Vol.3, No.5, 271-275 (2011)
opyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
A study of fatigue status in Chinese adolescents in an
urban city, Jixi
Ning Zou1, Masaru Kubota1*, A yako Nagai1, Ri Ji Jin2, Shu Xian Liu2
1Department of Human Life and Environment, Nara Women’s University, Nara, Japan;
*Corresponding Author: masaru_kubota@chime.ocn.ne.jp
2Department of Pediatrics, Jixi Mining Group Hospital, Jixi, China.
Received 22 March 2011; revised 20 April 2011; accepted 27 April 2011.
The aim of the study was to clarify the charac-
teristics of fatigue status in Chinese adoles-
cent s. 1018 adolescent s (490 males, 528 females)
aged 12 or 15 years in Jixi city were enrolled.
Between May and September 2009, fatigue
status was investigated using a questionnaire
devised by ourselves, which consisted of 4
physical and 4 mental fatigue items. These
questions were scored from 0 to 3 based on the
frequency of an item occurring, given as the
average of the past one month, and the fatigue
scores were calcu lated. Lifesty l e issue s such as
daily sleep duration, feeling of refreshment in
the morning after wake-up, extracurricular sports
activity, and breakfast intake, and a physical
examination such as height, weight, and waist
circumference were also investigated. Physical
and mental fatigue scores were significantly
higher in subjects aged 15 yrs old than in those
aged 12 years old in both genders. These
scores in females were significantly higher than
those in males at the age of 15 years. Multivari-
ate regression analysis showed that total
(physical plus mental) fatigue scores were as-
sociated with female gender and various life-
styles such as unrefreshed wake-up feeling,
poor extracurricular sports activity, and more
frequent skipping of breakfast. However, body
mass index and waist circumference were not
associated with total fatigue scores.
Keywords: Adolescent; Chinese; Lifestyle; Mental
Fatigue; Physical Fatigue
At present, fatigue is a common social problem both
in adults and in children, especially in developed coun-
tries [1]. Among several types of fatigue, chronic fatigue
syndrome (CFS), defined by intractable physical and
mental fatigue lasting more than 6 months with a num-
ber of accompanying symptoms, has been most vigor-
ously investigated [2,3]. According to several previous
surveys, the prevalence of CFS was estimated to be less
than 3.0% in adults [4-6] and less than 0.5% in adoles-
cents [7-10]. Recently, increasing attention has been paid
to fatigue other than CFS in the community of healthy
adolescents and children, because fatigue may some-
times disturb their daily activities [11]. Fatigue is also
known to be associated with symptoms of depression or
anxiety and a risk factor for the future occurrence of
CFS [12,13]. The prevalence of persistent fatigue in
healthy adolescents has been well investigated in west-
ern countries [8-10,12,13], however, the reported preva-
lence has differed widely among studies due to different
study designs. On the other hand, there have been no
large-scale cohort studies about the actual conditions of
fatigue, as far as we know, in healthy Chinese adoles-
cents. This fact led us to investigate the present fatigue
status in healthy Chinese adolescents, especially in rela-
tion to their lifestyle.
2.1. Subjects
This study was carried out in Jixi city from May to
September in 2009 using 1018 participants. Jixi is a
middle class urban city locating in north China with the
population of 2 million (2000 census). Enrolled in the
present study were 520 students in the 6th grade of ele-
mentary school (12 years) and 498 students in the 3rd
grade of junior high school (15 years). There were 490
males and 528 females. Physicians at Jixi Mining Group
Hospital performed a physical examination that included
height, weight, and waist circumference. Waist circum-
N. Zou et al. / Health 3 (2011) 271-275
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
ference was measured at the navel with the subject at the
erect position after relaxed breathing. Body mass index
(BMI) was calculated by the formula, weight (kg) ÷
height (m)2. Physician asked the participants about their
fatigue status and lifestyles on average over the past one
month. We obtained consent for study participation from
all students beforehand to use their data in our study.
This project was approved by the ethical and epidemi-
ological committee at Nara Women’s University.
2.2. Questionnaire
We devised our own questionnaire about the fatigue
status of the participants. We examined the reliability
and validity of our questionnaire using Japanese adoles-
cents at almost similar age to those in the present study.
In that investigation, greater than 7.0 of Crohnbach’s αs,
and the construct validity of 0.85 in comparison with
Chalder’s scale [14] verified these issues. There were 4
items each on physical and mental fatigue as depicted in
the Appendix. Each item was scored from 0 to 3 (0, not
at all; 1, a few times per month; 2, a few times per week;
3, almost every day). The scores obtained by the physi-
cians were then summed to calculate physical and men-
tal fatigue scores separately (range: 0 - 12). Questions
about lifestyle were: 1) daily sleep duration, 2) feeling of
refreshment in the morning after wake-up (excellent,
score 0: fair, score 1: poor, score 2) 3) extracurricular
sports activity (daily, score 0: sometimes a week, score 1:
rarely, score 2), and 4) breakfast intake (daily, score 0:
sometimes a week, score 1: rarely, score 2).
2.3 Statistics
Differences in mean physical, mental, and total
(physical plus mental fatigue) fatigue scores according
to gender and age were examined by Student’s t test. The
association of total fatigue scores with various lifestyle
elements, BMI, and waist circumference was evaluated
by multivariate regression analysis. A statistical analysis
was made by “StatMate IV” (ATMS, Tokyo, Japan). P
values less than 0.05 were considered significant.
3.1. Factor Anal ysis of the Instrument
In order to determine the factor structures of the ques-
tionnaire, we have done a factor analysis using an
oblique rotation (Promax method). As indicated in Table
1, two dimensions termed as physical and mental fatigue
were extracted. In addition, Crohnbach’s αs were 0.72,
0.74 and 0.79 for physical, mental, and total fatigue
scores, respectively. This fact demonstrates the good
internal consistency of our questionnaire. The coefficient
of factors after the oblique rotation was 0.752.
3.2. Physical Fatigue and Mental Fatigue
Scores in Relation to Age and Gender
Table 2 indicates subject numbers according to age
and gender. The mean and 95% confidence interval (CI)
of physical, mental, and total fatigue scores for different
ages and gender are also shown in Table 2. These scores
at 15 yrs of age were significantly higher than those at
12 yrs of age in both genders (p < 0.01). Female gender
showed higher physical (p < 0.01), mental (p < 0.05),
and total (p < 0.01) fatigue scores only at 15 yrs of age.
Among 8 fatigue items, “to feel a lack of concentration”
was chosen most frequently, followed by “to feel often
tired” and “to feel like lying down”. On the other hand,
“to feel anxious about health” was chosen least fre-
quently (Data not shown).
3.3. Association of Total Fatigue Scores
with Demographic Factors, Lifestyle,
BMI or Waist Circumference
We performed multivariate regression analysis to in-
vestigate the association between total fatigue scores and
demographic factors, lifestyles, BMI or waist circum-
ference. As shown in Table 3, female gender, age, unre-
freshed wake-up feeling, poor extracurricular sports ac-
tivity, and breakfast skipping demonstrated significant
association with an increase of the total fatigue score.
Although statistically not significant, subjects with
shorter daily sleep duration tended to have higher total
fatigue scores. BMI and waist circumference did not
show any significant association.
In healthy adolescents, persistent fatigue that does not
Table 1. Factor analysis of the fatigue questionnaire used in the
present study.
Physical Fatigue Mental Fatigue
1. Often Tired 0.606 0.086
2. Still Tired after Night’s Sleep 0.544 0.095
3. Want to Lie down 0.523 0.072
4. Feel Forceless 0.451 0.159
5. Anxious about the Body 0.052 0.456
6. Lack of Concentration 0.229 0.325
7. Sleepy in the Daytime 0.251 0.301
8. Depressed 0.107 0.431
N. Zou et al. / Health 3 (2011) 271-275
Copyright © 2011 SciRes. http://www.scirp.org/journal/HEALTH/Openly accessible at
Table 2. Fatigue scores according to age, gender, and subject numbers.
Age Gender Number Physical Fatigue ScoreMental Fatigue Score Total Score
Total 520 2.3 [2.1 - 2.5]† 2.1 [2.0 - 2.3] 4.5 [4.1 - 4.8]
Male 227 2.3 [1.9 - 2.6] 2.1 [1.9 - 2.4] 4.4 [3.9 - 4.9] 12 years
Female 293 2.2 [1.9 - 2.4] 2.4 [2.1 - 2.6] 4.5 [4.1 - 4.9]
Total 498 3.6 [3.3 - 3.8] 4.0 [3.8 - 4.2] 7.6 [7.2 - 8.0]
Male 263 3.3 [2.9 - 3.7]** 3.8 [3.5 - 4.1]* 7.1 [6.5 - 7.7]** 15 years
Female 235 3.8 [3.5 - 4.2] 4.3 [4.0 - 4.6] 8.1 [7.6 - 8.8]
Total 1018 2.9 [2.8 - 3.1] 3.1 [2.9 - 3.2] 6.0 [5.7 - 6.3]
Male 490 2.8 [2.6 - 3.1] 3.0 [2.8 - 3.2] 5.8 [5.4 - 6.3] 12 + 15 years
Female 528 3.0 [2.8 - 3.2] 3.1 [2.9 - 3.3] 6.1 [5.7 - 6.5]
†Mean and 95% CI in parentheses are shown; Differences between males and females at each age are: *p < 0.05, **p < 0.01, no
marks, not significant.
Table 3. Multivariate analysis between fatigue score and demographic or lifestyle factors.
Number Coefficient 95% CI p value
Total 1018
Sex 0.89 0.38 - 1.41 < 0.001
Male 490 (48.1)*
Female 528 (51.9)
Age 0.59 0.42 - 0.77 < 0.001
12 years 520 (51.1)
15 years 490 (48.9)
Sleep (Hours/Day) 7.0[7.0 - 7.2]† –0.25 –0.52 - 0.01 0.066
Refreshing after Sleep 2.88 2.44 - 3.32 < 0.001
Excellent 386 (37.9)
Fair 570 (56.0)
Poor 62 (6.1)
Sport Activity 0.64 0.25 - 1.03 < 0.05
Daily 474 (46.6)
Sometimes 459 (45.1)
Rarely 85 (8.3)
Breakfast Intake 0.88 0.45 - 1.32 < 0.05
Daily 774 (76.0)
Sometimes 179 (17.6)
Rarely 65 (6.4)
BMI 20.1 [19.9 - 20.3]† 0.04 –0.11 - 0.19 0.58
Waist Circumference(cm) 68.5 [67.8 - 69.1]† 0.03 –0.03 - 0.08 0.36
*Numbers in parentheses indicate the percentages; †Mean and 95% CI in parentheses are shown.
fulfill the criteria of CFS is an important issue in fatigue
research. Previous reports from western countries dealt
with this theme mainly by using self-reported question-
naires such as Chalder’s scales [14] or the Checklist In-
dividual Strength (CIS) [15]. Considering quite subjec-
tive nature of fatigue, a self-reported questionnaire is
thought to be the reliable and useful method of collect-
ing activity data from a large population of adolescents
[16]. Although there were differences in the definition of
persistent fatigue among previous studies from western
countries, the following consistencies were found [8-10,
12,13]: 1) persistent fatigue was more common in fe-
N. Zou et al. / Health 3 (2011) 271-275
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
males than in males, 2) the prevalence of persistent fa-
tigue increased with age, 3) persistent fatigue was ac-
companied by psychological disorders such as depres-
sion and anxiety, and 4) the appearance of persistent
fatigue was associated with lifestyle. Among lifestyle,
unhealthy dietary life and irregular sleep habits have
been demonstrated as causative factors of persistent fa-
In comparison with western countries, the epidemiol-
ogical study of fatigue in healthy adolescents in Asian
countries is quite scanty. Okamoto et al. investigated the
characteristics of fatigue in association with lifestyle in
247 healthy Japanese adolescents and found that the
complaints most frequently observed were drowsiness
and dullness, followed by difficulty of concentration
[17]. Moreover, undesirable eating habits or poor life-
style, such as staying up late at night, were associated
with the degree of fatigue. Recently, it is reported that
fatigue is largely affected by physical fitness level but
very little by exercise habits in healthy Japanese adoles-
cents aged 15 - 20 years [18]. We have recently reported
the fatigue status in 1225 Japanese adolescents aged
between 11 and 16 yrs by the questionnaire used in the
present study, but the method of data collection was
“self-reported” [19]. In this study, the fatigue scores in-
creased significantly with age, but there was no gender
difference at any age. Moreover, subjects with higher
fatigue scores tended to skip breakfast more frequently,
and to have less balanced eating habits or lesser sleep
duration, as in the present study. “To feel sleepy in the
daytime” was the commonest complaint followed by “to
feel often tired”. On the other hand, “lack of concentra-
tion” was the 5th most common complaint. We are un-
certain about the reason for this disparity in findings
between Chinese and Japanese adolescents. One possible
explanation is that there exist basic differences of daily
lifestyle in adolescents between Jixi and Nara cities,
although both cities are classified as middle class urban
cities in their respective countries.
There are several limitations in the present study. First,
we developed our own simple questionnaire for investi-
gating the fatigue status. The advantage of using such a
simple questionnaire for both participants and physicians
is to shorten the time required for answering. However,
this questionnaire makes it difficult to compare our re-
sults with those of previous studies. Second, the precise
details of the identified lifestyle were not fully clarified.
For example, the evaluation of diet life was only about
the frequency of skipping breakfast. It would be useful
to collect detailed information about nutrient intake
through diet. Finally, we did not investigate the rate of
school absence. School absence is thought to be appar-
ently a serious outcome of persistent fatigue [11]. De-
spite these limitations, we believe that our findings have
potential implications, since this is the first study, as far
as we know, to examine the fatigue status in healthy
Chinese adolescents. Chinese adolescents are exposed to
high stress due to the competitive and punitive educa-
tional environment in China [20]. Therefore, further col-
lection of fatigue data in other districts such as metro-
politan or rural cities is warranted for understanding
overall fatigue status in the community of Chinese ado-
lescents. Based on such investigation, a plan of inter-
vening lifestyle in adolescents to minimize fatigue
should be considered as a future project.
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Please score elements from 0 to 3 in boxes as the av-
erage for the past one month. (0: not at all, 1: a few times
per month, 2: a few times per week, 3: almost every day)
A. Physical fatigue-related elements
1. ( ) How often do you feel tired?
2. ( ) How often do you feel tired after sleeping at
3. ( ) How often do you feel like lying down in the
4. ( ) How often do you feel forceless?
B. Mental fatigue-related elements
1. ( ) How often do you feel anxious about your
2. ( ) How often do you feel a lack of concentration
to do something?
3. ( ) How often do you feel sleepy in the daytime?
4. ( ) How often do you feel depressed without any
special reasons?