A study of fatigue status in Chinese adolescents in an urban city, Jixi

doi:10.4236/health.2011.35048

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Vol.3, No.5, 271-275 (2011)

doi:10.4236/health.2011.35048

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.

ABSTRACT

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

1. INTRODUCTION

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. MATERIALS AND METHODS

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

272

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. RESULTS

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.

4. DISCUSSION

In healthy adolescents, persistent fatigue that does not

Table 1. Factor analysis of the fatigue questionnaire used in the

present study.

Factors

Items

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

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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

274

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-

tigue.

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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APPENDIX

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

night?

3. ( ) How often do you feel like lying down in the

daytime?

4. ( ) How often do you feel forceless?

B. Mental fatigue-related elements

1. ( ) How often do you feel anxious about your

health?

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?