Relation between cigarette smoking and ventilatory threshold in the Japanese
Environ Health Prev Med
Relation between cigarette smoking and ventilatory threshold in the Japanese
Nobuyuki Miyatake 0 1 2 3 4
Takeyuki Numata 0 1 2 3 4
Kenji Nishii 0 1 2 3 4
Noriko Sakano 0 1 2 3 4
Takeshi Suzue 0 1 2 3 4
Tomohiro Hirao 0 1 2 3 4
Motohiko Miyachi 0 1 2 3 4
Izumi Tabata 0 1 2 3 4
0 K. Nishii Okayama Health Foundation Hospital , Okayama Health Foundation, Okayama 700-0952 , Japan
1 T. Numata Okayama Southern Institute of Health , Okayama Health Foundation, Okayama 700-0952 , Japan
2 N. Miyatake (&) N. Sakano Department of Hygiene, Faculty of Medicine, Kagawa University , 1750-1, Miki, Kagawa 761-0793 , Japan
3 M. Miyachi I. Tabata National Institute of Health and Nutrition, Shinjuku , Tokyo 162-8636 , Japan
4 T. Suzue T. Hirao Department of Public Health, Faculty of Medicine, Kagawa University , Kagawa 761-0793 , Japan
The link between cigarette smoking and ventilatory threshold (VT) was investigated. We used data for 407 men and 418 women not taking medication. Habits of cigarette smoking were obtained through interviews by well-trained staff. The influence of cigarette smoking on oxygen uptake, work rate, and heart rate at VT was evaluated. Oxygen uptake at VT in women and work rate at VT in men with cigarette smoking were significantly lower than in subjects without cigarette smoking after adjusting for age. The differences of parameters at VT did not reach significant levels after adjusting for age and exercise habits in both sexes. However, in women without exercise habits, there was significant difference of oxygen uptake at VT between women with and without cigarette smoking after adjusting for age [cigarette smoking (?): 11.5 ± 1.8 ml/ kg/min, cigarette smoking (-): 12.4 ± 2.1 ml/kg/min, p = 0.0006]. The number of cigarettes smoked per day and the Brinkman Index were not clearly correlated with oxygen uptake at VT. A combination of promoting exercise habits and prohibiting cigarette smoking might be recommended for improving the aerobic exercise level, especially in women.
Cigarette smoking; Oxygen uptake; Exercise habits; Ventilatory threshold
Introduction
Cigarette smoking has become an important public health
challenge, and it has been reported that 39.4% of men and
11.0% of women are current smokers in Japan [
1
].
Cigarette smoking is also a strong risk factor for atherosclerosis
and cardiovascular disease in a dose-dependent manner [
2
].
Exercise is considered as a useful method for preventing
and improving atherosclerosis and cardiovascular disease.
The ventilatory threshold (VT) is defined as the upper limit
of aerobic exercise and is thought to serve as an accurate
and reliable standard for exercise prescription [
3
]. Since the
exercise intensity at VT is not harmful to cardiovascular
function, it can be safely applied to patients with
myocardial infarction as an exercise prescription [
4
]. We have
previously reported that aerobic exercise level was
significantly lower in subjects with metabolic syndrome than that
in subjects without the syndrome [
5
], and the prevalence of
metabolic syndrome was significantly higher in subjects
with cigarette smoking than that in subjects without
cigarette smoking [
6
]. However, the relationship between
cigarette smoking and aerobic exercise level defined by VT is
not fully discussed.
The aim of this study is to explore the link between
cigarette smoking and VT in the Japanese population.
Subjects and methods
Subjects
We used data for 407 Japanese men (aged 42.1 ± 11.4 years)
and 418 women (aged 44.8 ± 12.0 years) (5.8%),
retrospectively from a database of 14,345 subjects who met the
following criteria: they had (1) wanted to change their
lifestyle, i.e., diet and exercise habits, and had received an
annual health checkup from June 1997 to May 2007 at
Okayama Southern Institute of Health, (2) they had received
anthropometric and oxygen uptake at VT measurements and
evaluation of cigarette smoking as part of the annual health
checkup, (3) received no medications for diabetes,
hypertension, and/or dyslipidemia, and (4) provided written
informed consent (Table 1).
Ethical approval for the study was obtained from the
Ethical Committee of Okayama Health Foundation.
Anthropometric measurements
Anthropometric and body compositions were evaluated
based on the following parameters: height, body weight,
abdominal circumference, and hip circumference.
Abdominal circumference was measured at the umbilical level, and
the hip was measured at the widest circumference over the
trochanter in standing subjects after normal exhalation [
7
].
Cigarette smoking
The data on cigarette smoking were obtained at interviews by
well-trained staff in a structured way. The subjects were asked
if they currently smoked cigarettes. When the answer was
‘‘yes,’’ they were classified as current smokers and further
questions were asked regarding the average number of
cigarettes smoked per day and their age at starting smoking. When
the answ (...truncated)