Physical activity guidelines_and_prescho

PEDIATRIC ORIGINAL ARTICLE
Physical activity guidelines and preschooler’s obesity status
S Vale1
, S Trost2
, JJ Ruiz3
, C Reˆgo4,5
, P Moreira1,6
and J Mota1
AIM: The benefits of promoting physical activity (PA) in counteracting the high prevalence of childhood obesity have become
increasingly important in the past decade. The aim of this study was to examine the association between compliance of daily
PA recommendations and the risk of being overweight or obese in preschool-aged children.
METHODS: The sample comprised 607 children aged 4–6 years, recruited from kindergartens located in the metropolitan area of
Porto, Portugal. Preschooler’s body mass index was classified according to International Obesity Task Force. PA was assessed during
7 consecutive days by accelerometer. Children were classified as meeting or not meeting PA recommendations based on two
guidelines: (i) at least 3 h per day of total PA (TPA); and (ii) at least 1 h per day of moderate to vigorous PA (MVPA).
RESULTS: The prevalence of overweight and obesity was 23.5 and 10.6% in girls and 17.2 and 8.9% in boys. In all, 90.2 and 97.3% of
girls met the X1 h MVPA and X3 h TPA recommendations, respectively. In all, 96.2 and 99.4% boys met the X1 h MVPA and X3 h
TPA recommendations, respectively. Boys were significantly more likely to achieve the X1 h MVPA and X3 h TPA
recommendations than girls (Pp0.001). Not meeting the X1 h MVPA guideline was associated with obesity status (OR: 3.8;
IC: 1.3–10.4), in girls, but not boys. No other statistically significant associations were found.
DISCUSSION: These findings suggest that over 90% of children met the recommended guidelines. There is an association with low
levels of MVPA and higher obesity status among preschool girls. Further, longitudinal studies are needed to confirm these data.
International Journal of Obesity (2013) 37, 1352–1355; doi:10.1038/ijo.2013.109
Keywords: physical activity; preschool children; body fat mass; guidelines; accelerometer
INTRODUCTION
The prevalence of childhood obesity has been rising during the
last two decades. In 2010, the World Health Organization
estimated that globally, 42 million children under 5 years of age
were overweight or obese.1
In Portugal, there is a high prevalence
of overweight and obese children2
and adolescents.3
Patterns of physical activity (PA), sedentary time and nutrition
appear to have an important role in long-term weight regulation.4
In addition, it has been suggested that sedentary time during the
first decades of life is linked to several health-related risks during
adulthood.5
Hence, the benefits of reducing sedentary lifestyle
and promoting PA have become increasingly important for public
health.6,7
Moreover, childhood and adolescent overweight
is strongly associated with adult obesity.8,9
Recent PA guidelines from UK, Australia and Canada recom-
mend that preschool children accumulate at least 3 h of PA
across an entire day.10–12
In addition, the Canadian guidelines
recommended that preschool children accumulate at least 1 h of
moderate to vigorous PA (MVPA) daily.12
The accurate assessment
of PA is extremely important when examining the relationships
between PA and health. Accelerometry has become a commonly
used and accepted measure of PA and is the preferred method
over the last decade on epidemiological studies in young children.
However, relatively few studies have examined the association
between PA and obesity status in preschool children13–17
and to
the best of our knowledge, no studies have compared the
compliance of daily PA recommendations and obesity status in
this age group.
Therefore, the purpose of this study was to determine
compliance with current PA guidelines in Portuguese preschool
children and examine the association between meeting daily PA
recommendations and weight status.
MATERIALS AND METHODS
Participants and data collection
This was a cross-sectional study completed in kindergartens enrolled in the
Preschool PA, Body Composition and Lifestyle Study (PRESTYLE), a
longitudinal study that began in autumn 2008. All kindergartens located
in the metropolitan area of Porto were invited to participate. Of those
accepted, 20 classrooms were selected. All children belonging to
the selected classrooms were invited to participate. A random sample of
1160 children, aged 2–6 years, was recruited from kindergartens located in
the metropolitan area of Porto, Portugal. In this study, we included only
children aged 4 to 6 years old who had 7 complete days of accelerometer
data and had height and weight information. The final sample included
607 healthy preschool children (48.5% girls). Data collection took place
between April 2009 and November 2010.
Informed written consent was obtained from parents and school
supervisors. Study procedures were approved by the Portuguese Founda-
tion for Science and Technology and by the Scientific Board of Physical
Activity and Health PhD program.
Anthropometric measures
Body mass and height were measured by standard anthropometric
methods. Body mass was measured to the nearest 0.10 kg, with
participants lightly dressed (underwear and t-shirt) using a portable digital
1
Research Centre in Physical Activity, Health and Leisure (CIAFEL), Faculty of Sports of University of Porto - FADEUP, Porto, Portugal; 2
School of Human Movement Studies.
University of Queensland, Brisbane, Australia; 3
Department of Physical Education and Sport, School of Sport Sciences, University of Granada, Granada, Spain; 4
Faculty of Medicine,
University of Porto, Porto, Portugal; 5
Children and Adolescent Centre, CUF Hospital, Porto, Portugal and 6
Faculty of Nutrition, University of Porto, Porto, Portugal. Correspondence:
Dr S Vale, Research Centre in Physical Activity, Health and Leisure (CIAFEL), Faculty of Sports, University of Porto, FADEUP, R.Plaćido Costa, 91, Porto 4200 450, Portugal.
E-mail: susanavale@hotmail.com
Received 23 March 2013; revised 3 May 2013; accepted 20 May 2013; accepted article preview online 12 June 2013; advance online publication, 2 July 2013
International Journal of Obesity (2013) 37, 1352–1355
& 2013 Macmillan Publishers Limited All rights reserved 0307-0565/13
www.nature.com/ijo

scale (Tanita Inner Scan BC 532, Tokyo, Japan). Height was measured to the
nearest millimetre in bare or stocking feet with children standing upright
against a Holtain portable stadiometer (Tanita). The measurements were
repeated twice and the average was recorded. Body mass index was
calculated as body mass (kg) divided by height (m) squared and was
classified according to the International Obesity Task Force.18
Physical activity
Daily PA was measured using the ActiGraph GT1M accelerometer,
(Pensacola, FL, USA). This accelerometer provides output in activity counts,
which gives information about the intensity of PA.19
Alternatively,
accelerometer output can be interpreted using specific cut-points, which
identify time in different intensities of PA. Data reduction, cleaning and
analyses of accelerometer data were performed using a specially written
program described and used previously.20,21
Data were analysed using
specific pediatric cut-points, which have been validated for young children:
X101 c.p.m. for active time (total PA time (TPA)) and X1680 c.p.m. for
moderate to vigorous PA.22–24
For the purpose of this study, the epoch duration or sampling period
was set to 5 s, which is more accurate for the spontaneous and intermittent
activities of children as used previously with a similar sample.25
A minimum of 10 h of data per day was required for analysis. Parents
were instructed to attach the accelerometer when the child awoke and to
remove it when they went to bed. The accelerometer was worn snuggly
under clothing on the child’s hip using a fully adjustable elastic waist belt.
For TPA, we followed the guidelines of UK recommendations, Australian
National Physical Activity Recommendations for children 0–5 years and
Canada´ recommendations,10–12
calculating the proportion of children who
spent at least 3 h per day active, (X3 h TPA). For MVPA, we calculated the
proportion of children who spent at least 1 h per day (X1 h MVPA).12
Parental education
Parents’ education was used as a proxy measure of socioeconomic status
because it is known that education is positively associated with more
health-related knowledge26
and a higher capacity to put it into practice.27
It was defined as the highest level of education from mother or father,
respectively. In mono-parental families, the parental education was based on
the children’s principal guardian. Parents’ education was based on the
Portuguese Educational system a 9 years’ education or less sub secondary
level (scored as 1), 10–12 years’ education-secondary level (scored as 2) and
higher education (scored as 3). Levels 1, 2 and 3 were considered as low,
middle and high education.28
Parental education was negatively associated
with daily patterns of PA and guidelines compliance.29
Statistical analyses
Means and s.d.’s were calculated to describe children’s characteristics by
sex. The comparisons between compliance with daily PA recommenda-
tions (Meet versus No Meet) were first evaluated by w2
test and
independent t-test. For each sex, the association between weight status
and compliance with daily PA recommendations was examined using
multinomial regression analysis. Each model was adjusted for age and
parental education. Statistical analysis was performed using the SPSS 18.0
software (SPSS Inc., Chicago, IL, USA). The level of significance was set
at alpha level of 0.05.
RESULTS
Table 1 shows descriptive statistics for the PA outcomes by sex.
Boys had higher TPA and MVPA than girls (Pp0.001).
No significant sex differences were found with regard to body
mass index.
Among girls, the prevalence of overweight and obesity was 23.5
and 10.6%, respectively. In comparison, the prevalence of over-
weight and obesity among boys was lower at 17.2 and 8.9%,
respectively; however this difference was of only marginal
statistical signficance (P ¼ 0.082). Compliance with PA recommen-
dations was significantly higher among boys than in girls. In all,
90.2 and 97.3% of girls met the X1-h MVPA and X3-hTPA
recommendations, respectively. In comparison, 96.2 and 99.4% of
boys met the X1-h MVPA and X3-h TPA recommendation,
respectively (Figure 1).
Multinominal regression analysis showed that overweight and
obese girls were approximately four times more likely to not meet
the X1-h MVPA than their non-overweight counterparts. No other
statistically significant associations were found for the variables
under study (Table 2).
DISCUSSION
This study aimed to document compliance with guidelines among
Portuguese preschool children and examine the association
between compliance of daily PA and MVPA recommendations
and obesity status. The key point of this study was that over 90%
of children met the recommended guidelines.
The findings show that, in girls as young as 4–6 years, low daily
MVPA was associated with obesity status. This highlights the
potentially important role of daily MVPA in the prevention and
maintenance of weight status in young girls.
Previous investigations have examined the association between
weight status and PA in preschool children. Several cross-sectional
studies observed that overweight or obese preschool children
have lower PA levels than the normal-weight peers.14,30,31
One
study found that children with low-vigorous PA were more likely
to be classified as overweight or obese compared with those with
high-vigorous PA.16
In a longitudinal study using a Caltrac
accelerometer, 103 US children aged 3 to 5 years were
measured annually during 8 years. The study found that the
Table 1. Sample characteristics
Total
(n ¼ 607)
Girls
(n ¼ 170)
Boys
(n ¼ 172)
P-value
Age 5.1±0.8 5.0±0.8 5.1±0.8 0.064
Weight 21.1±4.1 20.8±4.0 21.3±4.2 0.142
Height 111.2±7.5 110.2±7.4 112.1±7.5 p0.05
BMI 16.9±2.0 17.1±2.0 16.9±2.0 0.226
TPA (min per week) 295±51 286±50 303±51 p0.001
MVPA (min per
week)
96±26 89±23 103±27 p0.001
Abbreviations: BMI, body mass index; X2 h TPA, at least 2 h total physical
activity per day each day a week; X3 h TPA, at least 3 h total physical
activity per day each day a week; X1 h MTPA, at least 1 h moderate to
vigorous physical activity per day each day a week. Bold text indicates
significant P values.
97.3 99.4
≥3hTPA
2.7 0.6
9.8
96.2
3.8
Meet No meet
Girls
Meet No meet
Boys
Meet No meet
Girls
Meet No meet
Boys
p=0.003p=0.141
≥1hMVPA
90.2
Figure 1. Prevalence of children that met the recommendations in TPA at least 3 h per day; MVPA at least 1 h per day, by gender.
Physical activity and childhood obesity
S Vale et al
1353
& 2013 Macmillan Publishers Limited International Journal of Obesity (2013) 1352 – 1355

final sum of skinfolds was negatively associated with PA over the
follow-up period.32
Likewise, in US children, a 3-year follow-up of 4
to 6 years old children showed that higher overall PA, vigorous PA
and 5-min bouts of vigorous PA were associated with lower
quartile %BF (follow-up).33
Thus, our findings for girls support the
hypothesis that higher levels of habitual PA might have a
protective role against higher levels of adiposity, even in young
ages.34
The null findings observed among boys is difficult to
explain. A possible explanation for the differences among sexes
may be that our data also showed that girls had higher obesity
rates than boys (Pp0.001), which is consistent with most studies
of preschool children.35
Our study found that overall, 98.4 and 93.3% of the children
met, respectively, the X3 h TPA and X1 h MVPA recommenda-
tions. On average, boys were more likely to achieve the
recommendations than girls. These results are difficult to compare
with other studies because, to the best of our knowledge, no
previous study has assessed compliance with current PA
recommendations and obesity status in these ages. In this sense,
our findings are novel and further studies are needed to
understand which of the recommendations better suit health
indicators.
PA has an enormous potential and should be recognized
as a fundamental public health constituent and main factor of a
healthy lifestyle. Some recommendations state that children do
not need to do PA all at once. It can be accumulated throughout
the day, and can include light activity like standing up, moving
around and playing. So, there is a need to recognize the factors
that influence PA in preschool children and to learn how to help
them to be more active. So, we believe that the determination of
evidence-based PA guidelines to inform public health profes-
sionals, health policy, educators and for knowledge translation to
the general public is crucial.
The strengths of this study include: our focus on PA levels in
preschool children; an assessment of compliance with
PA recommendations using an objective PA measure,
although it should also be recognized that accelerometers are
unable to detect some activities such as swimming and cycling.
The 5-s epoch used in this study appears to capture a greater
amount of data in preschool children.25
Nevertheless,
some limitations of the study should be recognized. The study
included preschool children from only one metropolitan area,
which makes it difficult to generalize the findings to other
samples. Further, because the study was cross-sectional, it is
not possible to infer causal relationships using such a cross-
sectional design.
CONCLUSION
The present study showed that over 90% of children met the
recommended guidelines for PA. Among girls, failure to meet the
daily recommendation for MVPA was associated with obesity
status. Longitudinal studies are needed to confirm these findings.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
ACKNOWLEDGEMENTS
We thank the children, their parents, as well as the staff from the all kindergartens.
This study was supported in part by grants: Portuguese Foundation for Science and
Technology—SFRH/BPD/81566/2011, PTDC/DES/098309/2008, PEst-OE/SAU/UI0617/
2011 and Spanish Ministry of Science and Innovation—RYC-2010-05957.
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