(Circulation. 1999;100:9-13.)
© 1999 American Heart Association, Inc.
Clinical Investigation and Reports |
From the Division of Biostatistics and Epidemiology, University of Virginia School of Medicine, Charlottesville, Va (A.A.H., R.D.A.); the University of Minnesota Medical School, Minneapolis, Minn (A.A.H.); the Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii (J.D.C., H.P., B.L.R., G.W.R., R.D.A.); the Honolulu Heart Program, Kuakini Medical Center, Honolulu, Hawaii (J.D.C., H.P., B.L.R., K.Y., R.D.A.); the Department of Veterans' Affairs, Honolulu, Hawaii (G.W.R.); and the Honolulu-Asia Aging Study, Honolulu, Hawaii (J.D.C., H.P., G.W.R., L.R.W., R.D.A.).
Correspondence to Robert D. Abbott, PhD, Division of Biostatistics and Epidemiology, Box 600, University of Virginia School of Medicine, Charlottesville, VA 22908. E-mail rda3e{at}virginia.edu
| Abstract |
|---|
|
|
|---|
Methods and ResultsFor this study, distance walked (mile/d) was examined at a baseline examination that occurred from 1991 to 1993 in the Honolulu Heart Program. Incident coronary heart disease from all causes was observed over a 2- to 4-year follow-up period. Subjects followed up were 2678 physically capable elderly men aged 71 to 93 years. During the course of follow-up, 109 men developed coronary heart disease. Men who walked <0.25 mile/d had a 2-fold increased risk of coronary heart disease versus those who walked >1.5 mile/d (5.1% versus 2.5%; P<0.01). Men who walked 0.25 to 1.5 mile/d were also at a significantly higher risk of coronary heart disease than men who walked longer distances (4.5% versus 2.5%; P<0.05). Adjustment for age and other risk factors failed to alter these findings.
ConclusionsFindings from the Honolulu Heart Program, which targeted physically capable elderly men, suggest that the risk of coronary heart disease is reduced with increases in distance walked. Combined with evidence that suggests that an active lifestyle reduces the risk of cardiovascular disease in younger and more diverse groups, this suggests that important health benefits could be derived by encouraging the elderly to walk.
Key Words: exercise cardiovascular diseases aging mortality
| Introduction |
|---|
|
|
|---|
| Methods |
|---|
|
|
|---|
Among the series of repeat physical examinations, distance walked
(mile/d) was first assessed at the third examination (1980 to 1982) of
participants who were enrolled in the Cooperative Lipoprotein
Phenotyping Study.7 During that examination, subjects
comprised both a select and random sample of surviving members of the
entire cohort.8 Among those in the random sample, 707 men
were nonsmoking, retired, and physically capable of undertaking
1
hour of slight, moderate, or heavy activity. This is the sample that
was described in a previous report from the Honolulu Heart Program that
showed that walking had a significant effect on reduction in
mortality.4 Information on distance walked was next
collected at an examination that occurred from 1991 to 1993 among 3845
members of the original cohort (
80% of the surviving members who
were originally enrolled in the Honolulu Heart Program).
The present study examined the effects of distance walked on
coronary heart disease morbidity and mortality among men who
participated in the 1991 to 1993 examinations. Only men free of
coronary heart disease (including angina pectoris and
coronary insufficiency) and capable of undertaking
1 hour of
slight, moderate, or heavy activity are considered for follow-up.
Exclusions based on smoking and retirement status were not made because
most men were nonsmokers (93%) and most were retired (95%). Further
comment on these factors will appear later. The final sample considered
for the present study included 2678 men aged 71 to 93 years when
follow-up began.
After the 1991 to 1993 baseline examination, 2 to 4 years of follow-up were available to explore the relationship between distance walked and the risk of coronary heart disease. Herein, coronary heart disease is defined to include unequivocal findings through hospital surveillance of nonfatal myocardial infarction, coronary death, and sudden death within an hour that could not be attributed to another cause. Identification of such events was confirmed by a review of all suspected coronary outcomes by the Honolulu Heart Program Morbidity and Mortality Review Committee. Further description of the definition of coronary heart disease is provided elsewhere.6
To help isolate the independent effect of distance walked on
coronary heart disease, statistical analysis included
adjustments for several possible risk factors that were measured at the
time walking was assessed. Factors included age, total and HDL
cholesterol, hypertension, diabetes, alcohol intake, and
years of childhood lived in Japan. A diagnosis of hypertension was made
when either systolic or diastolic blood pressure
was
140 or 90 mm Hg, respectively, or when a subject was
receiving medication for high blood pressure. Diabetes was defined on
the basis of medical history or the use of insulin or oral hypoglycemic
therapy. On the basis of serum samples collected at the 1991 to 1993
examinations, diabetes was also considered to be present when
fasting glucose concentration exceeded 6.9 mmol/L (125 mg/dL) or
when the nonfasting level was
11.1 mmol/L (200 mg/dL) 2 hours
after ingestion of a 200-g glucose challenge. Further description of
the risk factors is provided elsewhere.5 Effects of
retirement and smoking status on the relationship between walking and
coronary heart disease were also considered.
In addition to the above factors, adjustments were made for a summary measure of physical function based on performance on a battery of tasks that participants were asked to undertake. The battery included tests that measured time to walk 10 feet, ability to walk on toes and heals, hand strength, ability to stand on a chair, and other factors related to physical function. Based on a weighted average of the individual items, a summary measure of physical function was created. The resulting measure is referred to as the performed physical function score. Herein, higher scores represent better physical function than lower scores.
To describe the way in which distance walked might vary with each of the possible confounding characteristics, age-adjusted mean levels of each of the factors were calculated across ranges of distance walked. Procedures for adjustment were based on ANCOVA methods with linear and logistic regression models.9 Proportional hazards regression models10 were used to examine the independent effect of walking on the risk of coronary heart disease and to provide estimates of relative risk among the ranges of distance walked. To determine whether there was a dose-response relationship between distance walked and the risk of coronary heart disease, as has been reported elsewhere for total mortality, cardiovascular disease, and death due to cancer,1 2 3 4 distance walked was also modeled as a continuous variable. The exponential of the resulting regression coefficient, after multiplication by 0.5 mile, was then derived to yield an estimate of the relative risk of coronary heart disease that could be attributed to a 0.5-mile difference in distance walked.11 Other forms of the relationship between distance walked and the risk of coronary heart disease were also considered. All reported probability values were based on 2-sided tests of significance.
| Results |
|---|
|
|
|---|
3 mile/d, whereas 5 of 806 walked as
much as 8 mile/d.
Table 1
shows the unadjusted and
age-adjusted percent incidence of coronary heart disease
according to ranges of distance walked per day based on the 2 to 4
years of follow-up. During this period of time, 109 men experienced a
coronary event. The median time to occurrence of an event was
2.1 years.
|
For men who walked >1.5 mile/d, the unadjusted incidence of
coronary heart disease was 2.5% (20/806). For men who walked
<0.25 mile/d, the incidence was doubled to 5.1% (41/805). Men who
walked >1.5 mile/d had a significantly lower risk of coronary
heart disease than men who walked 0.25 to 1.5 mile/d
(P<0.05) and those who walked shorter distances
(P<0.01). The trend for the risk of coronary heart
disease to decline with increases in distance walked was also
statistically significant when distance walked was modeled as a
continuous variable (P<0.001). Here, the exponential of
the corresponding regression coefficient (ß=-0.334, SE=0.098), after
multiplication by 0.5 mile, yields a relative risk of 0.85 (95% CI,
0.77 to 0.93), suggesting that the risk of coronary heart
disease is reduced by 15% (95% CI, 7% to 23%) for every 0.5-mile
increase in distance walked per day. Adjustment for age did little to
alter this result or other comparisons in Table 1
. More complex
forms of the relationship between distance walked and the risk of
coronary heart disease (such as a quadratic or a threshold
effect) were not apparent or statistically significant.
Table 2
describes how other risk factors
that were determined at the 1991 to 1993 examination were associated
with distance walked. As might be expected, the performed physical
function score increased with increases in distance walked. Men who
walked the longest distances (>1.5 mile/d) had significantly higher
levels of physical function than those who walked less
(P<0.01). Levels of total cholesterol were also
higher in the men who walked the most but only significantly higher
than in men who walked 0.25 to 1.5 mile/d (5.0 versus 4.9 mmol/L
[194 versus 190 mg/dL]; P<0.05). There was no clear
association between distance walked and levels of HDL
cholesterol, the percent of men with diabetes, or childhood
years lived in Japan.
|
The percent of men with hypertension appeared to increase with distance walked, but differences between ranges of distance walked were not statistically significant. No clear pattern appeared to exist between the percent of men who smoked cigarettes and distance walked, although men who walked the most (>1.5 mile/d) were significantly more likely to smoke cigarettes than men who walked the least (<0.25 mile/d; P<0.001) and significantly less likely to smoke cigarettes versus men who walked 0.25 to 1.5 mile/d (P<0.05). Alcohol intake was significantly less in men who walked the most than in men in all other groups of distances walked (P<0.05). Although there were significant differences in the percent of men who were retired among the walking groups, differences were modest.
To help determine whether the risk of coronary heart disease
could be attributed to an association between walking and the other
risk factors, proportional hazards regression models were estimated in
an attempt to control for possible confounding influences that might
involve these factors. Results are shown in Table 3
, with comparisons of the expected risk
of coronary heart disease among the ranges of distance walked
per day.
|
After adjustment for age and other risk factors, the risk of coronary heart disease was 2.3 times greater in men who walked <0.25 mile/d compared with men who walked >1.5 mile/d (P<0.001). The risk of coronary heart disease in men who walked 0.25 to 1.5 mile/d was double the risk in men who walked farther (P<0.05). The difference between men who walked the least (<0.25 mile/d) versus those who walked 0.25 to 1.5 mile/d was not statistically significant. The risk of coronary heart disease decreased with each increase in amount of distance walked (P=0.002). The removal of men who smoked cigarettes or who were not retired failed to alter these results appreciably.
| Discussion |
|---|
|
|
|---|
The present study used a much larger sample of elderly men in whom
coronary heart disease morbidity and mortality is sufficiently
common to allow specific consideration of fatal and nonfatal
coronary events. Given that the average life expectancy for men
of similar age to those in the study sample is
9
years,13 the 2- to 4-year follow-up also
represents a large proportion of available life expectancy. The
data from the Honolulu Heart Program suggest that walking among elderly
men is related to a lower risk of coronary heart disease.
Elderly men who walked >1.5 mile/d were at half the risk of developing
coronary heart disease as men who walked <0.25 mile/d.
As in the previous report from the Honolulu Heart Program, attempts
were made to examine only physically capable men. The exclusion of
those who were not physically capable offers the advantage of
diminishing the possibility that effects of walking on the development
of coronary heart disease could have been achieved through
associations with disability and physical impairment. The exclusion of
men who reported that they did no walking failed to alter the reported
findings. As seen in Table 3
, even in men who walked at least
0.25 mile/d, the beneficial effect of walking on coronary heart
disease persisted. In the present study, men who walked 0.25 to 1.5
mile/d were at a significantly higher risk of coronary heart
disease than men who walked farther.
An additional advantage of studying elderly men in the mild climate of Hawaii is that walking on a continuous basis may be more easily sustained throughout the year. Self-reported activity may also be more consistent with actual behavior, because recall is less likely to be interrupted by long bouts of inclement weather.
Unfortunately, information about the intensity and duration of walking is lacking in the Honolulu Heart Program. This may be less of a drawback in the more homogeneous sample of elderly men in the Honolulu cohort compared with younger groups or in comparisons with samples in which outside activity is often environmentally influenced. Elderly men, particularly those exceeding 70 years of age, would be less likely to undertake vigorous walking as an exercise, and as a result, intensity and duration might be less variable than in more diverse groups. Because most men in the Honolulu sample spent much of their lives in Hawaii (nearly 90% were born in Hawaii), we can speculate that walking in this cohort could reflect a regular and lifelong pattern of behavior as opposed to behaviors that might be more sporadic through migration or because of residence in hostile climates. Although it requires additional study, this might suggest that lifelong behavior may be important in influencing the risk of coronary heart disease as opposed to irregular behavioral patterns. Whether walking can reduce coronary heart disease risk when it is begun later in life in historically sedentary individuals is unclear.
Although the island environment of Hawaii might provide an ideal
setting for the study of outdoor activities such as walking, the
generalization of findings among Japanese-American men to other groups
is important. Unfortunately, only a few studies have examined the
effects of walking on death and cardiovascular disease,
although published reports suggest that the health benefits from
walking that have been observed in the Honolulu Heart Program may also
extend to women and younger men. Investigators from the Harvard Alumni
Study showed that in men aged 35 to 74 years, walking led to a 21%
lower risk of death as distance walked was increased from <0.5 mile to
1.3 mile/d.2 In a recent report from the Nurses Health
Study, women were also observed to benefit from walking through an
association with a reduced risk of cardiovascular
disease.3
Although mechanisms through which walking reduces the risk of death and cardiovascular disease are unknown, presumably such an effect is achieved through a variety of indirect pathways that could influence cardiovascular fitness, hypertension, lipid profiles, clotting factors, and other concomitant risk factors. Although the effect of walking on coronary heart disease was independent of major risk factors that were determined at the time walking was assessed, it may be that men who walk are more resistant to acute risk factor changes or transitions into adverse risk factor states. For example, men without hypertension who walk regularly may be less prone to develop hypertension then similar men who are sedentary.
Statistical adjustment for the reported use of ß-blockers (12.7%), aspirin use on a regular basis (15.6%), and insulin use (1.8%) also did not explain or alter the relationship between distance walked and the risk of coronary heart disease. Associations between distance walked and the use of each of these medications were also not statistically significant.
In addition, triglyceride levels and a parental history of heart disease (7.8%) had no relationship to distance walked, nor did they influence the findings that are reported herein. Although direct measurement of LDL cholesterol levels was not made, its influence through derivation from the Friedewald formula14 was comparable to the influence of total cholesterol.
It would appear that walking may simply reflect an overall healthy lifestyle that includes a variety of behaviors that might be associated with good nutrition and an interest in a generally more active pattern of living. Although the effects of walking on reducing the risk of mortality appear to be constant across levels of total caloric intake, the percent of calories from protein, fat, and carbohydrates, and the percent preference for a Japanese diet,4 a combined attention to nutrition and active lifestyles would seem to be the best way to minimize the risk of cardiovascular disease.15
Even if walking does not have an independent effect on coronary heart disease, its potential effect through unknown indirect pathways makes it worthy of promotion as a behavior that can prevent or delay the onset of disease. This is especially important because regular walking may be more easily adopted and adhered to in the elderly than more vigorous and stressful exercise. Combined with evidence that suggests that active lifestyles reduce the risk of cardiovascular disease and other adverse outcomes in younger and more diverse groups, this suggests that encouraging the physically capable elderly person to walk and to become active could have important health benefits. It seems prudent that such encouragement should be given as early in life as possible, when good habits are more easily developed.
| Acknowledgments |
|---|
Received March 5, 1999; revision received April 9, 1999; accepted April 15, 1999.
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
E. A. Beverly and L. A. Wray The role of collective efficacy in exercise adherence: a qualitative study of spousal support and Type 2 diabetes management Health Educ. Res., June 16, 2008; (2008) cyn032v1. [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] |
||||
![]() |
J. E Berlin, K. L Storti, and J. S Brach Using Activity Monitors to Measure Physical Activity in Free-Living Conditions Physical Therapy, August 1, 2006; 86(8): 1137 - 1145. [Full Text] [PDF] |
||||
![]() |
K. J. STEWART Physical Activity and Aging Ann. N.Y. Acad. Sci., December 1, 2005; 1055(1): 193 - 206. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Noda, H. Iso, H. Toyoshima, C. Date, A. Yamamoto, S. Kikuchi, A. Koizumi, T. Kondo, Y. Watanabe, Y. Wada, et al. Walking and Sports Participation and Mortality From Coronary Heart Disease and Stroke J. Am. Coll. Cardiol., November 1, 2005; 46(9): 1761 - 1767. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. S. Bassuk and J. E. Manson Epidemiological evidence for the role of physical activity in reducing risk of type 2 diabetes and cardiovascular disease J Appl Physiol, September 1, 2005; 99(3): 1193 - 1204. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. R. Holman Is It Ever Too Late? DOC News, July 1, 2005; 2(7): 10 - 11. [Full Text] |
||||
![]() |
R. J. Petrella, C. N. Lattanzio, A. Demeray, V. Varallo, and R. Blore Can Adoption of Regular Exercise Later in Life Prevent Metabolic Risk for Cardiovascular Disease? Diabetes Care, March 1, 2005; 28(3): 694 - 701. [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] |
||||
![]() |
R. D. Abbott, L. R. White, G. W. Ross, K. H. Masaki, J. D. Curb, and H. Petrovitch Walking and Dementia in Physically Capable Elderly Men JAMA, September 22, 2004; 292(12): 1447 - 1453. [Abstract] [Full Text] [PDF] |
||||
![]() |
N. A. Allen Social Cognitive Theory in Diabetes Exercise Research: An Integrative Literature Review The Diabetes Educator, September 1, 2004; 30(5): 805 - 819. [PDF] |
||||
![]() |
I. Tsuji, K. Takahashi, Y. Nishino, T. Ohkubo, S. Kuriyama, Y. Watanabe, Y. Anzai, Y. Tsubono, and S. Hisamichi Impact of walking upon medical care expenditure in Japan: the Ohsaki Cohort Study Int. J. Epidemiol., October 1, 2003; 32(5): 809 - 814. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. B. Hu and J. E. Manson Walking: The Best Medicine for Diabetes? Arch Intern Med, June 23, 2003; 163(12): 1397 - 1398. [Full Text] [PDF] |
||||
![]() |
R J Shephard and A Vuillemin Limits to the measurement of habitual physical activity by questionnaires * Commentary Br. J. Sports Med., June 1, 2003; 37(3): 197 - 206. [Abstract] [Full Text] [PDF] |
||||
![]() |
V. Press, I. Freestone, and C.F. George Physical activity: the evidence of benefit in the prevention of coronary heart disease QJM, April 1, 2003; 96(4): 245 - 251. [Full Text] [PDF] |
||||
![]() |
M. Tanasescu, M. F. Leitzmann, E. B. Rimm, W. C. Willett, M. J. Stampfer, and F. B. Hu Exercise Type and Intensity in Relation to Coronary Heart Disease in Men JAMA, October 23, 2002; 288(16): 1994 - 2000. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. GLICK Screening for traditional risk factors for cardiovascular disease: A review for oral health care providers J Am Dent Assoc, March 1, 2002; 133(3): 291 - 300. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. E. LIPSHULTZ, S. D. FISHER, W. W. LAI, and T. L. MILLER Cardiovascular Monitoring and Therapy for HIV-Infected Patients Ann. N.Y. Acad. Sci., November 1, 2001; 946(1): 236 - 273. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Abete, N. Ferrara, F. Cacciatore, E. Sagnelli, M. Manzi, V. Carnovale, C. Calabrese, D. de Santis, G. Testa, G. Longobardi, et al. High level of physical activity preserves the cardioprotective effect of preinfarction angina in elderly patients J. Am. Coll. Cardiol., November 1, 2001; 38(5): 1357 - 1365. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. E Hardman Physical activity and health: current issues and research needs Int. J. Epidemiol., October 1, 2001; 30(5): 1193 - 1197. [Full Text] [PDF] |
||||
![]() |
K. Yaffe, D. Barnes, M. Nevitt, L.-Y. Lui, and K. Covinsky A Prospective Study of Physical Activity and Cognitive Decline in Elderly Women: Women Who Walk Arch Intern Med, July 23, 2001; 161(14): 1703 - 1708. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Ashley, A. Lloyd, S. Lamb, and H. Bartlett Is health-related quality of life a suitable outcome measure for evaluating health promotion programmes? Journal of Research in Nursing, May 1, 2001; 6(3): 671 - 678. [Abstract] [PDF] |
||||
![]() |
S. G. Wannamethee, A. G. Shaper, and M. Walker Physical Activity and Mortality in Older Men With Diagnosed Coronary Heart Disease Circulation, September 19, 2000; 102(12): 1358 - 1363. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. M. Gill, L. DiPietro, and H. M. Krumholz Role of Exercise Stress Testing and Safety Monitoring for Older Persons Starting an Exercise Program JAMA, July 19, 2000; 284(3): 342 - 349. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Gaenzer, W. Sturm, and G. Neumayr Effects of Walking on Coronary Heart Disease in Elderly Men Circulation, July 11, 2000; 102 (2): e16 - e16. [Full Text] [PDF] |
||||
![]() |
S. Taddei, F. Galetta, A. Virdis, L. Ghiadoni, G. Salvetti, F. Franzoni, C. Giusti, and A. Salvetti Physical Activity Prevents Age-Related Impairment in Nitric Oxide Availability in Elderly Athletes Circulation, June 27, 2000; 101(25): 2896 - 2901. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. B. Hu, M. J. Stampfer, G. A. Colditz, A. Ascherio, K. M. Rexrode, W. C. Willett, and J. E. Manson Physical Activity and Risk of Stroke in Women JAMA, June 14, 2000; 283(22): 2961 - 2967. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Y. Goraya, S. J. Jacobsen, P. A. Pellikka, T. D. Miller, A. Khan, S. A. Weston, B. J. Gersh, and V. L. Roger Prognostic Value of Treadmill Exercise Testing in Elderly Persons Ann Intern Med, June 6, 2000; 132(11): 862 - 870. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. S Pescatello and J. L VanHeest Physical activity mediates a healthier body weight in the presence of obesity Br. J. Sports Med., April 1, 2000; 34(2): 86 - 93. [Full Text] [PDF] |
||||
![]() |
Walking and Reduced Coronary Mortality in Elderly Men Journal Watch (General), July 23, 1999; 1999(723): 3 - 3. [Full Text] |
||||
![]() |
P. G. Snell and J. H. Mitchell Physical Inactivity : An Easily Modified Risk Factor? Circulation, July 6, 1999; 100(1): 2 - 4. [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||