DW, Ware JH, Speizer FE, Ferris BG Jr. Effects of cigarette smoking on rate of loss of pulmonary function in adults: a longitudinal assessment. Am Rev Respir Dis 1992;146:1345–1348. |
13. | Burchfiel CM, Marcus EB, Curb JD, Maclean CJ, Vollmer WM, Johnson LR, Fong K-O, Rodriguez BL, Masaki KH, Buist AS. Effects of smoking and smoking cessation on longitudinal decline in pulmonary function. Am J Respir Crit Care Med 1995;151:1778–1785. |
14. | Scanlon PD, Connett JE, Waller LA, Altose MD, Bailey WC, Buist SA, Tashkin DP. Smoking cessation and lung function in mild-to-moderate chronic obstructive pulmonary disease: the Lung Health Study. Am J Respir Crit Care Med 2000;161:381–390. |
15. | Pelkonen M, Notkola I-L, Tukiainen H, Tervahauta M, Tuomilehto J, Nissinen A. Smoking cessation, decline in pulmonary function and total mortality: a 30 year follow up study among the Finnish cohorts of the Seven Countries Study. Thorax 2001;56:703–707. |
16. | Burchfiel CM, Enright PL, Sharp DS, Chyou P-H, Rodriguez BL, Curb JD. Factors associated with variations in pulmonary function among elderly Japanese-American men. Chest 1997;112:87–97. |
17. | Hagberg JM, Yerg JE, Seals DR. Pulmonary function in young and older athletes and untrained men. J Appl Physiol 1988;65:101–105. |
18. | Chen H-I, Kuo C-S. Relationship between respiratory muscle function and age, sex, and other factors. J Appl Physiol 1989;66:943–948. |
19. | Higgins M, Keller JB, Wagenknecht LE, Townsend MC, Sparrow D, Jacobs DR Jr, Hughes G. Pulmonary function and cardiovascular risk factor relationships in black and in white young men and women: the Cardiac Study. Chest 1991;99:315–322. |
20. | Jonhson BD, Reddan WG, Seow KC, Dempsey JA. Mechanical constraints on exercise hyperpnea in a fit aging population. Am Rev Respir Dis 1991;143:968–977. |
21. | Jonhson BD, Reddan WG, Pegelow DF, Seow KC, Dempsey JA. Flow limitation and regulation of functional residual capacity during exercise in a physically active aging population. Am Rev Respir Dis 1991;143:960–967. |
22. | Twisk JW, Staal BJ, Brinkman MN, Kemper HCG, van Mechelen W. Tracking of lung function parameters and the longitudinal relationship with lifestyle. Eur Respir J 1998;12:627–634. |
23. | Jakes RW, Day NE, Patel B, Khaw K-T, Oakes S, Luben R, Welch A, Bingham S, Wareham NJ. Physical inactivity is associated with lower forced expiratory volume in 1 second: European Prospective Investigation into Cancer-Norfolk Prospective Population Study. Am J Epidemiol 2002;156:139–147. |
24. | Karvonen M, Blomqvist G, Kallio V, Orma E, Punsar S, Rautaharju P, Takkunen J, Keys A. Men in rural East and West Finland. Acta Med Scand 1967;460:169–190. |
25. | Keys A. Coronary heart disease in seven countries. Monograph No. 29. Dallas, TX: American Heart Association; 1970. |
26. | Pelkonen M, Tukiainen H, Tervahauta M, Notkola I-L, Kivelä S-L, Salorinne Y, Nissinen A. Pulmonary function, smoking cessation and 30 year mortality in middle aged Finnish men. Thorax 2000;55:746–750. |
27. | Fox SM, Naughton JP, Gorman PA. Physical activity and cardiovascular health: III: The exercise prescription; frequency and type of activity. Mod Concepts Cardiovasc Dis 1972;41:25–30. |
28. | Lakka TA, Venäläinen JM, Rauramaa R, Salonen R, Tuomilehto J, Salonen JT. Relation of leisure-time physical activity and cardiorespiratory fitness to the risk of acute myocardial infarction. N Engl J Med 1994;330:1549–1554. |
29. | McClaran SR, Babcock MA, Pegelow DF, Reddan WG, Dempsey JA. Longitudinal effects of aging on lung function at rest and exercise in healthy active fit elderly adults. J Appl Physiol 1995;78:1957–1968. |
30. | Paffenbarger RS Jr, Hyde RT, Wing AL, Lee I-M, Jung DL, Kampert JB. The association of changes in physical activity level and other lifestyle characteristics with mortality among men. N Engl J Med 1993;328:538–545. |
31. | Cotes JE. Lung function: assessment and application in medicine, 3rd ed. Boston: Blackwell Scientific Publications; 1975. |
32. | Janssens JP, Pache JC, Nicod LP. Physiological changes in respiratory function associated with aging. Eur Respir J 1999;13:197–205. |
33. | Chan ED, Welsh CH. Geriatric respiratory medicine. Chest 1998;114:1704–1733. |
34. | Babcock MA, Dempsey JA. Pulmonary system adaptations: limitations to exercise. In: Bouchard C, Shephard RJ, Stephens T, eds. Physical activity, fitness, and health, 1st ed. Champaign, IL: Human Kinetics Publishers; 1994. p. 320–330. |
35. | Caspersen CJ, Pereira MA, Curran KM. Changes in physical activity patterns in the United States, by sex and cross-sectional age. Med Sci Sports Exerc 2000;32:1601–1609. |
36. | Stephens T, Caspersen CJ. The demography of physical activity. In: Bouchard C, Shephard RJ, Stephens T, eds. Physical activity, fitness, and health, 1st ed. Champaign, IL: Human Kinetics Publishers; 1994. p. 204–213. |