Content uploaded by Alicia Fedewa
Author content
All content in this area was uploaded by Alicia Fedewa on Aug 25, 2014
Content may be subject to copyright.
A Meta-analysis of the Relationship Between Children’s Physical
Activity and Mental Health
Soyeon Ahn,
1
PHD, and Alicia L. Fedewa,
2
PHD
1
Department of Educational and Psychological Studies, University of Miami, and
2
Department of Educational,
School, and Counseling Psychology, University of Kentucky
All correspondence concerning this article should be addressed to Soyeon Ahn, PHD, 5202 University Dr.,
Merrick Building #305-9, Coral Gables, FL, 33146, USA. E-mail: s.ahn@miami.edu
Received May 28, 2009; revisions received October 24, 2010; accepted October 31, 2010
The present study was a comprehensive, quantitative synthesis of the literature examining the effects of physi-
cal activity on children’s mental health outcomes. The final analysis included 73 published and unpublished
studies, totaling 246 effect sizes. Various study and participant characteristics were coded to assess moderator
effects, including type of physical activity, mental health outcome, gender, cognitive ability, mental status, and
implementer of the physical activity, etc. Results demonstrated varying effects depending on the methodology
of the examined study [i.e., correlational vs. randomized controlled trial (RCT)/non-RCT] and characteristics
of the participants, although overall effects of physical activity on children’s mental health were small but
significant, indicating that on average physical activity led to improved mental health outcomes for all children.
Key words interventions; mental health; overweight; physical activity.
Introduction
Within the past decade, the US has seen a steady decline in
the numbers of physically active children (Centers for
Disease Control [CDC], 2008). Although children spend
the majority of the day in classrooms, schools are increas-
ingly under more pressure to meet high stakes testing
standards. This pressure has created the push for more
instructional time and less time devoted to physical activity
(i.e., physical education or recess breaks; Burgeson,
Weschler, Brener, Young, & Spain, 2001; Hardman,
2008). Moreover, technology has afforded children more
opportunities to play video games, watch TV, or browse the
Internet, activities that contribute to sedentary behaviors
(Stevens, To, Stevenson, & Lochbaum, 2008). Parents
also report having more concern about their children’s
safety in playing outside or using active means of trans-
portation (i.e., biking, walking) on their way to school,
further limiting the amount of children’s physical activity
(Stevens et al., 2008; World Health Organization [WHO],
2009).
When physical activity is restricted during school
hours, children do not compensate for loss of physical
activity after school, resulting in children who are incredibly
sedentary throughout the majority of the day (Dale, Corbin,
& Dale, 2000). The relationship between sedentary behav-
iors and prevalence of obesity has been well documented
(CDC, 2008; Pate et al., 2002). For the first time in history,
children have a shorter lifespan than their parents due
to obesity-related diseases (Wang & Veugelers, 2008;
WHO, 2009). Although, but one factor in a myriad of influ-
ences, the amount of physical activity children engage in is
linked to their status of being overweight or obese (National
Center for Health Statistics, 2009).
One critical relationship that has been examined in the
literature has been the link between physical activity and
mental health. Although the research in this area is scarce
compared to studies examining the effects of physical ac-
tivity on mental health in adults, there is a considerable
need for this body of research. Approximately 20% of
school-age children have a diagnosable mental health
Journal of Pediatric Psychology pp. 1–13,2011
doi:10.1093/jpepsy/jsq107
Journal of Pediatric Psychology ßThe Author 2011. Published by Oxford University Press on behalf of the Society of Pediatric Psychology.
All rights reserved. For permissions, please e-mail: journals.permissions@oup.com
Journal of Pediatric Psychology Advance Access published January 11, 2011
by guest on January 12, 2011jpepsy.oxfordjournals.orgDownloaded from
disorder and require psychological treatment (U.S. Public
Health Service, 2000). However, the majority of children
do not receive services to remediate their concerns
(Thompson, 2005; U.S. Public Health Service, 2000).
One subset of the childhood population that is particularly
at risk for mental health disorders are those children clas-
sified as overweight or obese. It is well documented in the
literature that children who are classified as overweight or
obese have significantly more psychosocial problems than
do children who are of typical weight (Farhat, Iannotti, &
Simons-Morton, 2010). Yet, when studies examine the
effects of physical activity on children’s mental health,
differential effects for children who are either overweight
or obese are commonly not considered. Although physical
activity interventions that have been used to build
self-esteem and physical fitness in youth have exhibited
promising results (Ekeland, Heian, & Hagen, 2005), it is
unclear what the impact of physical activity has on the
mental health of all children, including those who are
considered overweight or obese.
In a meta-analysis of 16 randomized controlled stud-
ies, Larun and colleagues (Larun, Nordheim, Ekeland,
Hagen, & Heian, 2006) investigated the effects of vigorous
exercise interventions in preventing or reducing anxiety or
depression in children and youth. Although depression
and anxiety were the only outcome variables in this
meta-analysis, results were in favor of exercise interven-
tions in alleviating or preventing negative symptoms in
children and youth (Larun et al., 2006). Although the
2006 meta-analysis by Larun and colleagues was a compre-
hensive synthesis of the literature with respect to the out-
comes of anxiety and depression symptomology in youth,
there are a number of other mental health concerns that
affect school-aged populations. Attention-deficit hyperac-
tivity disorder (ADHD) is typically a comorbid condition
in children with such diagnoses as anxiety or depression,
and there have been a handful of studies investigating the
relationship between physical activity and mental health
outcomes in children diagnosed with ADHD. In addition,
self-esteem has been found to be an important buffer in the
onset of childhood mental disorders (Ekeland et al., 2005);
it is therefore imperative to consider the role of self-esteem
in relation to physical activity and children’s mental health.
Including these studies in the meta-analysis would
have provided researchers a more comprehensive picture
of the relationship between physical fitness and mental
health in children. Further, the 2006 meta-analysis
excluded studies that were not randomized controlled clin-
ical trials, leaving open the question as to whether effects
have been found in other studies, including quasi-
experimental and correlational designs. Last, Larun and
colleagues (2006) excluded children who were classified
as overweight or obese and therefore did not take into
account children’s health status. It is important to consider
the differential effects physical activity may have on chil-
dren’s health status, especially considering the docu-
mented risk of overweight/obese children with increased
psychosocial difficulties (Farhat et al., 2010).
Given the number of studies that were not included in
the 2006 meta-analysis, as well as the multitude of other
mental health concerns pervasive in youth not taken into
account, this study attempted to fill the gap in examining
the relationship between physical activity and children’s
mental health. Moreover, a comprehensive set of modera-
tor variables were also examined. No meta-analysis to
date has examined differential effects of moderator vari-
ables in the relationship of physical activity and mental
health in children, although there is reason to believe
that intervention effects of physical activity may differ
depending on such moderators as gender (Kremers,
Droomers, Van Lenthe, & Brug, 2007; Simen-Kapeu &
Veugelers, 2010), age (Fedewa & Ahn, in press; Kremers
et al., 2007), methodological design (Conn, 2010), and
implementer (Stice, Shaw, & Marti, 2006), to name a
few. Researchers have argued for the increased use of mod-
erator analyses in examining outcomes of physical inter-
ventions in children given the multitude of differential
relationships and mechanisms of behavior change in
youth (Kremers et al., 2007). Thus, a number of moderator
analyses were conducted to determine if child mental
health outcomes were associated with various charac-
teristics of samples, research methodology, or interven-
tions. Therefore, the present meta-analysis addressed the
following two questions:
1. What are the overall effects of physical activity on
children’s mental health?
2. Do the effects of physical activity on children’s
mental health vary depending on the intervention,
sample, and study design characteristics? In partic-
ular, is physical activity more important for chil-
dren who are classified as obese or overweight?.
Methods
The Search Process
The location of relevant studies in this research synthesis
was as exhaustive as possible, and included both published
and unpublished literature based on a manual as well as a
computerized search of pertinent databases including
PsychLit, PsychInfo, Dissertation Abstracts, MedLine, and
ERIC. Key terms for literature searches included the words
2Ahn and Fedewa
by guest on January 12, 2011jpepsy.oxfordjournals.orgDownloaded from
‘‘physical activity,’’ ‘‘physical fitness,’’ ‘‘physical exercise,’’
‘‘curricular activity,’’ ‘‘exercise,’’ ‘‘mental health,’’ ‘‘anxiety,’’
‘‘depression,’’ ‘‘dysthymia,’’ ‘‘bipolar,’’ ‘‘post-traumatic stress
disorder,’’ ‘‘attention deficit hyperactivity disorder,’’ ‘‘eating
disorder,’’ ‘‘anorexia,’’ ‘‘bulimia,’’ ‘‘youth,’’ ‘‘adolescents,’’
and ‘‘children’’. As well as database resources, general
search engines (e.g., Google) were employed with the
above key terms to capture those studies that had not
been included in the databases. Lastly, literature reviews,
ancestry searches, and comprehensive analyses conducted
in the area (i.e., Jorm, Allen, O’Donnell, Parslow, Purcell,
& Morgan, 2006; Larun et al., 2006; Ortega, Ruiz, Castillo,
& Sjostrom, 2008) were searched to include any additional
bibliographic information. Results yielded over 150 refer-
ences between 1960 and 2010.
Studies retrieved from the initial searches were
screened using specific criteria: (a) studies had to investi-
gate the effect or relationship of some type of physical
activity and children’s mental health (i.e., the dependent
variable was a mental health outcome of some form);
(b) target populations had to range from pre-school to
high-school age (3–18 years); (c) no qualitative or concep-
tual studies were included; (d) data that have only been
used once in a manuscript to avoid replication (i.e., studies
that had published more than one article on the same
participants were not included, as were studies that were
done as unpublished theses and subsequently published);
and (e) studies must have been reported in English. This
process identified a total of 95 studies.
Out of 95 studies, 22 studies (a reference list of 22
excluded studies is available online as Supplementary
Data) were excluded due to the following reasons: (a) 20
studies did not provide sufficient information (i.e., mean,
standard deviation) for calculating effect size and (b) two
studies used advanced data analysis techniques such as
regression. Therefore, a total of 73 studies (a reference
list of 73 included studies is available online as
Supplementary Data) were included in the current research
synthesis.
Coding of Studies
Based on a literature review, a systematic coding scheme was
developed to identify salient features of each study.
Specifically, variables with regard to (a) study design,
(b) participant, (c) physical activity/exercise, and
(d) mental health characteristics were independently
coded and entered into the computer database for statistical
analyses. Coding of these variables was mainly based on
author’s report. When no information was given by
author(s), variables were coded as ‘‘not informed.’’ The
author and a graduate student independently coded and
entered variables described above. All discrepancies were
resolved upon discussion.
Study Design Characteristics
Study design was coded as (1) between-subject design
(i.e., posttest-only-control group design), (2) within-subject
design (i.e., pretest–posttest design), (3) mixed-design
(i.e., pretest–posttest control group design), and (4) cross-
sectional or correlational design. Based on the research
questions being asked, the included studies were catego-
rized into either (a) group comparison study examining
the effect of physical activity interventions on mental
health outcomes or (b) cross-sectional/correlational study
examining the relationship between physical activity and
mental health outcomes.
When comparison groups were used, the assignment
methods that allocate subjects into comparison groups
were categorized into the following areas: (a) random,
(b) not random, and (c) not informed. Then, studies
using random assignment were next categorized as ran-
domized controlled trials (RCTs), which were compared
to the rest of studies (i.e., non-RCTs). Study setting was
coded as (1) school, (2) clinic, (3) after-school program,
(4) research center, and (5) other. Last, other study char-
acteristics such as publication type (i.e., published vs.
unpublished) and study location (i.e., US vs. non-US)
were coded.
Participant Characteristics
Participants were coded as (1) typical/typical inferred, (2)
cognitively impaired, (3) learning disabled or children with
academic delays, (4) children with ADHD, (5) children
with Post-Traumatic Stress Disorder (PTSD), (6) children
with emotional problems (e.g., anxiety, depression), (7) chil-
dren with behavior problems (including children with con-
duct disorder), (8) children who had undergone cancer
treatment, and (9) not informed. Participants were also
coded as (1) typical, (2) fit, (3) mixed, and (4) not informed,
depending on their physical fitness status. Other informa-
tion including whether participants were diagnosed or not
(i.e., Yes or No), mean age and gender (i.e., male, female, or
mixed) were also coded.
Physical Activity Characteristics
Specific characteristics of physical activity were coded.
First, the focus of physical activity was qualitatively collect-
ed and then categorized into (1) aerobic training, (2) resis-
tance/strength/circuit training, (3) flexibility training, (4)
regular PE program, (5) sport participation such as ski,
football, and volleyball, (6) movement/motor skill training,
(7) yoga (including meditation), (8) combined, and (9) not
Meta-analysis of Physical Activity 3
by guest on January 12, 2011jpepsy.oxfordjournals.orgDownloaded from
informed. These categories were constructed based on the
description provided by the authors of the study, as well as
the features of the activity children were receiving. If two
categories overlapped (i.e., if aerobic training and resis-
tance training were both targeted for the intervention),
then the study features were coded as a ‘‘combined’’ inter-
vention. The exception to this coding scheme was for the
category of PE intervention, as it was often unclear what
the focus of the PE intervention focus was with respect to
the type of physical activity. Thus, studies using PE pro-
gramming as their physical activity intervention received a
coding of ‘‘PE intervention,’’ even if the PE intervention
may have included aerobic training. The authors chose this
coding framework to maintain consistency across studies,
as the majority of PE programming interventions did not
explicitly state the target of their physical activity. Second,
total hours, frequency per week, intensity (i.e., light, mod-
erate, intense, and mixed when different levels of intensity
were involved), and unit (i.e., individual-based, small
group with less than 10 subjects, medium group with sub-
jects between 10 and 30, large group with more than
30 subjects, and whole class) of the physical activity
were collected. Last, the administrator who led the physical
activity (i.e., teacher/instructor, researcher, PE specialist,
external instructor including after-school counselors, vol-
unteers, after-school counselors, and recreational therapist)
was also coded.
Mental Health Outcome Characteristics
Mental health outcome measures were categorized into de-
pression/dejection, anxiety, global self-esteem, self-concept
(including exercise self-concept, physical self-concept, ac-
ademic self-concept, social self-concept, and family/home
self-concept), distress/PTSD and emotional distress, psy-
chological distress or a combination of multiple symptoms
(e.g., depression and anxiety; emotional disturbance),
suicidal ideation, ADHD, life satisfaction, somatic symp-
toms, problems in social functioning, conduct/behavioral
problems, cognitive impairment, and psychosis.
Effect Size
Depending on the research questions and/or designs of the
included study, the following two types of effect sizes (ESs)
were computed in the current meta-analysis: one for com-
parison studies (d) and the other for correlational/
cross-sectional studies (r). From the comparison studies,
the standardized mean difference between treatment/inter-
vention and control groups was computed. The group with
no physical activity intervention was treated as a control
group. When studies used a pretest–posttest control group
design, dwas computed using the formulas in Morris
(2008). If no pretest was used, dwas computed using
the formula in Lipsey and Wilson (2001). When no suffi-
cient statistics were reported, dwas computed from the
reported tor Fstatistics using the formulas outlined in
Rosenthal (1994). Also, the odds ratio was converted to
dusing the formula presented in Borenstein (2009). From
the correlational studies examining the association between
physical activity and mental health outcome, the reported r
was obtained. In addition, if comparison studies examined
the relationship of physical activity level with mental health
outcome, d-ESs were converted to rby the formulas shown
in Rosenthal (1994).
Statistical Analyses
The statistical analyses were based on the methods pro-
posed by Hedges and Olkin (1985) and also described in
Cooper, Hedges, and Valentine (2009). Under the
fixed-effect model, the computed effect-sizes were weighted
by the inverse of its variance, and an overall homogeneity
test of these effects (Qtotal) was initially performed. When
the fixed-effects model did not hold (or Qtotal was signifi-
cant), the random-effects model or mixed-effects model
with predictors were applied. The random-effects model
incorporated the additional uncertainty to the effect vari-
ances, which was estimated using the methods of mo-
ments. Further, the mixed-effects model with moderators
(i.e., children’s mental health outcomes) incorporated ad-
ditional uncertainty within each level of categorical mod-
erators, whose weights were computed for effect in each
level of moderators. More details about random-effects or
mixed-effects models with categorical moderators can be
found in Raudenbush (2009).
Dependency
Studies often provided dependent effect sizes by using
multiple measures of variables, which in turn violates the
assumption of independence (Glesser & Olkin, 2009).
For instance, Allison et al. (2005) used three mental
health outcomes including psychological distress, prob-
lems in social functioning, and depression/anxiety. Such
dependency issues can be handled in various ways
(Becker, 2000).
In this meta-analysis, the issue of dependency was first
handled by choosing effect sizes from the total score or
averaging effect sizes from subtest scores if no total score
was presented, rather than using a subtest score. Effect
sizes were then grouped into subcategories of physical ac-
tivity and mental health measures described above and
thus they were no longer dependent within each subcate-
gory for the computation of the overall effect sizes. The
authors chose this method due to its simplicity and
4Ahn and Fedewa
by guest on January 12, 2011jpepsy.oxfordjournals.orgDownloaded from
feasibility as compared to multivariate methods, which re-
quire a full variance-covariance matrix of dependent effect
sizes.
Results
Description of Studies
The included 73 studies yielded a total of 246 ESs. These
included 182 d- and 64 r-ESs. Studies were published
between 1974 and 2009 and most of the studies (s¼55)
were conducted in the US, while the rest of them were
from various countries including Brazil (s¼1), German
(s¼1), Hungary (s¼1), South Africa (s¼3), Switzerland
(s¼1), the UK (s¼6), China (s¼2), Canada (s¼4), and
Australia (s¼2). Sample sizes used in the 73 studies
ranged from 9 to 14,594 (M¼484.13, SD ¼1714.82),
including 14 to 502 (M¼55.67, SD ¼86.86) from RCT
(s¼30), 9 to 2,444 (M¼192.85, SD ¼502.27) from
non-RCT (s¼24), and 35 to 14,594 (M¼1398.58,
SD ¼3441.39) from correlational studies (s¼19).
Participants’ age ranged from 3.67 to 17.66 years
(M¼12.67, SD ¼2.94). In the majority of studies, chil-
dren were typical in their mental, fitness, and diagnostic
status (i.e., represented non-clinical populations).
Publication Bias
The current review included both unpublished and pub-
lished studies. However, the Egger’s regression tests
(Sutton, 2009) were found to be significant for both
effect sizes (t(180) ¼1.34, p< .01 for d-ESs;
t(62) ¼1.60, p¼.02 for r-ESs), indicating the presence
of potential publication bias.
Comparison Studies
A total 182 d-effect sizes examining the intervention
effect of the physical activity on children’s mental out-
comes were first analyzed. The significant Q-statistic
of 1395.11 indicates that the included d-ES were hetero-
geneous. Further, the estimated d-ES under the random-
effects model was 0.38 with a SE of 0.11, which was
statistically significant. Such a significant but negative
result indicates that physical activity has a moderate
effect on alleviating children’s negative mental health
outcomes.
However, a statistically significant mean d-ES differ-
ence was found between RCT and non-RCT studies
(Qð1Þ¼65:58,p<:01), showing significantly lower
mean d-ES from RCT studies (
d¼:30,SE ¼0:06)
when compared to non-RCT studies (
d¼:57,
SE ¼0:24). Also, the statistically significant Qstatis-
tics suggested that d-ESs for both studies were
statistically different (Qð101Þ¼298:68,p<:01for RCT;
Qð78Þ¼1030:80,p<:01 for non-RCT). Thus, the follow-
ing moderator analyses were performed separately for
RCTs and non-RCT studies. Table I shows the results
from the RCT and non-RCT studies.
Type of Mental Health Outcome
The intervention effect of the physical activity program
significantly differed by type of mental health outcome
for both RCT (Qð11Þ¼133:67,p<:01) and non-RCT
studies (Qð11Þ¼181:23,p<:01). From RCT studies,
the physical activity intervention was found to be effec-
tive for reducing depression (
d¼:41,SE ¼0:13),
anxiety (
d¼:35,SE ¼0:18), psychological distress/
PTSD (
d¼:61,SE ¼0:30), and emotional disturbance
(
d¼:33,SE ¼0:17). It was also found that physical
activity significantly enhanced children’s self-esteem
(
d¼:29,SE ¼0:08) and their self-concept (
d¼:16,
SE ¼0:10). However, the treatment effect from non-RCT
studies was significant only for increasing children’s
self-esteem (
d¼:78,SE ¼0:28).
Physical Activity Intervention
From both RCT and non-RCT studies, the estimated
mean ESs were significantly different depending on the
characteristics of the physical activity programs, including
focus, intensity, intervention unit, total hours, frequency
per week, and administrator of the physical activity
intervention.
First, the mean d-ESs from RCT studies were statis-
tically significant and largest when the intervention
was focused exclusively on circuit training (
d¼:72,
SE ¼0:29), followed closely by the intervention with a
combined physical activity focus (
d¼:57,SE ¼0:11).
These results indicate that interventions with a focus on
circuit training or a combination of aerobic and resistance
training significantly lowered children’s mental health dis-
turbances when compared to a control group with no phys-
ical activity. From non-RCT studies, the intervention with
sport participation was the sole program that showed a
statistically significant reduction on children’s mental
disturbance, compared to control groups with no physical
activity (
d¼1:06,SE ¼0:27).
Second, an intervention with an intense level of
physical activity was found to be significant for reducing
children’s mental health disturbance from RCT studies
(
d¼:27,SE ¼0:08), although the largest and most
significant intervention effect was found from RCT studies
that did not indicate the intensity level of their physical
activity intervention (
d¼:41,SE ¼0:10). From
non-RCT studies, a moderate intensity of physical activity
Meta-analysis of Physical Activity 5
by guest on January 12, 2011jpepsy.oxfordjournals.orgDownloaded from
Tab le I . Moderator Analyses for d-Effect Sizes
RCT studies Non-RCT studies
k M SE Qwithin K M SE Qwithin
Outcome Q(11) ¼133.67** Q(11) ¼182.23**
Depression 14 0.41** 0.13 32.19** 16 1.14 0.71 94.19**
Anxiety 16 0.35* 0.18 69.96** 9 1.51 0.85 27.16**
Self-esteem 26 0.29** 0.08 60.71** 16 0.78** 0.28 163.25**
Distress/PTSD 5 0.61* 0.30 13.83** 7 1.42 1.15 36.01**
Emotional disturbance 4 0.33* 0.17 7.10 5 0.42 0.41 4.53
ADHD 5 0.92 0.64 17.17** 2 0.31** 0.10 6.09*
Somatic symptom 3 0.35 0.21 1.14 4 0.43 0.40 6.26
Social function problem 11 0.26 0.15 27.48** 6 1.15 0.93 439.63**
Conduct problem 6 0.00 0.46 2.20 6 0.12 0.63 48.99**
Cognitive problem 2 0.50 0.66 6.54* 1 0.82 2.77 -
Self-concept 9 0.16** 0.10 11.59 6 0.12 0.31 16.22**
Quality of life 2 0.15 0.09 0.04 1 0.79 0.9 -
PA focus Q(4) ¼44.21** Q(6) ¼145.22**
Aerobic 30 0.14 0.09 48.51* 48 0.75 0.38 226.17**
Circuit/Strength 9 0.72* 0.29 9.57 3 0.32 0.33 1.16
Flexibility 34 0.13 0.11 95.53** 10 0.69 0.39 111.72**
Combined focus 29 0.57** 0.11 100.86** 3 0.27 0.37 46.55**
Sport participation 1 0.11 51.06** 0.27 17.57**
Yoga/Meditation 10.99 – –
Not indicated – – – – 9 0.32 0.27 482.46**
Intensity Q(4) ¼32.96** Q(4) ¼35.21**
Light 5 0.10 0.29 0.111 3 0.34 0.40 5.82
Moderate 7 0.18 0.17 3.018 3 1.89* 0.90 7.97
Intense 26 0.27** 0.08 36.35 23 0.22 0.41 138.77**
Mixed 13 0.06 0.18 5.31 12 1.44 0.87 36.61**
Not indicated 52 0.41** 0.10 220.93** 38 0.49 0.31 806.46**
Unit Q(4) ¼22.69** Q(4) ¼57.35**
Individualized – – – – 7 1.82** 0.65 17.01**
Small group (<10) 8 0.10 0.21 1.24 3 0.50** 0.14 1.16
Medium group (10–30) 26 0.13 0.08 33.69 6 1.73 1.67 28.59**
Large group (>30) 14 0.38 0.21 34.82** – – – –
Total class 16 0.45** 0.11 41.32** 7 0.25 1.39 33.01**
Not indicated 39 0.39** 0.10 164.91** 56 0.24 0.17 893.73**
Hours Q(2)¼24.46** Q(2)¼41.11**
Less than 20 hr 53 0.16** 0.04 53.69 25 1.84** 0.59 117.20**
20–33 hr 31 0.42** 0.13 125.61** 11 0.28** 0.08 10.27
More than 33 hr 10 0.55** 0.19 74.07** 17 0.09 0.43 109.27**
Frequency Q(6) ¼60.73** Q(4) ¼51.39**
1210.57** 0.18 108.38** 10 0.81* 0.48 103.85**
2180.37** 0.09 39.13** 1 0.99 – –
3350.09 0.08 58.00** 39 0.60 0.46 197.99**
470.61 0.43 7.8 3 0.32 0.55 1.16
5140.30 0.16 5.58 – – – –
711.19 – – – – – –
Not indicated 7 0.39* 0.45 20.98** 26 0.37 0.25 676.46**
Administrator Q(5) ¼16.28** Q(5) ¼47.19**
Teacher 12 0.36* 0.15 60.66** 48 0.76* 0.35 226.17**
Researcher 37 0.20** 0.08 45.71 3 1.71** 0.65 1.16
PE specialist 9 1.02** 0.33 15.8 10 0.09 0.18 111.72**
(continued)
6Ahn and Fedewa
by guest on January 12, 2011jpepsy.oxfordjournals.orgDownloaded from
showed a significant decrease on negative mental health
outcomes (
d¼1:89,SE ¼0:90), compared to control
groups with no physical activity.
Third, the mean d-ES from RCT studies was negative
and statistically significant for physical activity done in
school with the entire classroom (
d¼:45,SE ¼0:11).
However, the mean d-ESs from non-RCT studies were sta-
tistically significant for individualized physical activity
(
d¼1:82,SE ¼0:65) or small group physical activity
(
d¼:50,SE ¼0:14). Post hoc tests comparing mean
d-ESs from non-RCT studies indicated that the individu-
alized physical activity program appeared to be the most
effective for alleviating negative mental health outcomes
(M
diff
¼1.32, p¼.047).
Fourth, the total hours of the physical activity inter-
vention was categorized into three groups: (a) less than
20 hr, (b) 20–33 hr, and (c) more than 33 hr. These three
categories were created based on the mean hours of
the physical activity or physical education program
(20 hr) and its standard deviation (13 hr). These hours
were distributed over the length of the intervention,
which varied by study design. For RCT studies, the
average length of time for physical activity interventions
was 11.1 weeks (SD ¼3.6), while for non-RCT
studies the mean length was 8.95 weeks (SD ¼4.5).
From RCT-studies, physical activity programs with more
than 33 hr showed a statistically significant reduction
in mental health disturbance (
d¼:55,SE ¼0:21),
followed by 20–33 hr of physical training (
d¼:55,
SE ¼0:21) and less than 20 hr physical activity
(
d¼:55,SE ¼0:21). From non-RCT studies, mean
d-ESs showing an intervention effect with less than 20 hr
(
d¼1:84,SE ¼0:59) or 20–33 hr (
d¼:28,
SE ¼0:08) were significant.
Fifth, the mean d-ES from RCT studies was statistically
significant when the physical activity program was provid-
ed once per week (
d¼:57,SE ¼0:18) and twice per
week (
d¼:37,SE ¼0:21). From non-RCT studies, the
intervention with physical activity provided once per week
showed significantly more effect on decreasing negative
mental health outcomes when compared to the control
group (
d¼:81,SE ¼0:48).
Last, mean d-ESs from RCT studies were significant
when the physical activity program was administered by
Table I. Continued
RCT studies Non-RCT studies
k M SE Qwithin K M SE Qwithin
After-school counselor 7 0.11 0.46 1.35 3 0.08 0.53 46.55**
Not indicated 33 0.41** 0.12 158.77** 5 0.27 0.16 17.57**
Therapist 5 0.10 0.29 0.11 1 0.02 – –
Clinician – – – – 9 0.82 0.78 482.46**
Gender Q(3) ¼33.80** Q(3) ¼49.33**
Female 6 0.41 0.43 7.60 23 1.60* 0.66 245.34**
Male 34 0.55** 0.11 119.79** 13 0.04 0.28 476.73**
Mixed 63 0.19** 0.07 137.48** 4 0.39 0.22 238.25**
Not informed – – – – 2 0.00 0.07 –
Diagnostic status Q(1) ¼59.19** Q(1) ¼25.23**
Yes 23 0.17 0.25 64.28** 30 1.00 0.52 197.13**
No 80 0.07* 0.12 218.03** 49 0.64* 0.27 808.49**
Mental status Q(6) ¼9.46 Q(6) ¼84.03**
Normal 53 0.29** 0.04 179.38** 48 0.27** 0.11 788.97**
Cognitively impaired – – – – 2 2.49* 1.42 18.63**
Learning disabled 20 0.36** 0.07 61.01** – – – –
ADHD 6 0.48 0.27 13.83* 1 0.99 – –
Emotionally disturbed 19 0.11 0.13 17.61* 4 0.37 0.20 3.02
PTSD 1 1.27 – – 11 3.42** 1.17 65.71**
Children w/behavior Problem 1 0.11 – – 2 0.03 0.63 3.33
Not indicated 3 0.16 0.21 1.27 11 0.33 0.63 74.93**
Fitness status Q(1) ¼0.07 Q(1) ¼25.23**
Normal 67 0.29** 0.04 197.13** 56 0.23* 0.11 851.57**
Fit 36 0.27** 0.05 808.49** 4 0.06 0.26 0.71
Note. **p<.01; *p<.05.
Meta-analysis of Physical Activity 7
by guest on January 12, 2011jpepsy.oxfordjournals.orgDownloaded from
the classroom teacher (
d¼:36,SE ¼0:15), researcher
(
d¼:20,SE ¼0:08), or physical education specialist
(
d¼1:02,SE ¼0:33). From non-RCT studies, the
significant treatment effect was found when physical activ-
ity intervention was administered by the classroom teacher
(
d¼:76,SE ¼0:35) and researcher (
d¼1:71,
SE ¼0:65), whose mean d-ESs were not statistical
different (M
diff
¼0.95, p¼.19).
Participant Characteristics
From both RCT and non-RCT studies, significant mean
differences were found by several participant characteristics
including gender and diagnostic status. However, the in-
tervention effect did not depend on age or whether partic-
ipants were on a prescribed regimen of medication. A
significant mean difference by children’s mental health
status and physical fitness status was found only from
non-RCT studies, not from RCT studies.
First, both male and mixed-gender groups from RCT
studies showed significant intervention effects, while only
females from non-RCT studies showed significant interven-
tion effects on alleviating negative mental outcomes.
Second, it was found from both RCT and non-RCT studies
that the physical activity programs were more effective
in reducing negative mental health outcomes for children
who were clinically diagnosed. Third, the overall means
from non-RCT studies varied depending on children’s cog-
nitive and mental health status. In particular, the overall
mean d-ES from the cognitively impaired and PTSD classi-
fied groups showed the largest effects. Post hoc analysis
indicates that the overall mean d-ES for PTSD was signifi-
cantly larger compared to typically developing children
(M
diff
¼2.68, p< .05). Fourth, the intervention effect
was equally effective for children classified as overweight/
obese and children who were of average weight.
Correlational Studies
A total of 64r-ESs represents the relationship between chil-
dren’s level of physical activity and mental health. The
significant Qstatistics of 1040.02 indicates that the 64r-
ESs were statistically different. Under the random-effects
model, the estimated average correlation was statistically
significant, having a weighted mean of 0.06 with a SE
of 0.02. The statistically significant and negative effect in-
dicates that greater physical activity was related to a lesser
likelihood of experiencing detrimental mental health out-
comes. Table II shows the results from correlational/
cross-sectional studies.
Type of Mental Outcome
The overall relationship between physical activity level
and mental health differed depending on the type of
mental health outcome (Qð11Þ¼272:20,p<:01). Of
the 11 types of mental health outcomes, the level of phys-
ical activity showed significant relations to depression
(
r¼:14,SE ¼0:04) and self-concept (
r¼:14,
SE ¼0:05). Such results indicated that the level of phys-
ical activity had a significantly negative relationship
with depression and significantly positive relationship to
a child’s self-concept.
Participant Characteristics
The mean r’s varied by several participant characteristics
including gender, cognitive status, and physical fitness
Tab le I I. Moderator Analyses for r-Effect sizes
Study characteristics K M SE Qwithin Study characteristics k M SE Qwithin
Outcome, Q(10) ¼540.32** Fitness status, Q(3) ¼286.81**
Depression 12 0.14** 0.04 272.2** Typical 23 0 0.05 37.20*
Anxiety 7 0.09 0.06 22.85** Fit 4 0.02 0.02 0.29
Self-esteem 14 0.04 0.04 30.75** Obese 35 0.12** 0.04 174.61**
Distress/PTSD 5 0.04 0.06 73.03** Not indicated 2 0.03 0.15 541.19**
Emotional mood 3 0.09 0.08 18.15** Mental status, Q(2) ¼87.79**
Somatic symptom 3 0.01 0.01 1.65 Typical 60 0.07** 0.03 408.86**
Problem in social function 7 0.04 0.06 32.61** Learning disabled 2 0.04 0.05 2.27
Conduct problem 1 0.19 0.14 Not indicated 2 0.03 0.16 541.09**
Psychosis 2 0.01 0 0.01 Gender, Q(2) ¼43.46**
Self-concept 8 0.14** 0.05 52.6** Girl 13 0.13* 0.06 98.71**
Suicidal ideation 2 0.03 0.1 8.66** Boy 6 0.17* 0.09 31.72**
Diagnostic status, Q(1) ¼1.15 Mixed 45 0.03 0.03 866.13**
Yes 6 0.03 0.09 11.81*
No 58 0.07** 0.03 1027.07**
Note. **p<.01; *p<.05.
8Ahn and Fedewa
by guest on January 12, 2011jpepsy.oxfordjournals.orgDownloaded from
status, but they did not depend upon age or whether chil-
dren were clinically diagnosed. First, both girls and boys
showed significant mean rs between level of physical activ-
ity status and mental health. The magnitude of mean cor-
relations for boys and girls were almost identical. Second,
only children who were typically developing in their cog-
nitive abilities showed a significant but negative relation-
ship of physical activity to mental health. Third, the mean
correlation between physical activity and mental health
outcome for children classified as obese was found to be
statistically significant. Finally, the relationship between
physical activity and negative mental health outcomes
was negative and significant for children who were not
clinically diagnosed.
Other Study Characteristics
For both d- and r-ESs, statistical results from the moderator
analyses using other study characteristics such as setting of
the physical activity intervention and study location are
available online as Supplementary Data.
Discussion
The current study examined the effect of children’s phys-
ical activity on their mental health outcomes. Through a
comprehensive synthesis of the literature, 73 studies yield-
ing 246 effect sizes revealed a number of critical findings.
Some of the findings varied depending on the methodolog-
ical design of the included studies. RCT, non-RCT, and
correlational results will be discussed, highlighting the sig-
nificance and practical implications of these findings.
As predicted, increased levels of physical activity had
significant effects in reducing depression, anxiety, psycho-
logical distress, and emotional disturbance in children.
Both RCT and non-RCT studies also showed that physical
activity increased children’s levels of self-esteem. An overall
effect size of 0.30 for RCT studies and 0.57 for
non-RCT studies is consistent with meta-analytic reviews
in adults, which have found effect sizes that range from
0.36 to 1.10 in both clinical and non-clinical populations
(see Stathopoulou et al., 2006). These results mirror stud-
ies done with adult populations, as physical activity has
shown significant benefits in lowering adult depression,
anxiety, and overall psychological distress (Dixon,
Mauzey, & Hall, 2003; Paluska & Schwenk, 2000). The
2006 meta-analysis using solely randomized controlled
studies with children found similar results with respect
to the small, but beneficial effects of physical activity on
depression and anxiety (Larun et al., 2006).
One of the main purposes of this analysis was to eval-
uate whether physical activity exerted a unique effect
for children who were classified as overweight or obese.
Given that prior research has identified increased psycho-
social distress among children classified as overweight or
obese (Farhat et al., 2010), it was expected that physical
activity may play an even more important role for this
group of children. Both RCT and non-RCT studies, how-
ever, demonstrated equal effects for children who were
obese/overweight and those who were of typical weight.
In other words, both groups of children showed statistical-
ly significant effects on improved mental health, regardless
of their weight/height ratio. This is a critical finding for
clinicians working with children from all physical fitness
backgrounds, as despite a child’s body mass index, chil-
dren appear to reap some clinical benefit from physical
activity.
Although correlational studies also found a significant
relationship between increased levels of physical activity
and decreased levels of depression (as well as an enhanced
self-concept), other mental health outcomes were not
found to relate significantly to heightened levels of physical
activity. Yet, one critique of correlational studies in this
area is that they leave open the question as to whether
the relationship between physical activity and mental
health is simply an effect of negative affect on the child’s
motivation to engage in physical activity. The experimental
studies have somewhat clarified this relationship and will
likely provide a more accurate indicator of how much phys-
ical activity influences mental health outcomes in children.
Given that depression, anxiety, psychological distress,
emotional disturbance, and self-esteem were all positively
affected through randomized-controlled designs in both
children and adults across multiple studies, these findings
can be interpreted as robust (Larun et al., 2006;
Stathopoulou, Powers, Berry, & Smits, 2006).
As demonstrated in this analysis, the type of physical
activity children received had varying effects on their
mental health. RCT studies demonstrated the greatest
effect with circuit training/strength training activities and
mixed activity interventions, meaning a combination of
aerobic and resistance training exercise. The more children
engaged in these types of activities, the less adverse mental
health issues they experienced. Results from aerobic exer-
cise and resistance training can be found in numerous
studies based on adult populations, as both types of activ-
ity have resulted in consistently beneficial effects for par-
ticipants’ mental health. Possible mechanisms include an
increase in serotonin or other neurotransmitters associated
with the ‘‘endorphin’’ effect in alleviating negative affect,
although additional clinical studies are needed to specify
Meta-analysis of Physical Activity 9
by guest on January 12, 2011jpepsy.oxfordjournals.orgDownloaded from
the precise neurological pathways that mediate the rela-
tionship between physical activity and mood on a physio-
logical level (Stathopoulou et al., 2006).
Although there is a dearth of research in this area using
child participants, the level of intensity of the intervention
played a significant moderating effect in both RCT and
non-RCT studies. Interventions designed with high levels
of intensity had the greatest effect on children’s mental
health in RCT studies, while moderate-level activities ex-
erted a greater effect for non-RCT studies. Again, there is a
sparse research base in which to make sense of these find-
ings, but in the only meta-analysis to date studying this
relationship, Larun and colleagues found no difference
between low and high intensity exercise when assessing
effects on depression and anxiety (2006). However, multi-
ple studies on adult populations suggest an overwhelming
consensus in favor of high intensity exercise (Stathopoulou
et al., 2006). Perhaps with the addition of RCT studies in
the present analysis, this relationship was better discerned.
As argued for adult populations, higher intensity exercise
may enhance neurological, physiological and cognitive
factors that mediate the relationship between activity and
mood. Although more research is needed to confirm this
hypothesis, perhaps similar mechanisms are at work in
children (Shephard, 1996; Stathopoulou et al., 2006;
Wiles, Jones, Haase, Lawlor, Macfarlane, & Lewis, 2008).
Curiously, interventions done approximately 1 to
2 days per week and for more than 33 hr (spanning the
length of the intervention) were most effective in RCT stud-
ies. For non-RCT studies, interventions done approximate-
ly 1 day per week for no more than 20 hr were the most
effective. That is, interventions that were done more than
3 days per week or for more than a total of 20 hr did not
alleviate children’s mental health ailments for non-RCT
studies. Although this finding from RCT studies appears
to contradict findings with the non-RCT studies, the seem-
ingly low amount of hours could be explained by the
relatively short duration of physical activity interventions
used in the included studies. In other words, the average
length of time for physical activity interventions was
8.95 weeks (SD ¼4.5), ranging from 2 to 20 weeks for
non-RCT studies. For RCT-studies, the length of the inter-
vention phase was longer (M¼11.1 weeks, SD ¼3.6).
Thus, with a mean total of 20 hr for the non-RCT interven-
tions, this would equate to approximately 2.2 hr per week
of additional physical activity for children—around
44 min, 3 times per week. For a mean total of 33 hr
for non-RCT studies, the average amount of physical
activity would come to approximately 2.9 hr per week,
or 58 min, 3 times per week. The differential mean
intervention length across study designs likely affects the
total of hours needed for significant results. A number
of possibilities might explain this finding of children’s
need for fewer hours of total physical activity. First, it
could be that since children already receive relatively
short and sporadic bouts of physical activity throughout
the week (i.e., recess or game play; see Dencker, Bugge,
Hermansen & Andersen, 2010; Rowland, 1996) they may
not require as much physical activity for an intervention to
be effective in reducing negative mood. Another possibility
concerns the dearth of studies that included these descrip-
tors (frequency and duration of intervention) in their meth-
odology. For example, there was only one effect size from
which to code daily (5 days/week) physical activity for chil-
dren. Without knowing this information, it was impossible
to code for these features of dosage, and thus it is likely
that an accurate assessment of the dose-response relation-
ship could not be obtained, just as in the prior 2006
meta-analysis (Larun et al., 2006).
When designing physical activity interventions for
children, this study showed that individualized- or class-
wide interventions had the greatest effect on children’s
mental health. When the intervention was led by teachers,
researchers, or PE specialists, children showed the signifi-
cant reduction in mental health problems through physical
activity in both RCT and non-RCT studies. This finding
has practical applications, as children spend the majority
of their waking hours in school. With many children
unable to access mental health treatment through outpa-
tient or clinical settings, schools are the one place where
services are both mandated and free for children with di-
agnosed mental health ailments (Hoagwood & Johnson,
2003). Thus, schools have the potential to be a vehicle
for improving children’s mental health outcomes.
Gender was found to be a moderator in both RCT and
non-RCT studies, although the findings were inconsistent.
In RCT samples, males and mixed-gender groups showed
the largest gains from physical activity with respect to their
mental health outcomes. However, non-RCT studies
showed that girls benefit more than boys do when it
comes to the effects of physical activity on their mental
health. Correlational studies demonstrated yet another
finding and showed no differential effect by gender. The
methodological design of each study likely plays a critical
role in whether gender and age are found to be moderating
factors in the relationship between physical activity and
mental health. In other words, the differential findings be-
tween RCT, non-RCT, and correlational studies may help
elucidate why the ‘‘gender difference’’ finding has been
markedly inconsistent in this body of research (Wiles
et al., 2008). Some authors have postulated that physical
activity exerts a greater effect on females’ mental health
10 Ahn and Fedewa
by guest on January 12, 2011jpepsy.oxfordjournals.orgDownloaded from
outcomes due to their ‘‘feeling better’’ (i.e., higher
self-esteem and self-concept) about their appearance and
overall lack of physical activity compared to same-age male
peers (Lagerburg, 2005). Other authors argue that girls and
boys in fact are not affected differently, and that gender
differences between activity levels and psychological well-
being can be ‘‘smoothed out’’ over time (Parfitt & Eston,
2005). The present analysis, however, does show that
when RCT studies are analyzed separately, males appear
to reap larger psychological benefits from physical activity
than do their female peers. Further research is needed
to investigate the mechanisms behind these variations, per-
haps using a mixed-methods design to assess both female
and male children’s perceptions of the benefits of physical
activity (Loman, 2008).
Additional participant characteristics were found to
moderate the relationship between physical activity and
mental health outcome. For children who were diagnosed
as cognitively impaired or emotionally disturbed, effect
sizes from RCT studies were significantly greater compared
to children who were typically developing and did not have
an emotional disorder. In fact, the RCT studies used for
analysis demonstrated an effect size that was five times as
large for children with cognitive impairments and almost
twice as large for students with emotional disturbance.
Perhaps the severity of problems for these two groups of
children enhanced the effect of physical activity on their
mental health, just as children who were clinically diag-
nosed with a disorder or disability displayed higher levels
of mental health benefit than those children in the general
population without a clinical diagnosis. These findings are
critical for clinicians and school-based practitioners, as it
demonstrates the increased effectiveness of physical activ-
ity for children who display severe problem behaviors or
clinical symptomology.
As with any study, there are limitations that must be
addressed. First, regardless of both searching and including
unpublished and published studies, slight publication bias
existed for the current analysis, which might threaten the
validity of research findings in the current meta-analysis.
However, it should be pointed out that such problem re-
flects the way individual studies in the field are conducted
and disseminated (Sutton, 2009). In spite of the potential
validity threat due to publication bias, the current review at
least can inform the possible presence of publication bias
in the area and estimate the likely effect of bias based on
the distribution of the effect sizes from the available stud-
ies. By taking into account this potential validity threat, the
overall effect size between physical activity and children’s
mental health remained significant. Second, the majority of
studies (69%) did not include children’s ethnicity or
socioeconomic status. Thus, these variables could not be
included as potential moderators for the relationship be-
tween physical activity and child mental health outcomes.
Yet researchers have demonstrated higher levels of obesity
in racially, ethnically, and socioeconomically disadvan-
taged populations (Burton & VanHeest, 2007). It is likely
that different relationships exist for these populations than
for middle-class, Anglo-American groups. Future research
in this area should include detailed descriptors of the in-
cluded sample so that these relationships can be examined.
In summary, the present quantitative synthesis of
the literature demonstrated a small to moderate effect of
physical activity on children’s mental health. Given that
findings varied by methodological design, additional RCT-
designed studies are warranted to replicate and confirm
the current findings. The evidence from this meta-analysis
adds to the current body of knowledge documenting the
positive mental health effects of exercise in children, parti-
cularly for those children who exhibit a higher severity
of symptomology. For practitioners, physical activity
can thus be considered an effective component to already
well-established treatments (e.g., cognitive-behavioral ther-
apy) in the field. Clinicians, school-based professionals,
and parents should encourage physical activity in children,
not only for the physical health benefits, but for the
positive mental health outcomes as well.
Supplementary Data
Supplementary data can be found at: http://www.jpepsy.
oxfordjournals.org/.
Conflicts of interest: None declared.
References
Becker, B. J. (2000). Multivariate meta-analysis.
In H. E. A. Tinsley, & S. Brown (Eds.), Handbook of
applied and multivariate statistics and mathematical
modeling (pp. 499–525). San Diego: Academic Press.
Borenstein, M. (2009). Effect sizes for continuous data.
In H. M. Cooper, L. V. Hedges, & J. C. Valentine
(Eds.), The handbook of research synthesis and
meta-analysis. 2nd edn. New York, NY: Russell Sage
Foundation.
Burgeson, C. R., Weschler, H., Brener, N. D.,
Young, J. C., & Spain, C. G. (2001). Physical
education and activity: Results from the School
Health Policies and Programs Study 2000.
Journal of School and Health, 71(7), 279–293.
Meta-analysis of Physical Activity 11
by guest on January 12, 2011jpepsy.oxfordjournals.orgDownloaded from
Burton, L. J., & VanHeest, J. L. (2007). The importance
of physical activity in closing the achievement gap.
Quest, 59, 212–218.
Centers for Disease Control and Prevention (2008).
Healthy People 2010 update. Retrieved from http://
wonder.cdc.gov/data2010.
Conn, V. S. (2010). Depressive symptom outcomes of
physical activity interventions: Meta-analysis findings.
Annals of behavioral Medicine, 29, 128–138.
Dale, D., Corbin, C. B., & Dale, K. S. (2000). Restricting
opportunities to be active during school time: Do
children compensate by increasing physical activity
levels after school? Research Quarterly for Exercise and
Sport, 71(3), 240–248.
Dencker, M., Bugge, A., Hermansen, B., & Andersen, L. B.
(2010). Objectively measured daily physical
activity related to aerobic fitness in young children.
Journal of Sports Sciences, 28(2), 139–145.
Dixon, W. A., Mauzey, E. D., & Hall, C. R. (2003).
Physical activity and exercise: Implications for
counselors. Journal of Counseling & Development, 82,
502–505.
Ekeland, E., Heian, F., & Hagen, K. B. (2005). Can
exercise improve self-esteem in children and young
people? A systematic review of randomized controlled
trials. British Journal of Sports Medicine, 39, 792–798.
Farhat, T., Iannotti, R. J., & Simmons-Morton, B. G.
(2010). Overweight, obesity, youth, and health-risk
behaviors. American Journal of Preventive Medicine, 3,
258–267.
Fedewa, A. L., & Ahn, S. (in press). Determining the
effects of physical activity on children’s cognitive
outcome: A meta-analysis. Research Quarterly for
Exercise and Sport.
Gleser, L. J., & Olkin, I. (2009). Stochastically dependent
effect sizes. In H. M. Cooper, L. V. Hedges, &
J. C. Valentine (Eds.), The handbook of research
synthesis and meta-analysis. 2nd edn. New York, NY:
Russell Sage Foundation.
Hardman, K. (2008). Physical education in schools: A
global perspective. Kinesiology, 40(1), 5–28.
Hedges, L. V., & Olkin, I. (1985). Statistical methods for
meta-analysis. Orlando, FL: Academic Press.
Hoagwood, K., & Johnson, J. (2003). School psychology:
A public health framework I. From evidence-based
practices to evidence-based policies. Journal of School
Psychology, 41, 3–21.
Kremers, S. P. J., De Bruijin, G. J., Droomers, M.,
Van Lenthe, F., & Brug, J. (2007). Moderators of
environmental intervention effects on diet and
activity in youth. American Journal of Preventive
Medicine, 32(2), 163–172.
Lagerberg, D. (2005). Physical activity and mental health
in schoolchildren: A complicated relationship. Acta
Pediatrica, 94, 1699–1705.
Larun, L., Nordheim, L. V., Ekeland, E., Hagen, K. B., &
Heian, F. (2006). Exercise in prevention and
treatment of anxiety and depression among children
and young people. Cochrane Database of Systematic
Reviews, 3, 1–47.
Lipsey, M. W., & Wilson, D. B. (2001). Practical
meta-analysis. Thousand Oaks, California: Sage
Publications, Inc.
Loman, D. G. (2008). Promoting physical activity
in teen girls: Insight from focus groups.
The American Journal of Maternal-Child Nursing,
33(5), 294–299.
Morris, S. B. (2008). Estimating effect sizes from
pretest-posttest-control group designs. Organizational
Research Methods, 11(2), 364–386.
National Center for Health Statistics (2009). Health,
United States, 2008. Hyattsville, MD: U.S.
Department of Health and Human Services.
Ortega, F. B., Ruiz, J. R., Castillo, M. J., & Sjostrom, M.
(2008). Physical fitness in childhood and
adolescence: A powerful marker of health.
Pediatric Review, 32, 1–11.
Paluska, S. A., & Schwenk, T. L. (2000). Physical activity
and mental health. Journal of Sports Medicine, 29(3),
167–180.
Parfitt, G., & Eston, R. G. (2005). The relationship
between children’s habitual activity level and
psychological well-being. Acta Paediatrica, 94,
1790–1796.
Pate, R. R., Freedson, P. S., Sallis, J. F., Taylor, W. C.,
Sirard, J. C., Trost, S. G., & Dowda, M. (2002).
Compliance with physical activity guidelines:
Prevalence in a population of children and youth.
Annals of Epidemiology, 12, 303–308.
Pica, R. (1997). Beyond physical movement:
Why young children need to move. Children, 52(6),
4–11.
Raudenbush, S. W. (2009). Analyzing effect sizes:
Random-effects models. In B. S. Cooper, L.
V. Hedges, & J. C. Valentine (Eds.), The handbook of
research synthesis and meta-analysis. 2nd edn. New
York, NY: Russell Sage Foundation.
Rosenthal, R. (1994). Parametric measures of effect size.
In H. M. Cooper, & L. V. Hedges (Eds.), The
handbook of research synthesis. New York, NY:
Russell Sage Foundation.
12 Ahn and Fedewa
by guest on January 12, 2011jpepsy.oxfordjournals.orgDownloaded from
Rowland, T. W. (1996). Developmental exercise physiology.
Champaign, IL: Human Kinetics.
Simen-Kapeu, A., & Veugelers, P. J. (2010). Should
public health interventions aimed at reducing
childhood overweight and obesity be gender-focused?
BMC Public Health, 10, 1471–2458.
Stathopoulou, G., Powers, M. B., Berry, A. C.,
Smits, J. A., & Otto, M. W. (2006). Exercise interven-
tions for mental health: A quantitative and qualitative
review. Clinical Psychology and Practice, 13, 179–193.
Stevens, T. A., To, Y., Stevenson, S. J., &
Lochbaum, M. R. (2008). The importance of
physical activity and physical education in the
prediction of academic achievement. Journal of
Sport Behavior, 31, 368–388.
Stice, E., Shaw, H., & Marti, C.N. (2006). A
meta-analytic review of obesity prevention
programs for children and adolescents: The skinny
on interventions that work. Psychological Bulletin,
132(5), 667–691.
Sutton, A. J. (2009). Publication bias. In B. S. Cooper,
L. V. Hedges, & J. C. Valentine (Eds.), The Handbook
of Research Synthesis and Meta-analysis. New York,
NY: Russell Sage Foundation.
Thompson, R. (2005). The course and correlates
of mental health care received by young
children: Descriptive data from a longitudinal urban
high-risk sample. Children and Youth Services Review,
27, 39–50.
U.S. Public Health Service (2000). Report of the Surgeon
General’s Conference on Children’s Mental Health: A
national action agenda. Washington, DC: Department
of Health and Human Services.
Wang, F., & Veugelers, P. J. (2008). Self-esteem and
cognitive development in the era of the childhood
obesity epidemic. International Association for the
Study of Obesity, 9, 615–623.
Wiles, N. J., Jones, G. T., Haase, A. M., Lawlor, D. A.,
Macfarlane, G. J., & Lewis, G. (2008). Physical
activity and emotional problems amongst
adolescents. Society of Psychiatry and Epidemiology,
43, 765–772.
World Health Organization. (2009). Global strategy
on diet, physical activity and health. Retrieved
from http://www.who.int/dietphysicalactivity/
childhood/en/.
Meta-analysis of Physical Activity 13
by guest on January 12, 2011jpepsy.oxfordjournals.orgDownloaded from
