BIOMEDICAL AND ENVIRONMENTAL SCIENCES 20, 19-23 (2007)
Report on Childhood Obesity in China (6)
Evaluation of a Classroom-based Physical Activity Promotion Program1
AI-LING LIU, XIAO-QI HU, GUAN-SHENG MA2, ZHAO-HUI CUI, YONG-PING PAN*,
SU-YING CHANG#, WEN-HUA ZHAO#, AND CHUN-MING CHEN#
National Institute for Nutrition and Food Safety, Chinese Center for Disease Control and Prevention, 29 Nanwei Road,
Beijing 100050, China; *Dongcheng School Healthcare Institute, Beijing 100007, China; #International Life Science
Institute Focal Point-China, Beijing 100050, China
Objectives To evaluate the effect of Happy 10 program on the promotion of physical activity, physical growth and
development of primary-school students, and on obesity control and prevention. Methods Two similar primary schools
from one district of Beijing, China were selected, one as an intervention school and the other as a control school. Happy 10
program was implemented at least once every school day in the intervention school for two semesters, whereas no intervention
was adopted in the control school. The information on energy expenditure and duration of physical activity was collected by a
validated 7-day physical activity questionnaire. Height and weight were measured by trained investigators following the
standardized procedure. Energy expenditure and intensity of each Happy 10 session was measured by a physical activity
monitor. Results The average energy expenditure and duration of total physical activity per day among students in the
intervention school increased significantly from 15.0 to 18.2 kcal/kg, and 2.8 to 3.3 h respectively, whereas the figures
significantly decreased in the control school. There was a significant difference in change of weight and BMI between girls in
the intervention and control school (2.4 kg vs 4.6 kg, -0.47 kg/m2 vs 0.66 kg/m2). The prevalence of overweight and obesity in
the intervention school decreased by 0.4%-5.6%, as compared to the increase by 0.6%-4.5% in the control school. The average
energy expenditure and intensity per 10-minute session ranged from 25.0-35.1 kcal, 4.8-6.2 kcal/kg/h respectively in grades 1-5.
Conclusion Happy 10 program provides a useful strategy to promote physical activity among school children and also plays a
positive role in building up physical growth and development of girls.
Key words: Happy 10; Physical activity; Obesity; Intervention
Regular participation in physical activity is an
essential component of healthy lifestyle, which helps
to prevent certain chronic childhood conditions,
including hypertension, diabetes, obesity, abnormal
lipid profiles, as well as depression. However,
physical inactivity among children and adolescents is
becoming a major concern in China. Children and
adolescents spend more time on sedentary activities,
such as viewing TV, using internet and playing
computer games, instead of doing physical activities.
It is indicated that only 9.2% of children aged 6-12
years are doing exercise more than three times/week
with duration of more than 20 minutes, while
41.4% of them spend at least two hours on watching
To respond to the need for increasing physical
1This research was funded by International Life Science Institute Focal Point-China.
2Correspondence should be addressed to Guan-Sheng MA. Tel: 86-10-83132572. Fax: 86-10-83132021. E-mail: email@example.com
Biographical note of the first author: Ai-Ling LIU, female, born in 1972, professor, majoring in nutrition, physical activity of children
and adolescents and chronic disease control and prevention.
activity level among school-aged children, a
program—Happy 10 was initiated by the National
Institute for Nutrition and Food Safety, Chinese
Center for Disease Control and Prevention, based on
the principle of TAKE 10!TM. The Happy 10
program was implemented in urban Beijing since
2004. The purpose of the present study is to evaluate
the effect of the program on the promotion of
physical activity, physical growth and development
of school children, and on obesity control and
prevention among them.
SUBJECTS AND METHODS
Two similar primary schools were selected from
the same district of urban Beijing, one school (14
classes) as an intervention group and the other (12
Copyright © 2007 by China CDC
20 LIU ET AL.
classes) as a control group.
Happy 10 program is a classroom-based physical
activity program for primary-school students which is
based on the principle of “TAKE 10!TM” Program
developed by the Health Promotion Center of
International Life Science Institute in USA. Many
safe and age- and space-appropriate physical
activities are included in the program materials.
Happy 10 program was actually organized and
implemented by the teachers among students in
grades 1-5 in the intervention school, taking about 10
minutes at least once every school day. Tracking
posters and stickers were used to illustrate progress of
each grade. The program covered in total two
semesters from October 2004 to June 2005. No
intervention was implemented in the control school.
Information on age, gender, height, weight and
physical activity patterns of all students in both
intervention and control schools were collected pre-
and post-intervention. The height and weight were
measured by the trained investigators following the
standardized procedure. Information on physical
activity patterns was collected using a validated
7-day physical activity questionnaire which was
interviewed administrated for students of grade 1-2
and self-administrated for students of grade 3-5. The
average energy expenditure and duration of total
physical activity per day were calculated from the
questionnaire. Body mass index (BMI) was
calculated as weight (kg) divided by square of height
(m). The overweight and obesity was defined by age-
and sex-specific BMI, which is recommended by
Group of China Obesity Task Force.
The energy expenditure of each session of Happy
10 was measured using a physical activity monitor
(Zhi-Ji UX-01, Beijing YHKI Sci-Tech Development
Co. LTD) worn on left side of the front waist. A
total of 80 students (8 boys and 8 girls from each
grade) were selected in the intervention school. Each
student was evaluated for five consecutive
schooldays. The monitors were worn just before each
session of Happy 10 and removed after the session was
over, and the teachers recorded the type and duration
of activities implemented and figures displayed
by the monitors at the end of each session. The
energy expenditure per session was read directly
from the monitors and the metabolic rate (MET)
was calculated as energy expenditure divided by
weight, which was used to assess the intensity of the
The mean and standard deviation were used to
describe continual variables. An analysis of variance
(ANOVA) and Chi-square test were used to compare
the difference in daily energy expenditure and
duration of physical activity, height, weight, BMI and
prevalence of overweight and obesity among various
groups. All P-values were two-sided. A level P<0.05
was accepted as statistical significance.
A total of 753 students (357 boys, 396 girls) aged
6-12 years were investigated. Three hundred and
twenty eight students (150 boys and 178 girls) were
from the intervention school, while 425 students (207
boys and 218 girls) were from the control school.
Comparison of Change of Daily Physical Activity
Level Between the Intervention and Control School
Table 1 shows the change of daily energy
expenditure and duration of physical activity before
and after the intervention. Significant increases in the
average daily physical activity energy expenditure
(PAEE) and duration among the students in the
intervention school were found before and after the
intervention (15.0 kcal/kg vs 18.2 kcal/kg, 2.8 h vs
3.3 h respectively). In the contrast, significant
decreases of these two variables were found in the
control school (24.3 kcal/kg vs 14.7 kcal/kg, 4.4 h vs
2.9 h respectively). There was significant difference
in change of energy expenditure and duration of
physical activity between the intervention school and
the control school.
Change of Energy Expenditure and Duration of Physical Activity of Students Pre- and Post-intervention1
Intervention School (n=328)
PAEE (kcal/kg/d) 15.0 18.2
Moderate 5.0 6.7
Vigorous 8.8 10.3
PA Time (h/d) 2.8 3.3
Vigorous 1.1 1.4
Note. PAEE: Physical activity energy expenditure; PA: Physical activity; 1analysis of variance (ANOVA); * there was significant
difference pre- and post-intervention within the group; # there was significant difference of change between the intervention school and the
control school after the intervention.
Control School (n=425)
EVALUATION OF CLASSROOM-BASED PHYSICAL ACTIVITY
Comparison of Change of Height, Weight, and BMI
Between the Intervention and Control School
It can be seen from Table 2 that there was a
significant increase of height and weight after eight
month intervention in both the intervention and
control schools. But there was no significant
difference in the change of height and weight
between the intervention and control school except
the change of weight between the intervention girls
and the control girls (2.4 kg vs 4.6 kg). The BMI of
boys in both the intervention and control schools and
girls in the control school increased significantly after
the intervention. But the figure of girls in the
intervention school decreased significantly from
18.63 kg/m2 to 18.16 kg/m2, and there was a
significant difference in the change of BMI between
the intervention girls and the control girls.
Change of Height, Weight, and BMI of Students Pre- and Post-intervention1
Intervention School (n=328)
Note. 1Analysis of variance (ANOVA). *There was significant difference pre- and post-intervention within the group; #there was
significant difference in change between the intervention school and the control school after the intervention.
Comparison of Change of Prevalence of Overweight and
Obesity Between the Intervention and Control School
Control School (n=425)
The prevalence of overweight and obesity in the
intervention school was 20.9% and 15.0% for boys,
and 15.3% and 16.9% for girls before the intervention,
which decreased to 17.1% and 14.6%, 12.0% and
11.3% respectively after two-semester intervention.
On the contrast, the prevalence of overweight and
obesity in the control school increased by 0.6%-4.5%
during the same period of time. There was no
significant difference in change of the prevalence of
overweight and obesity between the intervention
school and the control school (Table 3).
Change in the Prevalence of Overweight and Obesity Among Students Pre- and Post-intervention (%)1
Intervention School (n=328)
Control School (n=425)
Note. 1Chi-square test.
Average Energy Expenditure and Intensity for One
Session of Happy 10
Table 4 indicates the energy expenditure level
and intensity of children for each session of Happy
10. The average caloric expenditure per session of
each grade ranged from 25.0 to 35.1 kcal. There was
a significant difference in energy expenditure among
grades, and it was highest among the students in
grade 3. After adjustment for body weight, the
average METs value per session of each grade ranged
from 4.8 to 6.2 kcal/kg/h. All sessions were
associated with MET value in the moderate (3≤
METs<6) to vigorous (METs≥6). Students in
grade 3 were most active among students in the
intervention school. They had 4 days with vigorous
activities (METs 7.3 kcal/kg/h). The METs of
students in grade 5 during the five-day session ranked
22 LIU ET AL.
Energy Expenditure and Intensity per Happy 10 Session by Grade
Energy Expenditure (kcal) Intensity (kcal/kg/h)
Classroom-based physical activity program
provides a unique opportunity to enhance the current
health status of children during their critical periods
of growth and development because virtually all
children attend school. In addition, physical activity
is a lifetime course tracking from one’s childhood to
adulthood. That is why researchers and medical
practitioners recommend that school based physical
activity interventions be developed. Happy 10 is a
classroom-based physical activity intervention for
Chinese primary-school students. This study is
designed to evaluate effectiveness of the Happy 10
intervention in promoting physical activity level
among children and to examine its influence on
physical growth and development, as well as on
obesity control. The findings of the present study
have confirmed that Happy 10 is a useful
classroom-based physical activity intervention.
Our findings have indicated that Happy 10 is
effective in increasing physical activity level among
students in grades 1-5. Participants in individual
Happy 10 session burned a modest number of kcal,
ranging from 25.0 to 35.1 per 10-minute session,
which was similar to the TAKE 10! activities.
Participants achieved exercise intensities in the
moderate to vigorous range at the activity session.
Exercise intensity varied by grade levels because of
the different activities involved and different rhythms
and extents of the same activity. Students in lower
grades were more active than those in higher grades.
Energy expenditure and intensity per session did not
mean single Happy 10 activity’s energy expenditure
and intensity. Two to three activities were actually
involved in one session because students liked this
pattern, which was more attractive than doing only
one activity at each session. Although a relatively
small number of energy was expended per session,
the most important thing was that students were
encouraged to participate in more physical activities
using the skills and knowledge learned from Happy
10 on other occasions. Total daily energy expenditure
increased by 3.1 kcal/kg/d after the intervention
among students in the intervention group, while it
decreased among their
expenditure accumulated in such a way may create a
positive impact on maintaining healthy body weight
and preventing the development of overweight and
There is significant difference in change of
weight and BMI after the intervention only between
the intervention girls and the control girls. Such
results can be explained by the following factors.
First, more attention is paid on body shape by girls
and girls’ body dissatisfaction scores is significantly
higher than boys’, therefore they may keep more
active during Happy 10 than boys. Second, the
physical activity level of boys is higher than that of
girls, so the Happy 10 program exerts relatively
less influence on the physical activity level of the
former. The program’s
development may be insignificant.
Although overweight and obesity data showed
no significant differences between the intervention
and control school, there was a positive change taken
place pre- and post-intervention. The prevalence of
overweight and obesity among the intervention
students decreased, while the figure among the
control students increased at the same period. No
significant difference was likely due to the influence
of other factors, such as short time, dietary practice
and small sample size.
Findings of the present study suggest that Happy
10 can increase the physical activity level of children
and can positively influence their health status.
Moreover, it is well accepted by the participants.
Teachers involved in implementing Happy 10
indicate that the program is easy to implement and
activities are enjoyable and attractive to their students.
They will be interested to implement this program in
the next semester. Students are active to participate in
all sessions. Parents also support their children to
take part in the program. In conclusion, it is feasible
to implement Happy 10 program in China.
effect on physical
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(Received November 8, 2006 Accepted December 19, 2006)