From Medical Center of Health Science, Toranomon Hospital, Tokyo (S.D.H.,
H.Y.); Department of Public Health, Juntendo University, Tokyo (T.M.); and
Department of Public Health, National Defense Medical College, Saitama (Y.S.),
Japan.
Methods and Results—The study included 3331 adult Japanese men in
whom health benefits, especially CHD risk factors, were compared among
those who were sedentary and those who were engaged in continuous
physical activity of 30 minutes or more per day for 1, 2 and
Conclusions—Those who engaged in regular physical activity
Measurement
The criteria for determining the sum of risk factor scores for
hypertension, abnormal glucose tolerance,
hypertriglyceridemia,
hypercholesterolemia, and low HDL
cholesterol level (one point for each if present) are
shown in Table 2
Statistical Analysis
CHD Risk Factor Values and Physical Activity
Sum of CHD Risk Factor Scores and Physical Activity
Smoking Rate and Physical Activity
Correlations and Multiple Regression Analysis for the
Frequency of Physical Activity and Smoking Status With HDL
Cholesterol Value
Prevalence of Fatty Liver and Physical Activity
CHD risk factors were lowest in the group with regular physical
activity
It is interesting that the smoking rate was also lower in all the
physically active groups. Both smoking status and the frequency of
physical activity were independently associated with the HDL
cholesterol level. However, it is difficult to ascertain
whether the lower smoking rate in the physically active groups is due
to smoking cessation after physical activity for the reduction of
nicotine dependence or an overall greater concern with health on the
part of the physically active subjects compared with the sedentary
subjects. A prospective study is necessary to explore this issue.
The Japanese government encourages employees to receive annual health
examinations for prevention and early diagnosis of disease. Subjects
who undergo periodic health examinations do so voluntarily and may be
more concerned with health than those who do not undergo such
examinations. However, most of those who undergo health examinations
are sedentary. Therefore, it is important to encourage these
individuals to increase their physical activities, reminding them that
"a little physical activity is better than none, and, to a degree,
more is better than less"16 in reducing
CHD risk factors and improving general health.
Received May 21, 1997;
revision received October 23, 1997;
accepted October 27, 1997.
© 1998 American Heart Association, Inc.
Clinical Investigation and Reports
Regular Physical Activity and Coronary Risk Factors in Japanese Men
Abstract
Top
Abstract
Introduction
Methods
Results
Discussion
References
Background—Physical activity
decreases the risk of coronary heart disease (CHD), but its
effects on risk factors require further exploration. 
3 days
per week. Significantly higher HDL cholesterol values;
lower triceps, scapula, and iliac subcutaneous fat thickness; and lower
smoking rates were noted in all physically active groups compared with
the sedentary group, whereas body mass index did not differ
significantly. Waist-to-height ratios and the prevalence of fatty liver
were significantly lower in the groups who exercised 2 or 3 days per
week than in the sedentary group. The lowest triglyceride
values were noted in the group who exercised 3 days per week.
Multiple regression analysis revealed both the frequency of
physical activity and smoking status to be independent positive and
negative factors, respectively, for the HDL cholesterol
value. The sum of the risk factor scores for hypertension, abnormal
glucose tolerance, hypertriglyceridemia,
hypercholesterolemia, and low HDL
cholesterol level (one point for each if present) was
highest in the sedentary group (1.38, 1.19, 1.19, 0.99 for the
sedentary group and the groups who exercised 1, 2, and 3 days per
week). 3
days per week appeared to have the fewest coronary risk
factors. However, even those engaged in physical activity once per week
had fewer CHD risk factors than sedentary individuals.
Key Words: exercise • risk factors • obesity
Introduction
Top
Abstract
Introduction
Methods
Results
Discussion
References
Mortality caused by
coronary heart disease (CHD) was reported to be inversely
related to the level of physical activity and to be reduced in subjects
who exercise regularly.1 2 There are reports
indicating that physical training done less frequently than 2 days per
week generally produces no meaningful change in
VO2max.3 4
Therefore, the Centers for Disease Control and Prevention and the
American College of Sports Medicine recommend 30 minutes or more of
moderate-intensity physical activity on most, preferably all, days of
the week on the basis of documented improvements in fitness, with these
recommendations probably also providing most of the disease prevention
benefits associated with an increase in physical
activity.5 However, some reports suggest
that even a single session of moderate- to long-duration exercise can
reduce blood pressure, glucose, and triglyceride levels and
can increase HDL cholesterol
levels.6 7 8 9 Furthermore, physical activity
has been proposed as an important adjunct in the prevention and
treatment of obesity10 and stress-induced
disorders.11 To further explore the health
benefits related to the frequency of physical activity, we compared CHD
risk factors, including blood pressure, lipids, glucose levels,
obesity, and smoking status, among sedentary subjects and those engaged
in regular physical activity 1, 2, and 3 days per week.
Methods
Top
Abstract
Introduction
Methods
Results
Discussion
References
Subjects and Data Collection
The subjects were 3331 adult Japanese men (age, 48.3±8.4 years
[mean±SD]) who underwent routine health examinations at
Toranomon Hospital between April 1994 and March 1995 for early
detection of disease. Most were government employees and office
workers. The basic survey questions included, " How often do you
engage in regular physical activity lasting 30 minutes or more?"
"What kind of regular physical activity do you do?" And "What is
your present smoking status?" Subjects were classified into the
sedentary group if they did not engage in regular physical activity at
least once per week. They were divided into four groups according to
the replies, ie, sedentary and those engaged in regular physical
activity 1, 2, or 3 days per week. The subject numbers and the ages
of the four groups are shown in Table 1
.
There was no significant difference in age among the sedentary and
physically active groups. The sedentary group accounted for most of the
subjects (72%). Tennis (26.4%) and jogging (21.3%) were the most
frequent activities in the physically active groups.
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Table 1. Subject Numbers and Ages of the Four Groups
Waist circumference was measured at the umbilical level with the
subjects standing and breathing normally, and the waist-to-height ratio
was calculated as an index of abdominal
obesity.12 13 14 The subcutaneous fat
thickness was measured at the middle of the posterior portion of the
upper arm for the triceps area, at the inner margin of the lower end of
the scapula for the scapula area, and near the umbilicus and the upper
margin of the ilium for abdominal areas by the skin-fold caliper
method. Blood was drawn from subjects in the fasted state. Blood
glucose, serum triglyceride, cholesterol, and
HDL cholesterol levels were measured by enzymatic methods,
and hemoglobin A1c
(HbA1c) was assessed by
high-performance liquid chromatography. Fatty
liver was diagnosed by echography. . The
HbA1c level of 6.1% is based on the
mean+SD HbA1c of individuals with normal
oral glucose tolerance test results.
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Table 2. Criteria for Determining the Sum of CHD Risk Factor
Scores
Probabilities of significant differences were compared by
one-way ANOVA and the Tukey-Kramer honestly-significance-difference
test for quantitative variables and by the
2 test for proportions. Correlations and
multiple regression analysis for the frequencies of physical
activity, smoking status, and HDL cholesterol values were
also studied.
Results
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Abstract
Introduction
Methods
Results
Discussion
References
Obesity Indexes and Physical Activity
Comparisons of various obesity indexes among the sedentary and
physically active groups are shown in Table 3. There were significant differences
across the groups except in body mass index (BMI). Significantly lower
subcutaneous fat thickness was noted in the triceps, scapula, and iliac
areas in the physically active groups compared with the sedentary
group. On the other hand, significantly lower waist-to-height ratios
and subcutaneous fat thickness near the umbilicus were noted in those
who engaged in physical activity 2 or 3 days per week compared with
the sedentary group. In addition, waist-to-height ratios and
subcutaneous fat thickness at the scapula and near the umbilicus were
also significantly lower in those who engaged in physical activity 3
days per week than in those who engaged in physical activity only once
per week.
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Table 3. Obesity Indexes and Physical Activity
Comparisons of CHD risk factor values among sedentary and
physically active groups are shown in Table 4. There were significant differences
across the groups for triglyceride and HDL
cholesterol values but not for other risk factor values.
Triglyceride values were significantly lower in the group
engaged in physical activity 3 days per week than in any other group.
On the other hand, HDL cholesterol values were
significantly higher in all physically active groups than in the
sedentary group.
View this table:
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Table 4. CHD Risk Factor Values and Physical Activity
The sum of CHD risk factor scores differed significantly across
the groups. It was significantly higher in the sedentary group than in
any of the physically active groups (Fig 1).
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Figure 1. Sum of coronary heart disease (CHD) risk
factor scores and physical activity (mean±SE; P<.0001
for overall difference; P<.05 for sedentary vs any of
the other physically active groups).
The smoking rate differed significantly across the groups, being
significantly higher in the sedentary than in any of the physically
active groups (Fig 2).
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Figure 2. Smoking rate and physical activity
(P<.0001 for overall difference; P<.05
for sedentary vs any of the other physically active groups).
The frequency of physical activity correlated positively and
present smoking status correlated negatively with the HDL
cholesterol value. Multiple regression analysis
revealed both the frequency of physical activity and smoking status to
be independent positive and negative factors, respectively, affecting
the HDL cholesterol value (Table 5).
View this table:
[in a new window]
Table 5. Correlations and Multiple Regression
Analysis for the Frequencies of Physical Activity and Smoking
Status with HDL Cholesterol Value
There were significant differences across the groups in the
prevalence of fatty liver. The prevalence of fatty liver was
significantly higher in the sedentary group than in the groups who
engaged in physical activity 2 or 3 days per week and in those
engaged in physical activity only once per week compared with those who
exercised 3 days per week group (Fig 3).
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Figure 3. Prevalence of fatty liver and physical activity.
(P<.0001 for overall difference; P<.05
for sedentary vs the group engaged in physical activity 2 days per
week, sedentary group vs the group engaged in physical activity 3
days per week, and group engaged in physical activity once per week vs
that engaged in physical activity 3 days per week).
Discussion
Top
Abstract
Introduction
Methods
Results
Discussion
References
Physical inactivity is prevalent among American adults. In 1991,
54% of American adults reported little or no regular leisure physical
activity.15 Likewise, we found that more
than 72% of adult Japanese men (mostly white-collar workers) are
sedentary even during their leisure time. Although physical activity
favorably modifies CHD risk factors, the frequency of physical activity
needed to accomplish these goals remains poorly defined and
controversial.15 Our results confirm the
public health message that "doing some physical activity is better
than doing none at all."16 Even the
subjects who engaged in regular physical activity once a week had less
subcutaneous fat and higher serum HDL cholesterol levels
than the sedentary individuals. The subjects with a higher frequency of
physical activity showed a further lowering of CHD risk factors and
abdominal obesity and a lower prevalence of fatty liver, although BMI
did not differ. The accuracy of BMI in defining obesity has been
questioned because of the disparity between BMI and body
fat17 in that BMI reflects muscle and bone
as well as fat. The physically active groups might increase their
muscle amount accompanied by loss of fat so that their BMIs would not
be different from that of the sedentary group. On the other hand,
prevention of fatty liver with exercise in rats has been
reported.18 Our study in humans also
indicated a reduced prevalence of fatty liver in the groups engaged in
physical activity 2 or 3 days per week. 3 days per week. Our data support the recommendation of the
American College of Sports Medicine4 and
suggest that the frequency of training is an important determinant of
maximal health benefits on the basis of not only cardiorespiratory
fitness but also CHD risk factors.
Acknowledgments
We thank Mitsui Petrochemical Industries, LTD, for financial
assistance in this study. We also thank Reiko Terada for her
secretarial assistance in the preparation of this manuscript.
Footnotes
Reprints requests to Dr Shiun Dong Hsieh, Medical Center of Health Science, Toranomon Hospital, Toranomon 2–2-2, Minatou-ku, Tokyo 105, Japan.
References
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Abstract
Introduction
Methods
Results
Discussion
References
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