Hành vi ít vận động có liên quan với tăng nguy cơ bệnh mãn tính và hành vi ít vận động đang gia tăng trong thanh thiếu niên. Dữ liệu về những thay đổi trong hành vi định canh định cư ở các nước đang phát triển bị hạn chế. Mục đích Để mô tả 5 năm thay đổi theo chiều dọc trong giờ ít vận động nonschool trong thanh thiếu niên đô thị tại thành phố Hồ Chí Minh, và để xác định mối tương quan với sự thay đổi này. Phương pháp Đây là 5 năm nhóm theo chiều dọc với lấy mẫu ngẫu nhiên hệ thống của 759 sinh viên đến từ 18 trường trung học cơ sở. Tất cả các biện pháp đã được thực hiện hàng năm từ năm 2004 đến năm 2009. Hành vi Định canh định cư được đánh giá bằng tự báo cáo và accelerometry. Mô hình tiềm ẩn và hỗn hợp tuyến tính tổng quát được sử dụng để phân tích dữ liệu trong năm 2011. Kết quả Từ năm 2004 đến năm 2009, thời gian tự báo cáo chi tiêu trong hành vi ít vận động nonschool tăng 498603 phút ngày. Trong năm khảo sát lần thứ 5, nam và nữ (từ 16 tuổi) tương ứng là 3,6 lần (95% CI = 2.3, 6.0) và 3,1 lần (95% CI = 1,8, 5,0) nhiều khả năng dành ≥ 2 giờ ngày vào thời gian màn hình so với ban đầu (từ 12 tuổi). Dữ liệu tốc điều chỉnh cho thời gian mặc tiết lộ rằng nam và nữ từ 16 tuổi có, tương ứng, ở phút thứ 78 ngày (95% CI = 48, 104) và 69 phút ngày (95% = 34, 95) nonschool nhiều thời gian ít vận động hơn những người có đánh giá tốc đầu tiên (ở tuổi 13 năm). Cô gái trong tứ phân vị kinh tế xã hội cao nhất dành một 90 phút bổ sung ngày trong hành vi ít vận động so với các cô gái trong tứ phân vị thấp nhất (95% CI = 52, 128). Kết luận Hành vi ít vận động Nonschool tăng trong thanh thiếu niên Việt Nam có độ tuổi. Sự gia tăng lớn nhất là trong thời gian màn hình giải trí (28%), đó sẽ là mục tiêu rõ ràng nhất cho các chiến lược y tế dự phòng.
Trang 1Longitudinal Sedentary Behavior Changes in
Adolescents in Ho Chi Minh City
Nguyen H.H.D Trang, MD, MSc, Tang K Hong, MD, PhD, Hidde P van der Ploeg, PhD, Louise L Hardy, PhD, Patrick J Kelly, PhD, Michael J Dibley, MBBS, MPH
This activity is available for CME credit See page A4 for information.
Background:Sedentary behavior is associated with increased risk of chronic disease and sedentary
behavior is increasing among adolescents Data on changes in sedentary behavior in developing
countries are limited
Purpose:To describe 5-year longitudinal changes in nonschool sedentary hours among urban
adolescents in Ho Chi Minh City, and to identify correlates with this change
Methods:This is a 5-year longitudinal cohort with systematic random sampling of 759 students
from 18 junior high schools All measures were taken annually between 2004 and 2009 Sedentary
behavior was assessed by self-report and accelerometry Generalized linear latent and mixed models
were used to analyze the data in 2011
Results:Between 2004 and 2009, self-reported time spent in nonschool sedentary behavior
increased from 498 to 603 minutes/day In the 5th survey year, boys and girls (aged 16 years)
were, respectively, 3.6 times (95% CI⫽2.3, 6.0) and 3.1 times (95% CI⫽ 1.8, 5.0) more likely to
spendⱖ2 hours/day on screen time compared with baseline (aged 12 years) Accelerometer data
adjusted for wearing time revealed that boys and girls aged 16 years had, respectively,
78 minutes/day (95% CI⫽48, 104) and 69 minutes/day (95% CI⫽34, 95) more nonschool
sedentary time than those at the fırst accelerometer assessment (at age 13 years) Girls in the
highest socioeconomic quartile spent an additional 90 minutes/day in sedentary behavior
compared with girls in the lowest quartile (95% CI⫽52, 128)
Conclusions:Nonschool sedentary behavior increased among Vietnamese adolescents with age
The largest increase was in recreational screen time (28%), which would be the most obvious target
for preventive health strategies
(Am J Prev Med 2013;44(3):223–230) © 2013 American Journal of Preventive Medicine
Introduction
Sedentary behaviors increase the risk of obesity1–3
and the development of a range of chronic
dis-eases.4 – 6In children and adolescents, leisure-time
sedentary behaviors, such as TV viewing, have been
associated with metabolic risk factors, independent of
physical activity levels.4,7In recent decades, the
oppor-tunities to be sedentary have increased, and young
people tend to be more sedentary than those in previ-ous generations.8,9
Although much is known about correlates of physical activity,10little is known about correlates of sedentary be-haviors among adolescents, despite the belief that the deter-minants of sedentary behavior are distinct from those of physical activity.11,12 In addition, sedentary behavior ap-pears to carry over more than physical activity from child-hood to adolescence,13and may even have a greater influ-ence on the development of overweight and obesity than physical activity.14,15
Data on sedentary behaviors are available for devel-oped countries,16 –20but they are lacking for develop-ing nations.21 Moreover, current studies are mostly cross-sectional and focused on only screen time (i.e.,
TV, videos/DVDs, recreational computer use), which has been used widely as a proxy measure of sedentary behavior among youth.7,22,23Few studies have
exam-From the Department of Community Health (Trang, Hong), Pham Ngoc
Thach University of Medicine, Ho Chi Minh City, Vietnam; Sydney School
of Public Health (Trang, Kelly, Dibley), and Prevention Research
Collabo-ration (van der Ploeg, Hardy), The University of Sydney, New South Wales,
Australia; and the Department of Public and Occupational Health (van der
Ploeg), VU University Medical Center Amsterdam, the Netherlands
Address correspondence to: Nguyen H.H.D Trang, MD, MSc, Pham
Ngoc Thach University of Medicine, 86/2 Thanh Thai Street, District 10,
Ho Chi Minh City, Vietnam E-mail: nguyenhoang_doantrang@yahoo.
com
0749-3797/$36.00
http://dx.doi.org/10.1016/j.amepre.2012.10.021
Trang 2ined a broad range of sedentary behaviors
longitudi-nally among adolescents.24
Identifıcation of the correlates of a full range of
seden-tary behaviors in adolescents is needed to develop
more-effıcient preventive action to decrease sedentary behavior
and risk of chronic disease including excess adiposity in
developing countries, such as Vietnam The purpose of
the current study was to describe the longitudinal
changes in sedentary behavior among adolescents in
ur-ban Vietnam who participated in the Ho Chi Minh City
Youth Cohort study between 2004 and 2009, and to
iden-tify individual, family, and environmental factors
associ-ated with screen time and sedentary behavior over this
5-year period
Methods
Study Design
The Ho Chi Minh City (Vietnam) Youth Cohort study was a 5-year
longitudinal study that began in 2004 from a multistage cluster
cross-sectional survey The study examined the weight status and
weight-related behaviors among adolescents in this city The
sur-vey covered 140 junior high schools from which 31 clusters
(schools) were selected.
Systematic random sampling was used to select 18 junior high
schools, of which 11 were from wealthy districts and seven were
from less-wealthy districts for the cohort 25 In each school, one
class was taken from two classes (one from Grade 6 and one
from Grade 7) combined The two classes were selected by
simple random sampling in the cross-sectional study All
stu-dents in the selected classes were invited to participate in the
study (N ⫽784), and 759 students consented to participate in the
cohort.
Data were collected by trained fıeld staff on fıve occasions, 1 year
apart, on adolescents who consented to take part in the study.
Consent, from both the adolescents and their parents, was required
for participation in the cohort study The study was approved by
the Research Ethics Committee, Pham Ngoc Thach University of
Medicine, Ho Chi Minh City, and the Human Research Ethics
Committee of the University of Newcastle, Australia.
Data Collection
Information on sedentary behaviors was measured using the
Ado-lescent Sedentary Activity Questionnaire (ASAQ), 26 validated in
Vietnamese adolescents, 27 which asked students to report the time
spent outside of school hours for each day of the week in a range of
sedentary activities Daily time spent in sedentary behavior was
com-puted as the total of all recorded sedentary activities, categorized by
sedentary domains: screen time (watching TV/video, playing
puter games, using computer for fun); educational time (using
com-puter for study, studying at home, studying in afterschool class); other
leisure time (reading books, chatting with friends, talking on phone,
doing hobbies, music or painting lesson/practice); and passive
com-muting to school (i.e., by car, bus, motorbike).
One year after baseline (Year 2005), students’ sedentary
behav-ior also was assessed objectively for 7 days with an Actigraph
accelerometer (model GT1M) worn on the right hip 28 Sedentary
time was defıned as ⬍100 counts per minute 29,30 Nonwear time
was defıned as 10 minutes of consecutive zeroes 31 Only partici-pants who wore the accelerometer for ⱖ8 hours per day on at least
4 days were included in the analysis Physical activity was assessed using the Vietnamese Adolescent Physical Activity Recall Ques-tionnaire (V-APARQ) 32 The Spearman and intraclass correla-tion coeffıcients showed this quescorrela-tionnaire to be valid and reli-able, with a weighted kappa of 0.75, indicating that the V-APARQ is useful for monitoring change in physical activity among Vietnamese adolescents.
Anthropometric measurements were taken by trained fıeld staff Participant weight (in kilograms; without shoes or heavy clothing) was measured using a Tanita BF 571 electronic scale and recorded
to the nearest 100 g Standing height (in centimeters) was measured with a suspended Microtoise tape to the nearest 0.1 cm BMI was calculated, and overweight and obesity were defıned using the International Obesity Task Force cutpoint values 33 In a confıden-tial setting, the adolescents self-reported their pubertal status using Tanners’ fıve stages of pubertal development for pubic hair, and male genitalia or female breasts; for female students, the date of menarche also was recorded 34
The student’s parents also completed a questionnaire provid-ing information on household SES, and their personal charac-teristics SES was assessed through questions on ownership of 14 assets that were used to construct a household wealth index Responses were ranked and divided into quartiles of SES Par-ents also reported on the availability of computer game stores, home rules on playing computer games, presence of a TV in the child’s room, and frequency of the parents’ doing exercises with their child.
Data Analysis
Analyses were conducted using Stata, version 11 Models were fıtted using the generalized linear latent and mixed models (GLLAMM) package in Stata 35 Multilevel models were used to take account of the clustering of observations within schools and for repeated student observations Data were weighted according to school size Screen time was categorized according to recom-mended guidelines ( ⬍2 and ⱖ2 hours/day) 36 To determine fac-tors that could predict the change in the prevalence of ⱖ2 hours/ day screen time, multilevel multivariable logistic regression models were used, and multilevel multivariable linear models were used for continuous data.
Results were stratifıed by gender because participation in seden-tary behaviors differed between boys and girls, 37 and an interaction
was found between gender and sedentary time (p⫽0.004)
Vari-ables with a univariate p-value⬍0.25 were entered into the multi-variable model 38 Stepwise backward elimination was used, and
variables were removed from the model if their adjusted p-value
was ⬎0.05 Only signifıcant factors were presented.
Results
At baseline, 759 adolescents consented to participate in the study, and complete data from the 5 survey years were available for 585 (77%) adolescents At baseline, the mean age of the students was 11.8 years (⫾0.6) The baseline characteristics of the students (Table 1) showed that 14.2% of students were overweight or obese The majority
of students did not have a TV in their bedroom (92%);
Trang 3had a computer game store nearby (95%); and had
paren-tal rules limiting screen time (95%)
Self-reported time spent in various domains of
seden-tary behaviors by survey year is shown inTable 2 Over
the 5-year period, sedentary behavior increased by
21% (p⬍0.001; from an average of 498 minutes/day to
603 minutes/day) At each survey year, the most common sedentary domain was afterschool educational activities,
Table 1 Baseline characteristics of adolescents, M (SD) or % (95% CI)
Boys
(n⫽364)
Girls
(n⫽395)
Total (N ⫽759)
BMI status a
Not overweight/obese 78.2 (73.7, 82.7) 86.5 (82.9, 90.0) 82.5 (79.7, 85.4)
Overweight/obese 21.8 (17.3, 26.3) 13.5 (9.9, 17.1) 17.4 (14.6, 20.3)
Pubertal status
Pubescent and postpubescent 54.1 (48.8, 59.4) 77.9 (73.7, 82.0) 66.6 (63.2, 70.1)
Did not complete junior high
school
24.6 (19.9, 29.3) 26.7 (22.2, 31.2) 25.7 (22.5, 29.0)
Did not complete high school 21.6 (17.1, 26.0) 22.3 (18.1, 26.6) 22.0 (18.9, 25.1)
Completed high school or higher 53.8 (48.4, 59.2) 50.9 (45.8, 56.1) 52.3 (48.6, 56.0)
Did not complete junior high
school
19.1 (14.9, 23.4) 22.6 (18.3, 26.9) 21.0 (17.9, 24.0)
Did not complete high school 20.1 (15.7, 24.4) 21.0 (16.8, 25.2) 20.5 (17.5, 23.6)
Completed high school or higher 60.8 (55.5, 66.1) 56.4 (51.3, 61.5) 58.5 (54.8, 62.1)
Both not overweight/obese 71.1 (65.9, 76.4) 72.1 (67.2, 77.0) 71.6 (68.1, 75.2)
Father overweight/obese 7.6 (4.5, 10.6) 7.1 (4.3, 9.8) 7.3 (5.2, 9.4)
Mother overweight/obese 17.9 (13.4, 22.3) 16.6 (12.5, 20.6) 17.2 (14.2, 20.2)
a Defined by using International Obesity Task Force cutpoint
b Based on household wealth index
Trang 4accounting for 38%– 40% of total sedentary time,
followed by screen time (30%–34%) and other leisure
activities (17%–20%) Over the 5-year period, screen time
increased by 28% (p⬍0.001); afterschool educational
ac-tivities increased by 27% (p⬍0.001); and other sedentary
leisure-time activities increased by 14% (p⬍0.01) At
baseline, 81.5% students have more than 2 hours of screen
time/day, increasing to 86.4% in 5 years (p⫽0.01).
Figure 1shows the median time (minutes/day) spent in
three main domains of sedentary behavior outside of
school hours by gender and survey year For both boys
and girls, time spent in afterschool educational activities
and screen time increased at each survey year Boys
con-sistently engaged in more screen time than girls across
survey years (p⬍0.001) At baseline, screen time was
160 minutes/day and 144 minutes/day and increased over
the 5-year period to 215 minutes/day and 190 minutes/
day, for boys and girls respectively In contrast, girls spent
signifıcantly more time in afterschool educational
activi-ties than boys, especially in the third survey year when
students transitioned into high school, although
educa-tional time did increase in both boys and girls
The correlates of screen time ofⱖ2 hours/day by gen-der show that in the 5th survey year, boys (mean age
16 years) were 3.6 times (OR⫽3.6, 95% CI⫽2.3, 6.0) as likely to spendⱖ2 hours/day on screen time compared with baseline screen time (mean age 12 years) Similarly,
in the 5th survey year, girls (mean age 16 years) were three times (OR⫽3.1, 95% CI⫽1.8, 5.0) as likely to spend ⱖ2 hours/day on screen time compared with baseline screen time (mean age 12 years) Girls from the highest SES quartile were also twice as likely to spendⱖ2 hours/ day on screen time than their counterparts from the low-est SES quartile (OR⫽2.1, 95% CI⫽1.3, 3.4)
The correlates of time in total sedentary behavior (Table 3) show that in the 5th survey year (mean age
16 years), boys had increased their daily sedentary time
by 121 minutes/day (95% CI⫽98, 160) compared with baseline, whereas sedentary behavior among girls in-creased 115 minutes/day (95% CI⫽96, 163) over the 5-year period Girls in the highest SES quartile had an additional 90 minutes of daily sedentary time compared with peers in the lowest SES quartile (95% CI⫽52, 128)
Table 2 Sedentary behavior time (minutes/day) outside of school hours, by categories and survey year
2004/2005
n⫽759 2005/2006n⫽740 2006/2007n⫽712 2007/2008n⫽630 2008/2009n⫽585
Self-reported time (ASAQ; minutes) 498 (180) 558 (201) 601 (210) 604 (215) 603 (212) Screen time 158 (102, 243) 165 (114, 283) 172 (163, 287) 205 (156, 275) 203 (157, 264)
Using computer for fun/games 31 (17, 60) 40 (27, 69) 50 (34, 114) 63 (44, 89) 72 (46, 120) ⱖ2 hours screen time/day,
% (95% CI)
81.5 (78.9, 84.2) 82.8 (80.0, 85.1) 83.2 (80.6, 85.8) 85.7 (83.2, 88.4) 86.4 (83.5, 89.2)
Total afterschool educational time 191 (148, 236) 196 (150, 244) 244 (192, 309) 240 (184, 321) 242 (197, 326) Computer use for education 21 (14, 34) 26 (16, 39) 27 (21, 43) 30 (19, 51) 35 (18, 56) Noncomputerized study 101 (60, 146) 110 (70, 139) 125 (94, 174) 118 (69, 154) 120 (80, 164)
Total other leisure-time sedentary
behavior
108 (65, 143) 116 (75, 211) 103 (85, 148) 120 (114, 175) 123 (112, 160)
Sitting chatting with friends/talking
on phone
26 (14, 49) 40 (10, 76) 36 (11, 72) 50 (30, 83) 45 (29, 77)
Hobbies/music/recreational
practices
56 (34, 90) 51 (29, 84) 45 (28, 88) 50 (29, 95) 52 (43, 105)
Note: Values are M (SD) or median (25th percentile, 75th percentile), unless otherwise noted; —⫽ no observation.
ASAQ, Adolescent Sedentary Activity Questionnaire
Trang 5Accelerometer data, adjusted for wearing time, showed
that sedentary behavior increased by 78 minutes/day
(95% CI⫽48, 104) among boys and 69 minutes/day
(95% CI⫽34, 95) among girls between the 2nd and 5th
survey year Physical activity and environmental factors
were not associated with the changes in screen time and
sedentary behavior Changes in BMI were not associated
with changes in sedentary behavior (data not shown)
Discussion
This is the fırst study to present longitudinal changes
across a broad range of sedentary behaviors and to
pro-vide a better understanding of relevant correlates of
screen time and sedentary behavior among Vietnamese
adolescents The study fındings are important to the
de-sign of interventions dede-signed to decrease the sedentary
lifestyles that are becoming increasingly common in
de-veloping countries such as Vietnam This study showed
an increase in nonschool sedentary time in a
representa-tive sample of adolescents aged 12–16 years in urban Ho
Chi Minh City Afterschool educational sedentary time
and screen time accounted for more than two thirds to
three quarters of total sedentary time, respectively,
out-side school hours Age, gender, and SES were related to
screen time and total sedentary time
The increase in screen time with age found in the
present study is similar to increases reported by
longi-tudinal studies in developed countries.13,39,40 This
fınding may be due to the substantial amount of
free-dom adolescents have in Vietnam to engage in screen
time and the increased access and availability of screen
technologies Ownership of a TV among those in ur-ban areas in Vietnam has increased from 77% in 1999
to 91.3% in 2009.41
Likewise, Internet usage has increased signifıcantly from 12.8% to 25.7% from 2005 to 2009.42 Among all screen behaviors, TV time only increased slightly, a fınd-ing in accordance with previous studies that reported the stability of TV time.43The median screen time of Viet-namese adolescents was above the recommended level of
⬍2 hours/day in all 5 survey years (2.5–3.5 hours per day) This is higher than the level found in a study in urban Chinese adolescents in 2004 –2006 that reported 1.2–1.7 hours/day of screen time,44and it is more closely aligned with fındings of adolescents’ screen time in the U.S and Canada, where daily screen time exceeds
4 hours/day.45
The present fınding that Vietnamese youth report a large amount of time in afterschool educational sedentary behaviors is similar to results reported among Chinese adolescents.44This result may be due to the high priority placed on education in Asian cultures, where academic pressure is put on the students by their parents and schools The time spent in sedentary educational activi-ties increased steeply after 3 years of follow-up in both boys and girls, corresponding to the time when students are preparing for junior high school graduation exams, followed by entry into high school During this time, students often spend more time on extracurricular tutor-ing in addition to homework, includtutor-ing eventutor-ing classes in private institutions and private classes preparing students for the fınal junior high school examination
In the present study, time spent hanging out chatting with friends increased substantially and is also an impor-tant sedentary leisure-time activity for Vietnamese ado-lescents During adolescence, teenagers begin to spend increasingly more time away from their parents and are more exposed to schools, peers, and other socialization agents Time spent hanging out and socializing therefore increased correspondingly.46
Consistent with other studies,37,44,47,48 boys reported higher screen time than girls This may be because girls take part in more activities other than screen time, such as housework and extracurricular cultural activities In Vietnamese culture, girls are expected to help their moth-ers with household activities, especially cooking, prepar-ing the table for dinner, and cleanprepar-ing; boys may follow their fathers’ behavioral patterns, which allow for more screen time
In the present study, older children were more likely to have 2 or more hours of daily screen time as well as total sedentary time These fındings are in agreement with other studies that focused on screen time.13,49,50 The present study showed that screen time was higher among
0
100
200
300
400
500
600
700
2004/2005 2005/2006 2006/2007 2007/2008 2008/2009
Other leisure time Afterschool
educational time Screen time
Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls
Figure 1 Median (minutes/day) self-reported screen time,
afterschool educational time, and other leisure sedentary
time
Trang 6high-SES adolescents, especially girls, which is in contrast
to that reported among developed countries where higher
SES is associated with lower screen time.51
Similarly, this study also found a negative association
between total nonschool sedentary time and SES, which is
also in contrast with fındings reported by developed
countries.52–54Various explanations are possible for the
higher rates of screen time and total sedentary time
among higher-SES adolescents Higher-SES families may
have greater access to sedentary technologies, their
chil-dren might be more likely to engage in study outside
school hours, and their children might be more likely to
spend time helping with housework
No association was found between screen time or total
nonschool sedentary behavior and physical activity This
fınding supports results of a recent review of the
corre-lates of physical activity in children and adolescents,10
which concluded that there was no relationship between TV/video games and physical activity among those aged 13–18 years Similarly, sedentary time and physical activ-ity have been suggested as being independent behaviors
in school children.18
Strengths and Limitations The strength of this study was its longitudinal design with repeated measures and a good retention rate over the 5-year period (77%) The prospective cohort study design allowed examination of changes in a large variety of sed-entary behaviors and relevant sociodemographic factors during adolescence Another strength of the study was the use of accelerometers to objectively measure seden-tary time In contrast to self-report, accelerometers pro-vide very precise information on movement patterns;
Table 3 Correlates of total sedentary behavior (minutes/day) by gender, mean change (95% CI)
Univariate Adjusted a
Univariate Adjusted a
ADOLESCENT SEDENTARY ACTIVITY QUESTIONNAIRE
Year of follow-up (ref: Year 1—baseline)
Pubertal status (ref: prepubescent)
Maternal education (ref: did not complete junior high school)
SES quartile (ref: 1st—the poorest)
ACCELEROMETER
Year of follow-up (ref: Year 2)
Pubertal status (ref: prepubescent)
Note: SES is based on household wealth index.
a
Adjusted for pubertal status, maternal education, SES, and wearing time (from accelerometry data)
Trang 7however, because accelerometers provide no contextual
information, both methods are required
The fındings showed that irrespective of the
mea-surement instrument, sedentary behavior among
Viet-namese adolescents has increased over time The study
design, a multistage cluster, random sampling of urban
adolescents from Ho Chi Minh City, provides strong
external validity of the results Thus, the results are
likely to be representative of other adolescent
popula-tions in large cities in Vietnam and possibly other
South East Asian cities, which are going through rapid
economic transition
One of the limitations is the substantial amount of
missing accelerometer data, especially in the later survey
years The main reason for the missing data was that
many of the participating adolescents did not comply
with wearing instructions This lack of compliance may
have led to an underestimation of sedentary time
mea-sured by the accelerometer
Similarly, given the large number of prompts in the
questionnaire for various kinds of sedentary behavior, it
seems that total sedentary time might have been
overes-timated by the questionnaire This also would help
ex-plain partly the discrepancy between the accelerometer
and questionnaire However, there is no indication
sug-gesting that such overestimation of sedentary time would
be different across age categories Accelerometer results
also suggested an increase in sedentary time with age,
although a smaller increase than those reported in the
questionnaire
Conclusion
The present study showed an increase in daily nonschool
sedentary behavior among Vietnamese youth as they
progress through adolescence Information on correlates
given can be used to plan evidence-based strategies that
are age-tailored and targeted to differences between
gen-ders, and to risk groups, such as students in
high-SES families Strategies to reduce excessive educational
sitting include more active classes that incorporate
stand-ing time into the educational process, an increase in
re-cess and break times,55,56and active homework.57Other
promising strategies include encouraging adolescents to
switch from passive to active screen time,58,59 and to
exchange sitting and chatting during leisure time with
walking and chatting
Decreasing sedentary behavior has an important
role in prevention strategies aimed at tackling
emerg-ing obesity and chronic diseases in Vietnamese
adoles-cents Intervention strategies in Ho Chi Minh City will
need to have multidisciplinary approaches and
sup-port from a range of communication channels to
in-crease awareness of the positive effects of decreasing sedentary time for both adolescents and their parents
The survey was funded by a grant from the Nestlé Foundation, Switzerland Nguyen H.H.D Trang got the partial PhD schol-arship (The University of Sydney World Scholars and the Hoc Mai Foundation)
No fınancial disclosures were reported by the authors of this paper
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