|
Physical Activity Guidelines Advisory Committee Report
Part G. Section 9: Youth
- Introduction
- Review of the Science
- Overview of Questions Addressed
- Data Sources and Process Used to Answer
the Questions
- Question 1: Is Physical Activity
Significantly Related to Cardiorespiratory Fitness Among Children and
Adolescents? If So, Is There an Established Dose-Response Pattern? Is the
Relation Influenced by Age, Developmental Status, Sex, Race/Ethnicity, or
Socioeconomic Status?
- Question 2: Is Physical Activity
Significantly Related to Muscular Strength Among Children and Adolescents? If
So, Is There an Established Dose-Response Pattern? Is the Relation Influenced
by Age, Developmental Status, Sex, Race/Ethnicity, or Socioeconomic Status?
- Question 3: Is Physical Activity
Significantly Related to Body Composition in Children and Adolescents? If So,
Is There an Established Dose-Response Pattern? Is the Relation Influenced by
Age, Developmental Status, Sex, Race/Ethnicity, or Socioeconomic Status?
- Question 4: Is Physical Activity
Significantly Related to Cardiovascular and Metabolic Health in Children and
Adolescents? If So, Is There an Established Dose-Response Pattern? Is the
Relation Influenced by Age, Developmental Status, Sex, Race/Ethnicity, or
Socioeconomic Status?
- Question 5: Is Physical Activity
Significantly Related to Bone Health in Children and Adolescents? If So, Is
There an Established Dose-Response Pattern? Is the Relation Influenced by Age,
Developmental Status, Sex, Race/Ethnicity, or Socioeconomic Status?
- Question 6: Is Physical Activity
Significantly Related to Mental Health in Children and Adolescents? If So, Is
There an Established Dose-Response Pattern? Is the Relation Influenced by Age,
Developmental Status, Sex, Race/Ethnicity, or Socioeconomic Status?
- Overall Summary and Conclusions
- Research Needs
- Reference List
Introduction
Physical activity in American children and adolescents has been a
concern of authorities in education, medicine and public health for more than
half a century. During most of this period, experts have focused on physical
fitness rather than physical activity, per se. During the post-World War II
era, concerns about military preparedness led to formation of the President's
Council on Physical Fitness and Sports. The Council initiated a youth physical
fitness testing program that was intended to promote participation in
fitness-enhancing physical activity in children and adolescents. In association
with that fitness testing program and others, standards for physical fitness in
young people have been developed.
Although these standards for physical fitness in youth have been
available for many years, only in the past decade have professional and
scientific organizations presented guidelines for physical activity in children
and youth. Different groups have taken various approaches to the task of
identifying recommended levels of physical activity for young persons. Some
expert panels have approached this task by focusing on the health effects of
controlled exercise training in youth. Other groups have considered
cross-sectional and longitudinal associations between physical activity and
various health-related factors.
The task of relating physical activity to indicators of health and
fitness is complex. Part of the complexity relates to 3 processes that are
ongoing during the first 2 decades of life: normal physical growth, biological
maturation, and behavioral development. These processes occur simultaneously
and interact, especially during adolescence, making their individual and
combined effects difficult to evaluate. Physical activity, a behavior that has
its own developmental pattern, is only one of many factors that may influence
indicators of health and fitness in youth. It may be difficult to partition
effects attributed to physical activity from those associated with normal
growth, maturation, and development.
Review of the Science
Overview of Questions Addressed
This chapter addresses key questions related to the relation between
physical activity and a select number of health-related outcomes in children
and adolescents. These outcomes are physical fitness, body composition,
cardiovascular and metabolic disease risk factors, bone health, and mental
health. For each of the selected health outcomes, the committee considered the
following questions:
- Is there a significant relation between physical activity and the
outcome?
- If so, has a dose-response pattern been established?
- If a relation is evident, is it influenced by age, developmental
status, sex, race/ethnicity, and/or socioeconomic status?
Data Sources and Process Used to Answer the
Questions
The Youth subcommittee decided to apply 3 important delimitations in
performing the review of scientific literature summarized here. First, the
review was limited to studies of school-aged children aged 5 to 19 years.
Although it certainly would be relevant to consider studies of younger
children, it was the subcommittee's judgment that the scientific literature on
physical activity and health is too limited in infants and preschool-age
children to support clear conclusions.
Second, the subcommittee opted to focus its review on the relation
between physical activity and the modest number of health-related outcomes
noted above. Third, the subcommittee focused on the effects of physical
activity on health outcomes as observed during childhood and
adolescence. The subcommittee recognized the significance of the
potential long-term effects of physical activity during childhood and
adolescence on health outcomes later in life. It also was concerned about the
potential influence of physical activity early in life with physical activity
in adulthood. However, the subcommittee judged that the scientific literature
pertinent to the latter 2 relationships is currently insufficient to inform
physical activity guidelines. Hence, the review presented in this chapter is
limited to an examination of the relation between physical activity and
selected health-related outcomes during childhood and adolescence.
For each of the aforementioned health-related outcomes, the subcommittee
performed a systematic evidence-based review of the literature using the
Physical Activity Guidelines for Americans Scientific Database as its
primary resource (see Part F. Scientific
Literature Search Methodology, for a detailed description of
the Database). The review consisted of publications from 1995 onward, with the
exception of some review papers on cardiorespiratory fitness. This was due to
the fact that many studies on the effects of endurance training on
cardiorespiratory fitness were published before 1995. The subcommittee examined
reviews, meta-analyses, randomized controlled trials (RCTs),
nonrandomized controlled trials, prospective cohort studies,
cross-sectional studies, and additional observational studies. As needed, the
subcommittee also used systematic reviews, meta-analyses, and original studies
from sources other than the Scientific Database.
Question 1: Is Physical Activity
Significantly Related to Cardiorespiratory Fitness Among Children and
Adolescents? If So, Is There an Established Dose-Response Pattern? Is the
Relation Influenced by Age, Developmental Status, Sex, Race/Ethnicity, or
Socioeconomic Status?
Conclusions on Relation and Dose-Response
Pattern
Physical activity is positively related to cardiorespiratory fitness in
children and youth, and both preadolescents and adolescents can achieve
improvements in cardiorespiratory fitness with exercise training. Endurance
training has been shown to increase VO2max by 5% to 15%. Due to
variability across studies, the optimal dose of physical activity needed to
attain improvements in cardiorespiratory fitness cannot be specified (1;2). In a recent review, Baquet and
colleagues (3) summarized the dose of exercise prescribed
across 22 controlled training studies. They concluded that an intensity greater
than 80% of maximal heart rate, a frequency of 3 to 4 days per week, a duration
of 30 to 60 minutes per session, and a length of 1 to 3 months resulted in
improvements in cardiorespiratory fitness (3).
Rationale for Relation and Dose-Response
Pattern
This review of the literature was based on an evaluation of 2 review
articles, 1 meta-analysis, 10 cross-sectional studies (Table G9.A1 summarizes these cross-sectional
studies), 1 prospective cohort study, and 21 experimental studies. The
experimental studies can be further classified as randomized trials (n=6),
group randomized trials (n=3), non-randomized trials (n=8), before and after
studies (n=2), and time series studies (n=2) (Table G9.A2 summarizes these experimental
studies). Typically, most cross-sectional studies either correlated
cardiorespiratory fitness with physical activity levels or compared active
youth to inactive youth. Cardiorespiratory fitness was assessed with a variety
of methods, including step test, cycle ergometer, 20-meter shuttle run, and
treadmill test. All of the studies reported an association between physical
activity and cardiorespiratory fitness. In particular, Ara and colleagues (4) reported that males who participated in 3 hours of
extracurricular physical activities per week in addition to regular physical
education classes had significantly greater aerobic fitness compared to males
who participated only in regular physical education classes. In another study,
Dollman and colleagues (5) measured both sedentary behavior
and moderate to vigorous physical activity. They reported that males who
watched television for more than 2 hours per day and engaged in more than 60
minutes of moderate to vigorous physical activity (MVPA) had higher
cardiorespiratory fitness compared to males who watched television for more
than 2 hours per day but obtained less than 60 minutes of MVPA (5). Females who engaged in more than 60 minutes of MVPA
(regardless of their television viewing habits) had greater cardiorespiratory
fitness levels than females who obtained less than 60 minutes of MVPA (5). In all of the remaining cross-sectional studies, the dose
of physical activity was not provided. Overall, cross-sectional studies
concluded that youth with higher physical activity levels tended to have higher
cardiorespiratory fitness levels.
In the only prospective cohort study that met the search criteria, Ara
and colleagues (6) assessed physical activity in 42 boys
with an average age of 9 years, and followed them for 3 years. The boys were
divided into a physical activity group (participating in at least 3 hours of
extracurricular physical activities per week plus regular physical education
classes) and a non-physical activity group (participating only in regular
physical education classes) (6). Cardiorespiratory fitness
was assessed with the 20-meter shuttle run test. At the conclusion of the
3-year period, the physical activity group maintained their cardiorespiratory
fitness levels, whereas the non-physical activity group decreased their
cardiorespiratory fitness levels (6).
Most of the 21 experimental studies reported increases in
cardiorespiratory fitness in a range from 5% to 15% with endurance training.
The most common activities were aerobics, running, cycling, using exercise
machines, stair climbing, basketball, and brisk walking. The dose of endurance
training varied across studies. Frequency ranged from 1 to 5 days per week,
duration was between 20 and 60 minutes per session, and intensity ranged from
70% to 90% of maximum heart rate (HRmax).
Conclusions on Developmental and
Demographic Influences
Both children and adolescents can increase their cardiorespiratory
fitness with endurance training, and males and females respond similarly to
endurance training. The literature is not adequate to support a conclusion
regarding race/ethnicity. Most studies did not report the socioeconomic status
of participants, thereby precluding conclusions about the influence of this
demographic factor.
Rationale for Developmental and Demographic
Influences
Age and/or Developmental Status
Children and adolescents can achieve improvements in cardiorespiratory
fitness with physical activity. Twenty-one experimental studies examining this
relation have included subjects who range in age from 5 to 18 years. In all but
one study (7), physical activity produced improvements in
cardiorespiratory fitness, whether preadolescents, adolescents, or both were
active.
Sex
Both males and females have demonstrated their capacity to attain
similar improvements, ranging from 5% to 15%, in cardiorespiratory fitness as a
result of endurance training (1;2;8-12).
Race/Ethnicity
Information about the potential influence of race/ethnicity on
cardiorespiratory fitness in youth is limited. Most studies have focused on
white children and adolescents, but of the 4 studies that examined the effect
of endurance training on cardiorespiratory fitness in African American youth,
all found significant improvements in cardiorespiratory fitness of 5% to 10%
(8;10;13;14). Crews and colleagues (15)
implemented a 12-week intervention among Hispanic children, and reported
significant improvements (16%) in cardiorespiratory fitness.
Socioeconomic Status
Most studies did not report the socioeconomic status of participants,
thereby preventing conclusions about the influence of this factor on physical
activity and cardiorespiratory fitness.
Question 2: Is Physical Activity
Significantly Related to Muscular Strength Among Children and Adolescents? If
So, Is There an Established Dose-Response Pattern? Is the Relation Influenced
by Age, Developmental Status, Sex, Race/Ethnicity, or Socioeconomic
Status?
Conclusions on Relation and Dose-Response
Pattern
Physical activity is positively related to muscular strength. In both
children and adolescents, resistance training 2 or 3 times per week
significantly improves muscular strength.
Rationale for Relation and Dose-Response
Pattern
A total of 5 review articles and 2 non-randomized trials were included
in this evaluation of the evidence. Malina (16) reviewed
22 experimental studies of pre- and early-pubertal youth and muscular strength
training programs and reported a significant increase in muscular strength.
Most of the resistance training programs were 8- or 12-week programs that
consisted of 2- and 3-day sessions separated by days of rest; the range of all
reviewed programs was 6 weeks to 21 months. Less than half of the studies
reported intensities, but of those that did, training intensities ranged from
50% to 85% of 1 repetition maximum (1RM), with 75% 1RM being the most common.
Conversely, when participants stopped the resistance training (detrained), they
experienced a decrease in muscular strength. Growth and maturation were taken
into account in this review, and Malina concluded that resistance training did
not have a negative effect on these developmental factors among pre- and
early-pubertal youth.
Blimkie and Bar-Or (17) reviewed 18 studies of
adolescents and concluded that moderate to high training loads resulted in
significant increases in muscular strength. However, Blimkie and Bar-Or also
noted that for both preadolescents and adolescents, "the optimal combination of
mode, intensity, volume and duration of training for strength
increases
has yet to be determined" (p.115). Other review articles
reported increases in muscular strength with resistance training among
prepubertal children (18-20).
Treuth and colleagues (21) implemented a
non-randomized resistance training study in a sample of obese girls aged 7 to
10 years. Over a period of 5 months, the girls trained with 6 upper body and 1
lower body exercises for 3 days per week, 20 minutes per session. The sequence
of exercises for each session was leg press, bench press, military press, bicep
curl, latissimus pull down, triceps extension, and sit-ups. Each participant
performed 2 sets of 12 repetitions for the upper body exercises and 2 sets of
15 repetitions for the leg press. Weight was gradually increased throughout the
program to 70% 1RM. At the conclusion of the trial, the intervention group
significantly increased their 1RM bench press by 19.6%, 1RM leg press by 20%,
and knee extensor strength by 35%.
Faigenbaum and colleagues (22) studied the effects
of a 9-week non-randomized progressive resistance training study in boys aged
13 years. The program consisted of resistance training exercises 2 days per
week for 90 minutes per session. A typical training session began with a
10-minute warm-up, followed by 2 or 3 types of Olympic-style lifts and then a
series of resistance exercises: barbell squat, leg curl, bench press, front
latissimus pull down, seated row, biceps curl, and triceps extension. For each
exercise, 3 sets were performed, with 1 to 4 repetitions for the Olympic-style
lifts per set, and with 12 to 15 repetitions decreasing to 8 to 10 repetitions
for the resistance exercises per set. The program increased leg strength by 19%
and upper body strength by 15%.
Conclusions on Developmental and
Demographic Influences
Both children and adolescents can increase their muscular strength with
resistance training, and males and females show similar relative increases in
strength with resistance training. The literature is too limited to support
conclusions about the influence of race/ethnicity and socioeconomic status.
Rationale for Developmental and Demographic
Influences
Age and/or Developmental Status
Children, pre- and early-adolescents can improve their muscular strength
with resistance training (16;18-20).
In addition, resistance training does not have adverse effects on growth and
maturation (16).
Sex
Both males and females can obtain increases in muscular strength with
resistance training (21;22), although
approximately half of the studies reviewed by Malina (16)
were of males only.
Race/Ethnicity
Information about the potential influence of race/ethnicity on muscular
strength is limited. Most studies have been conducted with white children and
adolescents.
Socioeconomic Status
Most studies did not report the socioeconomic status of participants,
thereby preventing conclusions about the influence of socioeconomic status on
muscular strength.
Question 3: Is Physical Activity
Significantly Related to Body Composition in Children and Adolescents? If So,
Is There an Established Dose-Response Pattern? Is the Relation Influenced by
Age, Developmental Status, Sex, Race/Ethnicity, or Socioeconomic Status?
Conclusions on Relation and Dose-Response
Pattern
Among normal-weight youth, those who have relatively high levels of
physical activity tend to have less adiposity than youth with low levels of
physical activity. However, programs that increase physical activity in
normal-weight youth typically have little effect on adiposity.
Controlled training studies with overweight/obese youth have observed
reductions in overall adiposity and visceral adiposity with exposure to regular
physical activity of moderate to vigorous intensity 3 to 5 times per week, for
30 to 60 minutes. The most consistent favorable effects of physical activity on
adiposity were found in studies that used dual-energy x-ray absorptiometry
(DXA) to estimate percent body fat and magnetic resonance imaging to estimate
visceral adipose tissue (VAT), in contrast to studies based on body mass index
(BMI) or skinfold estimates of percent body fat based on skinfold thicknesses.
Evidence for a dose-response pattern is inconsistent in the studies
reviewed.
Rationale for Relation and Dose-Response
Pattern
Caveats
Indicators of body composition change with chronological age (CA) and
associated changes in normal growth and maturation (18).
As a result, it is difficult to partition physical activity effects from those
expected with growth and maturation. On average, BMI declines during infancy
and early childhood, reaches a nadir at about 5 to 7 years, and then increases
through the remainder of childhood and adolescence. The timing of the increase
is labeled the "adiposity rebound." Fat-free mass (FFM) shows a growth pattern
similar to that of height, with a major adolescent spurt; fat mass (FM)
increases, on average, consistently with age. Percent fat (%F) increases during
childhood but declines during adolescence in males and continues to increase at
a slower pace in females during adolescence. Sex differences are negligible in
BMI; they are small in FFM and FM during childhood and increase during
adolescence (FFM males larger, FM females larger). The sex difference in %F
(greater in females than males) is consistent from childhood through
adolescence.
Indicators of body composition are also related to biological maturity
status. On average, among youth of the same CA, those advanced in maturity
status are larger in size, BMI, FFM, and FM compared to those "on time" or
delayed in maturity status. With the exception of pubertal status, only one of
the studies reviewed included age at peak height velocity (PHV) as a maturity
indicator, while no studies incorporated skeletal age. Many studies included an
estimate of pubertal status, either clinically assessed or self-reported stage
of breast or pubic hair in girls, or genital or pubic hair in boys; menarcheal
status is occasionally considered. Stages of breast and pubic hair and genital
and pubic hair are not equivalent in girls and boys, respectively. Pubertal
status so estimated simply means that the youth was in a particular stage; it
provides no information about when the youth entered the stage or how long he
or she had been in a stage. Further, pre-pubertal children (no overt signs of
puberty) of the same CA can vary up to 3 to 4 years in skeletal age.
As an indicator of adiposity, BMI has limitations when evaluating the
influence of physical activity in intervention studies. In normal-weight
children, BMI is about equally correlated with FFM and FM and %F; it is a
better indicator of overall body size (weight-for-height), not necessarily
adiposity. In overweight and obese youth, BMI may be more highly correlated
with %F, although some overweight or obese youth also have a large FFM.
Activity may alter body composition without a change in BMI. In addition, BMI
may have different meanings among ethnic groups, given well-established ethnic
variation in body proportions (especially relative leg length and, by
inference, relative upper limb length).
Measurement variability may be a factor in looking at changes in
skinfolds with intervention training studies. In the studies reviewed, the
change attributed to physical activity may be within the range of measurement
error. Also, the standard error of estimation (SEE) of %F prediction equations
from skinfolds is not considered; SEEs are in the range of 3-5%. A number of
more recent studies use DXA, which should improve the precision of body
composition estimates.
Evidence
This review of the evidence is based on an evaluation of 45
cross-sectional studies (Table G9.A3 summarizes
these cross-sectional studies), 21 prospective cohort studies, 21
experimental studies in normal-weight children and adolescents, and 16 training
studies in the overweight and/or obese. The 37 training studies can be further
classified as 13 randomized trials, 9 group randomized trials, 12
non-randomized trials, and 3 before-and-after studies. Study participants
ranged in age from 3 to 18 years, and a variety of indicators of physical
activity was used.
Cross-Sectional Studies
The majority of studies used correlation and regression, and samples
were of mixed weight status (normal-weight, overweight, obese). Across studies,
physical activity has a low and, at best, moderate relation with BMI, percent
body fat, fat mass, and skinfold thicknesses. The correlations are reasonably
consistent across studies considering the mix of methods used to measure and
estimate physical activity. The magnitude of correlations and regression
estimates indicates that physical activity accounts for a relatively small
percentage of the variance in BMI and indicators of adiposity, and that other
factors explain most of the variance. Nevertheless, youth who engage in more
physical activity, specifically vigorous physical activity, tend to have less
adiposity than those who engage in less physical activity (4;23-25).
Several analyses of cross-sectional data have suggested a number of
steps per day and energy expenditure or physical activity that are necessary
for maintaining normal weight in youth. Recommended cut-off points for normal
weight children are 12,000 and 15,000 steps per day for girls and boys aged 6
to 12 years, respectively (26), and 13,000 and 16,000
steps per day for girls and boys aged 5 to 12 years, respectively (27). An association between 60 minutes per day of physical
activity with an energy expenditure of 8 or more kcal/kg/day and acceptable
levels of BMI and percent body fat also has been noted in youth aged 911
years (28).
Prospective Cohort Studies
The prospective cohort studies are of mixed designs and are at times
difficult to interpret (Table G9.A4 summarizes
these prospective cohort studies). Several trends are apparent, however:
- The school-based CATCH intervention had no effect on BMI and
skinfolds (29;30).
- The Nurses' Health Study II offspring showed smaller than expected
estimated changes in BMI associated with physical activity, although the
association may be of clinical relevance if the effects are cumulative (31;32).
- One study suggested that active children may have a later adiposity
rebound than less active children, though it is not clear in the study whether
the rebound was modeled in individual children (33).
- One study considered changes relative to estimated age at peak
height velocity, with the results suggesting that an increase in physical
activity may control the accrual of fat mass from childhood through adolescence
in males (34).
- Other studies generally show a small relation between physical
activity levels and changes in indicators of adiposity or mixed results.
Experimental Studies in Children of Normal Weight or Mixed Weight
Status
With few exceptions, experimental studies show a small increase in BMI
and adiposity indicators, or no significant changes in the BMI and adiposity
indicators with training (Table G9.A5 summarizes
these experimental studies). Training protocols varied among studies, but
the majority focused on relatively continuous activity, primarily endurance
activities. Durations of protocols also varied less than 10 weeks (6
studies); 10 to 15 weeks (8 studies); 16 to 20 weeks (2 studies); longer than
20 weeks (7 studies) but results do not appear to vary with protocol
duration. Of the studies with durations longer than 20 weeks, results were
mixed. A 10month intervention of continuous activity (35) showed a significant reduction in percent body fat, but a
10-month intervention of brief high-impact physical activity (36) showed no effect on weight and fat mass. Results were
similar when the brief high-impact physical activity intervention was extended
over 2 years (37). Two interventions that extended over 1
school year had different results, with Schneider and colleagues (38) showing no effect of physical activity on percent body
fat and Viskic and colleagues (39) showing a larger
decrease in percent body fat in the experimental compared to the control group.
One study over 2 school years showed a smaller gain in BMI in an intervention
group that included parental support compared to a control group and an
intervention group without parental support (40). An even
longer study, which extended over 3 to 4 years, showed no influence of added
physical education on fat mass (41).
Two studies (35;42;43) were conducted in which investigators did not
specifically choose youth who were overweight or obese to participate. However,
the youth who chose to participate had mean baseline BMIs that met the
International Obesity Task Force criteria for overweight. The studies used a
relatively large dose of moderate to vigorous physical activity (80 minutes per
day, 5 days per week for 8 months (42) and 10 months (35)) and noted a small but significant reduction in percent
body fat. Youth with better attendance had a larger decline in percent body fat
(43) and a smaller increase in BMI (35) over the course of the study.
Experimental Studies in Overweight or Obese Children
Results among studies are somewhat variable, but most suggest a decline
in BMI and percent body fat in overweight or obese youth with training, though
there are several exceptions (Table G9.A6
summarizes these experimental studies). The most consistent results for
percent body fat and visceral adipose tissue are Gutin and colleagues (8;35;42-46). Most
studies use continuous, largely aerobic activity, 3 to 5 times per week for 30
to 60 minutes. Durations vary: 8 weeks (1 study); 10 weeks (1 study); 12 weeks
(4 studies); 3 to 5 months (4 studies); 6 to 10 months (4 studies). Two studies
of strength training show minimal effects on adiposity in obese youth (21;47).
Conclusions on Developmental and
Demographic Influences
Variations in the effects of physical activity on adiposity associated
with age, sex, biological maturity status, race/ethnicity, and socioeconomic
status have not been systematically considered in the literature. Studies are
variable in controlling for the potential influence of age per se and maturity
status in the respective analyses. No conclusions regarding the effects of age
and maturity can be made at this time.
Question 4: Is Physical Activity
Significantly Related to Cardiovascular and Metabolic Health in Children and
Adolescents? If So, Is There an Established Dose-Response Pattern? Is the
Relation Influenced by Age, Developmental Status, Sex, Race/Ethnicity, or
Socioeconomic Status?
Conclusions on Relation and Dose-Response
Pattern
Physical activity is positively related to cardiovascular and metabolic
health in youth. A dose-response relation appears to exist, in that greater
doses of physical activity are associated with higher levels of cardiovascular
and metabolic health. However, the precise pattern of the dose-response
relation has not yet been determined.
Rationale for Relation and Dose-Response
Pattern
To examine the relation between physical activity and cardiovascular and
metabolic health, a total of 43 studies were considered: 21 experimental
studies, 2 prospective cohort studies, and 20 cross-sectional studies. Of the
21 experimental studies, 13 were randomized trials, 2 were group randomized
trials, 2 were non-randomized trials, 2 were time series studies, 1 was a
before-and-after study, and 1 was another type of study that included a
comparison group.
Physical activity may exert much of its influence on cardiovascular and
metabolic health by enhancing fitness and reducing fatness, which in turn
influence the underlying processes leading to cardiovascular disease and type 2
diabetes. Thus, studies typically have focused on risk factors for these two
diseases, namely fasting levels of insulin, lipids, and inflammatory markers.
Some recent studies have gone further to determine whether physical activity
influences mechanisms, such as cardiac parasympathetic activity, and end-organ
parameters, such as endothelial function, left ventricular (LV) geometry and
function, arterial stiffness, and carotid intima-media thickness (IMT). Because
so little information is currently available on these variables, and because of
the interrelations among them and the cardiovascular disease/type 2 diabetes
risk factors, we have tried to draw generalizations across the entire risk
profile.
Observational studies have reported that youth who engage in relatively
large amounts of physical activity have more favorable risk profiles than youth
who engage in relatively little physical activity (48-56).
Because RCTs have shown that physical activity decreases total body and
visceral fatness (35;45;46), which are themselves related to poor risk status (57), it is noteworthy that, to some degree, the association
of physical activity to favorable risk profile is retained even after
controlling for the possible mediating effect of body fatness (58-62). Some evidence indicates that the relation of physical
activity to improved insulin sensitivity is clearer in boys than in girls (63). Evidence also suggests that the relation between level
of physical activity and lipids and lipoproteins is primarily with
triglycerides and HDL-cholesterol; physical activity has little influence on
LDL-cholesterol. However, in children with elevated LDL-cholesterol, increased
levels of physical activity may be associated with a prospective trend to lower
LDL-cholesterol (64).
In recent years, a metabolic syndrome underlying cardiovascular disease
and type 2 diabetes has been identified in adults, and the concept of risk
factor clustering as being especially detrimental has been extended to youth
(65). When investigators have derived clustering scores,
they have found that youth who engaged in more physical activity had better
scores than did inactive youth (53).
Investigations of physical activity and risk profiles have generally
focused on aerobic physical activity. However, some evidence is available that
youth with substantial muscle strength, as a proxy for strength-building
physical activity, have good insulin sensitivity (66).
This subject deserves further study.
Taken together, the observational results support the hypothesis that
physical activity is associated with a favorable risk profile. A number of
studies have tested this hypothesis using controlled interventions. Because of
the potential role of fatness as a mediator of the relation between physical
activity and risk profile, many RCTs have used subjects who were obese at
baseline.
The information available from such intervention trials in obese youth
suggests that controlled physical activity programs lasting 2 to 8 months have
favorable effects on many indices of cardiovascular and metabolic health,
including insulin sensitivity, lipid profile, indices of inflammation,
endothelial function, cardiac parasympathetic activity, and carotid IMT (10;44;67-72). It
appears that the favorable effects of physical activity on lipids are clearest
in youth who exhibit an especially elevated risk status at baseline (10;69). Some studies have shown that
physical activity interventions led to improvements in insulin sensitivity or
lipid profile that were to some degree independent of changes in body fatness
(73-75). However, obese youth who participated in a
school-based physical activity intervention and who improved in fitness,
fatness and fasting insulin concentration (76), lost their
gains over the subsequent summer when they were not engaged in regular physical
activity (77). This shows the importance of maintaining
exposure to physical activity on a long-term and continuous basis.
In contrast to results from physical activity intervention studies in
obese youth, studies of youth who varied over the spectrum of fatness at
baseline, have generally failed to provide evidence that physical activity
reduced fatness or improved risk profiles (7;78;79). This discrepancy between the
results of observational and intervention studies suggests that the dose of
physical activity needed in these subjects may be greater than that needed to
elicit such changes in obese youth. Research is needed on the impact of
physical activity interventions carried on for extended periods of time.
Because of the difficulty of conducting RCTs over the periods of time needed to
produce substantial changes in body fatness (i.e., years rather than months),
conclusive evidence from RCTs is quite difficult to obtain.
An important aspect of the physical activityhealth relationship is
the dose of physical activity that is associated with favorable risk status.
However, relatively little clear information is available on this matter. The
limited information available from observational studies suggests that at least
360 minutes per week of moderate-to-vigorous physical activity is associated
with a good risk profile (53). With respect to a desired
intensity of physical activity, some evidence indicates that vigorous physical
activity, such as that found in sports, may be more closely related to a
favorable risk status than is moderate physical activity (51;58). This is consistent with studies
showing that vigorous physical activity, more so than moderate physical
activity, is associated with lower amounts of fatness (80-83).
In the general population of youth, few experimental data exist to show
a beneficial effect of physical activity on fatness or risk status, perhaps
because the few investigations available used relatively small doses of
physical activity. It is likely that doses of controlled moderate-to-vigorous
physical activity greater than 300 minutes per week are needed for such youth
to prevent accretion of general and visceral fat (35).
Even when an intervention that employed a dose of this size had a favorable
effect on fatness, the changes in risk profile of the intervention and control
groups did not reach significance (42). It may be
necessary for youth to maintain the lower levels of fatness for years in order
to see clear effects on the fatness-associated risk profile.
Taken together, the observational and experimental evidence supports the
hypothesis that maintaining high amounts and intensities of physical activity
starting in childhood and continuing into the adult years will enable people to
maintain a favorable risk profile, less end-organ damage, and lower rates of
morbidity and mortality from cardiovascular disease and type 2 diabetes
mellitus. Taken collectively, the research suggests that moderate-to-vigorous
physical activity for at least 1 hour per day would help youth to maintain a
healthy cardiovascular disease and type 2 diabetes risk profile. Higher volumes
or intensities of physical activity probably have greater benefit.
Conclusions on Developmental and
Demographic Influences
Very little is known about the effects of age, developmental status,
sex, race/ethnicity, and socioeconomic status on the relation of physical
activity to cardiovascular disease and type 2 diabetes risk status.
Rationale for Developmental and Demographic
Influences
Very few studies have investigated interactions of physical activity
with age, developmental status, sex, race/ethnicity, or socioeconomic status.
Of those that have investigated such interactions, some have reported
contradictory findings. For example, a study of Danish children found that
physical activity was inversely related to insulin resistance in girls, but not
in boys (61) whereas a study of American youth found the
opposite result, namely that greater physical activity was associated with
better insulin sensitivity in boys, but not in girls (63).
Thus, interactions of physical activity with these factors are an important
topic for future investigations.
Question 5: Is Physical Activity
Significantly Related to Bone Health in Children and Adolescents? If So, Is
There an Established Dose-Response Pattern? Is the Relation Influenced by Age,
Developmental Status, Sex, Race/Ethnicity, or Socioeconomic Status?
Conclusions on Relation and Dose-Response
Pattern
Bone-loading physical activity increases bone mineral content and
density. Targeted weight-loading activities that simultaneously influence
muscular strength, done 3 or more days per week are effective. It is
challenging to compare mode and dose, as some studies observed or implemented
jumping activities, some used weight-bearing games, and some examined
resistance training activities. Intensities are reported as ground-reaction
force (GRF), levels from moderate to vigorous, or as a percent of the 1RM.
Rarely do doses vary within a study, supporting the need for dose-response
studies.
Rationale for Relation and Dose-Response
Pattern
The literature from 1995 to the present yielded 17 RCTs, 5 group
randomized trials (2 of which published follow up data 9 to 12 months after
study completion), and 7 prospective cohort studies that examined the relation
between physical activity and bone health. Specific outcome measures included
at least one of the following: bone mineral content (BMC), bone mineral density
(BMD), bone area (BA), stiffness index (SI), bone geometry and strength, and
periosteal circumference.
The osteogenic potential of physical activity is determined by the
magnitude of the external load, the dynamic nature of the load, the rate at
which the load is introduced, and the duration of the loading bout (84). Weight-bearing activities that introduce stress to the
skeleton through either GRF (e.g., running, jumping) or high-intensity
joint-reaction forces (e.g., weight lifting) have a greater effect on bone
mineral accretion than do weight-supported activities (e.g., bicycling,
swimming), and may be more effective in reducing future risk of osteoporosis
(85).
Studies that report a GRF show a minimum load or dose of 3X body weight
(BW) to be effective in changing BMC. Short duration bouts with GRF more than
5X BW have produced effects in the femur (86) and tibia
(87), compared to growth-related changes in controls
participating in usual weight-bearing activity during physical education
classes, with loads less than 5X BW.
Studies that focused on high-intensity jumping (at least 3X BW) for 3 to
12 minutes at a time, at least 3 days per week, showed an effect on femoral
neck or greater trochanter BMD (37;88-90). Adding high-intensity weight-bearing physical
activity (12 minutes, 3 times per week) to school-based physical education
classes resulted in positive gains in BMC of the spine and hip after 7 months
in early pubertal girls and pre-pubertal boys and then at 20 months in
pre-pubertal boys and pubertal girls (36;37;88;91). Boys
also demonstrated changes in bone structural geometry (bone strength) after 20
months.
In most studies, an exercise or physical activity regimen of at least 2
days per week (35) and up to 5 days per week (87;92) resulted in positive effects on
bone health. Most studies implemented the intervention 3 days per week (36;37;88;90;91). The majority of studies have been conducted over a 6 to
20 month period. A duration of only 6 months was too short to demonstrate
significant changes in some of the studies (93) and yet
one study showed a positive effect after just 4 months of high-intensity
jumping rope (GRF=3.2 X BW) in girls aged 14 to 15 years (94).
Conclusions on Developmental and
Demographic Influences
The relation between physical activity and bone health is influenced by
age and developmental status. A number of studies suggest that the window of
opportunity for the effects of physical activity on bone mineralization in both
boys and girls is during early puberty and pre-menarchal years. During the
period of peak BMC velocity (12.7 years for girls; 14.1 years for boys), a
greater increase in BMC is seen for highly active than less active children.
The bone health of both boys and girls is improved by physical activity.
Limited information is available about the influence of race/ethnicity because
most studies examined only white children and many studies did not report race
at all. Most of the published studies do not routinely present data on
socioeconomic status, so it is difficult to determine whether differences exist
on this demographic parameter.
Rationale for Developmental and Demographic
Influences
Age and/or Developmental Status
The effect of mechanical loading on the skeleton is dependent on both
age and maturity (i.e., hormone levels) (95), particularly
around the peak BMC velocity. A number of recent studies showing positive
effects from physical activity suggest that the window of opportunity for bone
mineralization effects resulting from the activity, in both boys and girls, is
during early puberty and pre-menarchal years (36;90;91;96-99).
Recently, MacDonald and colleagues showed an effect on distal tibia strength in
pre-pubertal boys, not girls, using peripheral quantitative computed tomography
(pQTC), after a 16-month intervention period (87). These
studies have shown effects for trabecular bone in particular, although some
have demonstrated an effect on cortical bone (87;99). Some studies in menarchal or post menarchal girls have
not shown greater improvements in bone mineral content compared to controls (93;100;101),
though others have shown improvement (37;94;102;103). It
is difficult to put an age to the prepubescent period because increases in
obesity boost adiposity, which may influence the biologic age at which it
occurs and hence the window of opportunity. However, most of the prepubertal
studies have examined 812 year olds and the pubertal/post pubertal
studies have examined 12-15 year olds. Only one study examined preschoolers
ages 3 to 5 years (92), and found an increase in
periosteal circumference after 12 months of gross motor physical activity.
Physically inactive children may fail to realize their potential for
peak bone mass during the growing years, particularly the pre-pubescent and
pubertal period. Given the inadequate levels of physical activity among
American youth of all ages, the long-term consequences on bone health may
present a serious disease burden in future decades. Therefore, from a public
health perspective it is difficult to confine the advice to youth who are
verging on or at puberty.
Sex
The bone health of both boys and girls benefits from physical activity.
The majority of studies focused on girls, but 4 randomized studies have shown
effects in boys, all of whom were pre-pubertal at baseline (87;88;91;96).
Race/Ethnicity
Most of the studies have been performed with white children and some
with Asian children (36;37;88;91), although many studies do not
report race/ethnicity at all. Barbeau recently reported the gains in total body
BMD in black girls ages 8 to 12 years after a 10-month physical activity
program (35). This study showed a positive relation
between gains in fitness and increases in total body BMD and BMC.
Socioeconomic Status
Most of the published RCT and group RCT studies did not present data on
socioeconomic status so it is difficult to determine whether such differences
exist.
Question 6: Is Physical Activity
Significantly Related to Mental Health in Children and Adolescents? If So, Is
There an Established Dose-Response Pattern? Is the Relation Influenced by Age,
Developmental Status, Sex, Race/Ethnicity, or Socioeconomic Status?
Conclusions on Relation and Dose-Response
Pattern
Physical activity during childhood and adolescence exerts a beneficial
effect on several mental health outcomes. These include symptoms of anxiety and
depression, self-esteem, and physical self-concept. The varying methodologies
and insufficient numbers of intervention trials preclude inferences about
dose-response patterns.
Rationale for Relation and Dose-Response
Pattern
Although the burden of poor mental health is understudied in youth, the
prevalence of psychiatric disorders and symptomatology is known to be
substantial. The lifetime prevalence of major depression among youth has been
estimated to be between 15% and 20% (104). Twice as many
female as male youth have reported symptoms of major depression (105). An even broader spectrum of mental well-being is
particularly relevant to youth populations, including self-esteem and academic
performance.
A burgeoning body of evidence documents the effects of physical activity
on neurological and psychological processes in adults, and the number of
studies in children and adolescents also is growing. The evidence for the
former has been described in detail elsewhere in this report in Part G. Section 8: Mental Health.
The quality of the evidence base for youth, especially the relatively few RCTs
and longitudinal population-based cohort studies, constrain the aspects of
mental health that may be examined in this brief synthesis. Although a limited
number of studies have examined the association between physical activity and
mental health among youth, they indicate an inverse association between
physical activity and depressive symptoms (15;106-114) and anxiety (15;107;110;111;114). Studies also indicate a positive association between
physical activity and self-esteem and self-concept (14;107;111;115-119). In addition, some research studies indicate an
association between physical activity and academic performance (42;108;120-122).
Twelve primary research articles were reviewed: 1 randomized controlled trial,
2 group RCTs, 2 prospective cohort studies, 3 non-randomized trials, and 4
cross-sectional studies. The outcomes targeted in these studies were depressive
symptoms, anxiety, academic performance, and self-esteem/ self-concept.
Depressive Symptoms
Of the 6 identified studies that measured depressive symptoms, 2 were
intervention trials (one randomized and one non-randomized), 1 was a
prospective cohort study, and 3 were cross-sectional studies.
The randomized trial was a 12-week intervention implemented in 66
Hispanic fourth graders (15). The aerobic group
participated in physical activities and maintained a mean heart rate of 134
beats per minute for 20 minutes, 3 days per week (15). The
authors concluded that the moderate to vigorous physical activity obtained
during the intervention reduced depressive symptoms (15).
Annesi and colleagues (109) implemented a 12-week
non-randomized intervention among 90 children aged 9 to 12 years, and found a
significant decrease in depression and a significant improvement in mood. Too
few intervention trials were found to permit assessment of dose-response or
separate influences of different activity types.
Motl and colleagues (106) followed 7th graders
prospectively for 2 years and assessed nonschool related physical
activity and depressive symptoms. They determined that changes in physical
activity were inversely related to changes in depressive symptoms over the
2-year period (106). Recent longitudinal cohort studies
also have suggested associations between lower levels of emotional symptoms and
peer problems among boys who were physically active 3 years earlier (117).
All of the 3 cross-sectional studies found an inverse relation between
physical activity and depressive symptoms. Parfitt and Eston (107) measured physical activity objectively with pedometers,
and depression with the Childhood Depression Inventory among 70 children aged
10 years, and they reported an inverse correlation between physical activity
and depressive symptoms (r = 0.60) (107). The 2
other cross-sectional studies measured sports participation and depressive
symptoms of 89 youth in 12th grade (108) and 1,038 high
school students (110). Field and colleagues (108) reported that youth who were more physically active had
significantly less depressive symptoms than their less-active peers, and Pastor
and colleagues (110) reported a negative correlation
between sports participation and depressive symptoms (r = 0.14). A recent
expert panel review also found cross-sectional data that demonstrated weak
inverse associations between physical activity and scores on measures of
depressive symptoms (123).
Further, the same expert panel review found quasi-experimental studies
that showed strong positive effects of physical activity in decreasing anxiety
scores (123). Too few intervention trials were found to
permit assessment of dose-response or separate influences of different activity
types, however. Several recent cross-sectional studies have linked higher
levels of physical activity to higher mental health scores and fewer feelings
of sadness and suicidal ideation in ethnically and/or socioeconomically diverse
samples, although evidence is insufficient to draw conclusions about
differential sociodemographic effects (124;125).
Anxiety
Of the 3 identified studies that measured anxiety, 1 was a randomized
trial, and 2 were cross-sectional studies. One of the cross-sectional studies,
which focused on children aged 10 years (107), found an
inverse association between objectively measured physical activity and anxiety
(r = 0.48). In the other, which examined a large sample of high school
students (n=1,038), Pastor and colleagues (110) reported
a small, but significant inverse relation between sports participation and
anxiety (r = 0.07). Conversely, a randomized trial of 66 Hispanic
children in 4th grade did not produce changes in anxiety symptoms (15). The recent expert panel review mentioned previously
found cross-sectional data to have demonstrated weak inverse associations
between physical activity and scores on measures of anxiety symptoms (123).
Academic Performance
Four studies assessed the relation between physical activity and
academic performance: 2 group RCTs, 1 prospective cohort study, and 1
cross-sectional study. Sallis and colleagues (120)
administered the SPARK physical education program among 754 children in 4th to
6th grade, using 2 levels of implementation (Physical Education Specialists and
Trained Teachers) compared to a control group (standard physical education).
The SPARK program consisted of 30-minute sessions at least 3 times per week.
Academic performance was measured with the Metropolitan Achievement Tests (120). The authors concluded that the SPARK program had a
favorable effect on academic achievement. The students in the Specialist
condition had significantly higher reading scores compared to the control
group, and the students in the Trained Teacher condition had significantly
higher language, reading, and basic battery scores compared to the control
group (120). In addition, the SPARK program had no
detrimental effects on academic performance even though it involved a
significant investment of time (2 times the amount of instruction per week
compared to the control group) (120).
Yin and colleagues (42) implemented the Georgia
FitKid Project among 525 children in 3rd grade. The program consisted of
80-minute physical activity sessions 3 days per week, and academic performance
was assessed with criterion-referenced competency tests. The authors reported
no differences in academic scores between the intervention group (with 40%+
attendance) and the control group (42).
The 2 remaining studies found a positive relation between physical
activity and academic performance. A total of 214 children in 6th grade were
observed prospectively, and youth who met the Healthy People 2010 vigorous
physical activity standards had higher academic scores compared to their peers
who did not meet the standards (121). Field and
colleagues (108) reported a cross-sectional positive
association between physical activity and grade point average.
These findings are consistent with recent reviews of the literature.
Although observational studies have consistently found relationships between
physical fitness and grades and test scores, those between physical activity
and direct measures of academic achievement often have had null findings (126;127). Similarly, intervention
studies have been few in number, often had design weaknesses, and infrequently
demonstrated improvements in academic achievement (126;127). They have, however, generally found no decrements in
academic outcomes, despite substitution of activity time for didactic
instruction (126). Salutary effects on indirect measures
of academic performance, such as on-task behavior, disruptiveness, memory,
concentration, and homework completion, have more consistently been linked to
physical activity (123;126;128).
Self-Esteem and Self-Concept
DeBate and colleagues (115) assessed the impact of
the Girls on the Run program on self-esteem of 322 girls aged 8 to 12 years.
The program consisted of 60-minute sessions 2 days per week, and self-esteem
was measured with the Rosenberg self-esteem scale (115).
The authors concluded that self-esteem increased significantly (115). In a cross-sectional study of 70 children aged 10
years, physical activity (assessed by pedometry) was positively associated with
global self-esteem (r = 0.66) (107). Annesi and
colleagues (14) implemented a non-randomized trial among
570 African American children that consisted of physical activity sessions for
45 minutes, 3 days per week for 12 weeks. They determined that exercise
self-efficacy increased among girls aged 9 to 12 years, but no changes were
detected in boys or younger girls (14). Lastly, Dishman
and colleagues (116) reported a positive association
between physical self-concept and physical activity among 1,250 girls in 12th
grade.
Conclusions on Developmental and
Demographic Influences
It is difficult to draw conclusions about age and sex because most
relevant studies have included children or adolescents within a narrow range of
ages and a single sex, precluding sub-group analyses by age or sex. Favorable
influences have been reported across age groups, but within-study comparisons
have not generally been reported. Similarly, most studies do not analyze data
by race/ethnicity or socioeconomic status; therefore, it is difficult to make
conclusions about their influence on the relation between physical activity and
mental health.
Overall Summary and Conclusions
The subcommittee's review of the scientific literature supports the
overall conclusion that physical activity provides important health benefits
for children and adolescents. This conclusion is based on findings of
observational studies in which higher levels of physical activity were found to
be associated with more favorable health parameters as well as experimental
studies in which exercise treatments caused improvements in health-related
factors. The documented health benefits include increased physical fitness
(both cardiorespiratory fitness and muscular strength), reduced body fatness,
favorable cardiovascular and metabolic disease risk profiles, enhanced bone
health, and reduced symptoms of depression and anxiety.
The types and amounts of physical activity required to produce health
benefits vary across the health outcomes. Also, because of limitations in the
scientific evidence base, it is not possible to draw definitive conclusions
regarding the minimal or optimal doses of physical activity needed to provide
health benefits in young persons. Nonetheless, considering all the evidence,
the subcommittee concluded that important health benefits can be expected to
accrue to most children and youth who participate daily in 60 or more minutes
of moderate to vigorous physical activity. Further, the subcommittee concluded
that certain specific types of physical activity must be included in an overall
physical activity pattern in order for children and youth to gain comprehensive
health benefits. These include regular participation in each of the following
types of physical activity on 3 or more days per week: resistance exercise to
enhance muscular strength in the large muscle groups of the trunk and limbs,
vigorous aerobic exercise to improve cardiorespiratory fitness and
cardiovascular and metabolic disease risk factors, and weight-loading
activities to promote bone health. It is the subcommittee's judgment that these
specific types of physical activity can be appropriately performed to create a
60 minute or more per day activity pattern.
The subcommittee was not charged with considering the scientific
literature on behavioral and programmatic interventions to provide and promote
physical activity in children and youth. Nonetheless, the subcommittee feels
strongly that young persons should obtain their health-promoting physical
activity in ways that will allow them to attain health benefits over the short
term as well as encourage them to maintain a physically active lifestyle over
the long term. Experiences that are consistent with these goals involve
participation in physical activities that are developmentally appropriate, that
minimize the potential risks of overtraining and injuries, and that provide
participants with opportunities for enjoyable participation in a wide range of
specific forms of physical activity.
Research Needs
In reviewing the scientific literature, it became apparent that many
research needs exist regarding the health benefits of physical activity among
youth. Specifically, the subcommittee recommends that research be conducted to:
- Determine the types and amounts of physical activity that are needed
to prevent the development of excessive adiposity during childhood and
adolescence;
- Establish the dose-response pattern for the relation between
physical activity and bone health in children and adolescents;
- Identify the optimal types and amounts of physical activity to
maintain cardiovascular and metabolic health during childhood and adolescence;
- Determine whether physical activity affects classroom behavior and
academic achievement in children and adolescents; and
- Determine the extent to which age, developmental status, sex,
race/ethnicity, and socioeconomic status influence the effects of physical
activity on body composition, cardiovascular and metabolic health, bone health,
and mental health.
Reference List
- Shephard RJ. Effectiveness of training programmes
for prepubescent children. Sports Med. 1992 Mar;13(3):194-213.
- Payne VG, Morrow JR, Jr. Exercise and VO2 max in
children: a meta-analysis. Res.Q.Exerc.Sport 1993 Sep;64(3):305-13.
- Baquet G, van PE, Berthoin S. Endurance training
and aerobic fitness in young people. Sports Med. 2003;33(15):1127-43.
- Ara I, Vicente-Rodriguez G, Jimenez-Ramirez J,
Dorado C, Serrano-Sanchez JA, Calbet JA. Regular participation in sports is
associated with enhanced physical fitness and lower fat mass in prepubertal
boys. Int.J.Obes.Relat Metab Disord. 2004 Dec;28(12):1585-93.
- Dollman J, Ridley K. Differences in body fatness,
fat patterning and cardio-respiratory fitness between groups of Australian
children formed on the basis of physical activity and television viewing
guidelines. J.Phys.Act.Health 2006;3(2):191-9.
- Ara I, Vicente-Rodriguez G, Perez-Gomez J,
Jimenez-Ramirez J, Serrano-Sanchez JA, Dorado C, Calbet JA. Influence of
extracurricular sport activities on body composition and physical fitness in
boys: a 3-year longitudinal study. Int.J.Obes.(Lond) 2006
Jul;30(7):1062-71.
- Stoedefalke K, Armstrong N, Kirby BJ, Welsman JR.
Effect of training on peak oxygen uptake and blood lipids in 13 to 14-year-old
girls. Acta Paediatr. 2000 Nov;89(11):1290-4.
- Gutin B, Cucuzzo N, Islam S, Smith C, Stachura
ME. Physical training, lifestyle education, and coronary risk factors in obese
girls. Med.Sci.Sports Exerc. 1996 Jan;28(1):19-23.
- McManus AM, Armstrong N, Williams CA. Effect of
training on the aerobic power and anaerobic performance of prepubertal girls.
Acta Paediatr. 1997 May;86(5):456-9.
- Ewart CK, Young DR, Hagberg JM. Effects of
school-based aerobic exercise on blood pressure in adolescent girls at risk for
hypertension. Am.J.Public Health 1998 Jun;88(6):949-51.
- Williford HN, Blessing DL, Scharff-Olson M,
Brown J. Injury rates and physiological changes associated with lateral motion
training in females. Int.J.Sports Med. 1996 Aug;17(6):452-7.
- Adiputra N, Alex P, Sutjana DP, Tirtayasa K,
Manuaba A. Balinese dance exercises improve the maximum aerobic capacity.
J.Hum.Ergol.(Tokyo) 1996 Jun;25(1):25-9.
- Williford HN, Blessing DL, Duey WJ, Barksdale
JM, Wang N, Olson MS, Teel S. Exercise training in black adolescents: changes
in blood lipids and Vo2max. Ethn.Dis. 1996;6(3-4):279-85.
- Annesi JJ, Westcott WL, Faigenbaum AD, Unruh JL.
Effects of a 12-week physical activity protocol delivered by YMCA after-school
counselors (Youth Fit for Life) on fitness and self-efficacy changes in
5-12-year-old boys and girls. Res.Q.Exerc.Sport 2005 Dec;76(4):468-76.
- Crews DJ, Lochbaum MR, Landers DM. Aerobic
physical activity effects on psychological well-being in low-income Hispanic
children. Percept.Mot.Skills 2004 Feb;98(1):319-24.
- Malina RM. Weight training in youth-growth,
maturation, and safety: an evidence-based review. Clin.J.Sport Med. 2006
Nov;16(6):478-87.
- Blimkie CJR, Bar-Or O. Trainability of muscle
strength, power and endurance during childhood. In: Bar-Or O, editor. The Child
and Adolescent Athlete. Oxford: Blackwell Science; 1996. p. 113-29.
- Malina RM, Bouchard C, Bar-Or O. Growth,
maturation, and physical activity. Champaign, Ill: Human Kinetics; 2004.
- Mahon AD. Exercise training. In: Armstrong N,
van Mechelen W, editors. Paediatric Exercise Science and Medicine. Oxford:
Oxford University Press; 2000. p. 201-22.
- Bar-Or O, Rowland TW. Pediatric exercise
medicine : from physiologic principles to health care application. Champaign,
IL: Human Kinetics; 2004. p. 46-59.
- Treuth MS, Hunter GR, Pichon C, Figueroa-Colon
R, Goran MI. Fitness and energy expenditure after strength training in obese
prepubertal girls. Med.Sci.Sports Exerc. 1998 Jul;30(7):1130-6.
- Faigenbaum AD, McFarland JE, Johnson L, Kang J,
Bloom J, Ratamess NA, Hoffman JR. Preliminary evaluation of an after-school
resistance training program for improving physical fitness in middle school-age
boys. Percept.Mot.Skills 2007 Apr;104(2):407-15.
- Forshee RA, Anderson PA, Storey ML. The role of
beverage consumption, physical activity, sedentary behavior, and demographics
on body mass index of adolescents. Int.J.Food Sci.Nutr. 2004
Sep;55(6):463-78.
- Kawabe H, Murata K, Shibata H, Hirose H,
Tsujioka M, Saito I, Saruta T. Participation in school sports clubs and related
effects on cardiovascular risk factors in young males. Hypertens.Res. 2000
May;23(3):227-32.
- Schmidt GJ, Stensel DJ, Walkuski JJ. Blood
pressure, lipids, lipoproteins, body fat and physical activity of Singapore
children. J.Paediatr.Child Health 1997 Dec;33(6):484-90.
- Tudor-Locke C, Pangrazi RP, Corbin CB,
Rutherford WJ, Vincent SD, Raustorp A, Tomson LM, Cuddihy TF. BMI-referenced
standards for recommended pedometer-determined steps/day in children. Prev.Med.
2004 Jun;38(6):857-64.
- Duncan JS, Schofield G, Duncan EK. Step count
recommendations for children based on body fat. Prev.Med. 2007
Jan;44(1):42-4.
- Wittmeier KD, Mollard RC, Kriellaars DJ.
Objective assessment of childhood adherence to Canadian physical activity
guidelines in relation to body composition. Appl.Physiol Nutr.Metab 2007
Apr;32(2):217-24.
- Luepker RV, Perry CL, McKinlay SM, Nader PR,
Parcel GS, Stone EJ, Webber LS, Elder JP, Feldman HA, Johnson CC, et al.
Outcomes of a field trial to improve children's dietary patterns and physical
activity. The Child and Adolescent Trial for Cardiovascular Health. CATCH
collaborative group. JAMA 1996 Mar 13;275(10):768-76.
- Nader PR, Stone EJ, Lytle LA, Perry CL, Osganian
SK, Kelder S, Webber LS, Elder JP, Montgomery D, Feldman HA, et al. Three-year
maintenance of improved diet and physical activity: the CATCH cohort. Child and
Adolescent Trial for Cardiovascular Health. Arch.Pediatr.Adolesc.Med. 1999
Jul;153(7):695-704.
- Berkey CS, Rockett HR, Field AE, Gillman MW,
Frazier AL, Camargo CA, Jr., Colditz GA. Activity, dietary intake, and weight
changes in a longitudinal study of preadolescent and adolescent boys and girls.
Pediatrics 2000 Apr;105(4):E56.
- Berkey CS, Rockett HR, Gillman MW, Colditz GA.
One-year changes in activity and in inactivity among 10- to 15-year-old boys
and girls: relationship to change in body mass index. Pediatrics 2003 Apr;111(4
Pt 1):836-43.
- Moore LL, Gao D, Bradlee ML, Cupples LA,
Sundarajan-Ramamurti A, Proctor MH, Hood MY, Singer MR, Ellison RC. Does early
physical activity predict body fat change throughout childhood? Prev.Med. 2003
Jul;37(1):10-7.
- Mundt CA, Baxter-Jones AD, Whiting SJ, Bailey
DA, Faulkner RA, Mirwald RL. Relationships of activity and sugar drink intake
on fat mass development in youths. Med.Sci.Sports Exerc. 2006
Jul;38(7):1245-54.
- Barbeau P, Johnson MH, Howe CA, Allison J, Davis
CL, Gutin B, Lemmon CR. Ten months of exercise improves general and visceral
adiposity, bone, and fitness in black girls. Obesity.(Silver.Spring) 2007
Aug;15(8):2077-85.
- MacKelvie K, McKay HA, Khan KM, Crocker PR. A
school-based exercise intervention augments bone mineral accrual in early
pubertal girls. J.Pediatr. 2001 Oct;139(4):501-8.
- MacKelvie KJ, Khan KM, Petit MA, Janssen PA,
McKay HA. A school-based exercise intervention elicits substantial bone health
benefits: a 2-year randomized controlled trial in girls. Pediatrics 2003
Dec;112(6 Pt 1):e447.
- Schneider M, Dunton GF, Bassin S, Graham DJ,
Eliakim AF, Cooper DM. Impact of a school-based physical activity intervention
on fitness and bone in adolescent females. J.Phys.Act.Health 2007
Jan;4(1):17-29.
- Viskic-Stalec N, Stalec J, Katic R, Podvorac D,
Katovic D. The impact of dance-aerobics training on the morpho-motor status in
female high-schoolers. Coll.Antropol. 2007 Mar;31(1):259-66.
- Haerens L, Deforche B, Maes L, Stevens V, Cardon
G, De B, I. Body mass effects of a physical activity and healthy food
intervention in middle schools. Obesity.(Silver.Spring) 2006
May;14(5):847-54.
- Sundberg M, Gardsell P, Johnell O, Karlsson MK,
Ornstein E, Sandstedt B, Sernbo I. Peripubertal moderate exercise increases
bone mass in boys but not in girls: a population-based intervention study.
Osteoporos.Int. 2001;12(3):230-8.
- Yin Z, Gutin B, Johnson MH, Hanes J, Jr., Moore
JB, Cavnar M, Thornburg J, Moore D, Barbeau P. An environmental approach to
obesity prevention in children: Medical College of Georgia FitKid Project year
1 results. Obes.Res. 2005 Dec;13(12):2153-61.
- Yin Z, Moore JB, Johnson MH, Barbeau P, Cavnar
M, Thornburg J, Gutin B. The Medical College of Georgia Fitkid project: the
relations between program attendance and changes in outcomes in year 1.
Int.J.Obes.(Lond) 2005 Sep;29 Suppl 2:S40-S45.
- Gutin B, Owens S, Slavens G, Riggs S, Treiber F.
Effect of physical training on heart-period variability in obese children.
J.Pediatr. 1997 Jun;130(6):938-43.
- Gutin B, Barbeau P, Owens S, Lemmon CR, Bauman
M, Allison J, Kang HS, Litaker MS. Effects of exercise intensity on
cardiovascular fitness, total body composition, and visceral adiposity of obese
adolescents. Am.J.Clin.Nutr. 2002 May;75(5):818-26.
- Owens S, Gutin B, Allison J, Riggs S, Ferguson
M, Litaker M, Thompson W. Effect of physical training on total and visceral fat
in obese children. Med.Sci.Sports Exerc. 1999 Jan;31(1):143-8.
- Treuth MS, Hunter GR, Figueroa-Colon R, Goran
MI. Effects of strength training on intra-abdominal adipose tissue in obese
prepubertal girls. Med.Sci.Sports Exerc. 1998 Dec;30(12):1738-43.
- Raitakari OT, Taimela S, Porkka KV, Telama R,
Valimaki I, Akerblom HK, Viikari JS. Associations between physical activity and
risk factors for coronary heart disease: the Cardiovascular Risk in Young Finns
Study. Med.Sci.Sports Exerc. 1997 Aug;29(8):1055-61.
- Matsui I, Nambu S, Baba S. Evaluation of fasting
serum insulin levels among Japanese school-age children.
J.Nutr.Sci.Vitaminol.(Tokyo) 1998 Dec;44(6):819-28.
- Eisenmann JC, Katzmarzyk PT, Perusse L, Bouchard
C, Malina RM. Estimated daily energy expenditure and blood lipids in
adolescents: the Quebec Family Study. J.Adolesc.Health 2003
Sep;33(3):147-53.
- Boreham CA, Ferreira I, Twisk JW, Gallagher AM,
Savage MJ, Murray LJ. Cardiorespiratory fitness, physical activity, and
arterial stiffness: the Northern Ireland Young Hearts Project. Hypertension
2004 Nov;44(5):721-6.
- Platat C, Wagner A, Klumpp T, Schweitzer B,
Simon C. Relationships of physical activity with metabolic syndrome features
and low-grade inflammation in adolescents. Diabetologia 2006
Sep;49(9):2078-85.
- Andersen LB, Harro M, Sardinha LB, Froberg K,
Ekelund U, Brage S, Anderssen SA. Physical activity and clustered
cardiovascular risk in children: a cross-sectional study (The European Youth
Heart Study). Lancet 2006 Jul 22;368(9532):299-304.
- Wennlof AH, Yngve A, Nilsson TK, Sjostrom M.
Serum lipids, glucose and insulin levels in healthy schoolchildren aged 9 and
15 years from Central Sweden: reference values in relation to biological,
social and lifestyle factors. Scand.J.Clin.Lab Invest 2005;65(1):65-76.
- Ondrak KS, McMurray RG, Bangdiwala SI, Harrell
JS. Influence of aerobic power and percent body fat on cardiovascular disease
risk in youth. J.Adolesc.Health 2007 Aug;41(2):146-52.
- Krekoukia M, Nassis GP, Psarra G, Skenderi K,
Chrousos GP, Sidossis LS. Elevated total and central adiposity and low physical
activity are associated with insulin resistance in children. Metabolism 2007
Feb;56(2):206-13.
- Gutin B, Johnson MH, Humphries MC,
Hatfield-Laube JL, Kapuku GK, Allison JD, Gower BA, Daniels SR, Barbeau P.
Relationship of visceral adiposity to cardiovascular disease risk factors in
black and white teens. Obesity.(Silver.Spring) 2007 Apr;15(4):1029-35.
- Craig SB, Bandini LG, Lichtenstein AH, Schaefer
EJ, Dietz WH. The impact of physical activity on lipids, lipoproteins, and
blood pressure in preadolescent girls. Pediatrics 1996 Sep;98(3 Pt
1):389-95.
- Schmitz KH, Jacobs DR, Jr., Hong CP, Steinberger
J, Moran A, Sinaiko AR. Association of physical activity with insulin
sensitivity in children. Int.J.Obes.Relat Metab Disord. 2002
Oct;26(10):1310-6.
- Bunt JC, Salbe AD, Harper IT, Hanson RL,
Tataranni PA. Weight, adiposity, and physical activity as determinants of an
insulin sensitivity index in pima Indian children. Diabetes Care 2003
Sep;26(9):2524-30.
- Brage S, Wedderkopp N, Ekelund U, Franks PW,
Wareham NJ, Andersen LB, Froberg K. Features of the metabolic syndrome are
associated with objectively measured physical activity and fitness in Danish
children: the European Youth Heart Study (EYHS). Diabetes Care 2004
Sep;27(9):2141-8.
- Hussey J, Bell C, Bennett K, O'Dwyer J, Gormley
J. Relationship between the intensity of physical activity, inactivity,
cardiorespiratory fitness and body composition in 7-10-year-old Dublin
children. Br.J.Sports Med. 2007 May;41(5):311-6.
- Imperatore G, Cheng YJ, Williams DE, Fulton J,
Gregg EW. Physical activity, cardiovascular fitness, and insulin sensitivity
among U.S. adolescents: the National Health and Nutrition Examination Survey,
1999-2002. Diabetes Care 2006 Jul;29(7):1567-72.
- Gidding SS, Barton BA, Dorgan JA, Kimm SY,
Kwiterovich PO, Lasser NL, Robson AM, Stevens VJ, Van HL, Simons-Morton DG.
Higher self-reported physical activity is associated with lower systolic blood
pressure: the Dietary Intervention Study in Childhood (DISC). Pediatrics 2006
Dec;118(6):2388-93.
- Goodman E, Dolan LM, Morrison JA, Daniels SR.
Factor analysis of clustered cardiovascular risks in adolescence: obesity is
the predominant correlate of risk among youth. Circulation 2005 Apr
19;111(15):1970-7.
- Benson AC, Torode ME, Singh MA. Muscular
strength and cardiorespiratory fitness is associated with higher insulin
sensitivity in children and adolescents. Int.J.Pediatr.Obes.
2006;1(4):222-31.
- Rimmer JH, Looney MA. Effects of an aerobic
activity program on the cholesterol levels of adolescents. Res.Q.Exerc.Sport
1997 Mar;68(1):74-9.
- Ferguson MA, Gutin B, Le NA, Karp W, Litaker M,
Humphries M, Okuyama T, Riggs S, Owens S. Effects of exercise training and its
cessation on components of the insulin resistance syndrome in obese children.
Int.J.Obes.Relat Metab Disord. 1999 Aug;23(8):889-95.
- Kang HS, Gutin B, Barbeau P, Owens S, Lemmon CR,
Allison J, Litaker MS, Le NA. Physical training improves insulin resistance
syndrome markers in obese adolescents. Med.Sci.Sports Exerc. 2002
Dec;34(12):1920-7.
- Meyer AA, Kundt G, Lenschow U, Schuff-Werner P,
Kienast W. Improvement of early vascular changes and cardiovascular risk
factors in obese children after a six-month exercise program.
J.Am.Coll.Cardiol. 2006 Nov 7;48(9):1865-70.
- Balagopal P, George D, Patton N, Yarandi H,
Roberts WL, Bayne E, Gidding S. Lifestyle-only intervention attenuates the
inflammatory state associated with obesity: a randomized controlled study in
adolescents. J.Pediatr. 2005 Mar;146(3):342-8.
- Rosenbaum M, Nonas C, Weil R, Horlick M, Fennoy
I, Vargas I, Kringas P. School-based intervention acutely improves insulin
sensitivity and decreases inflammatory markers and body fatness in junior high
school students. J.Clin.Endocrinol.Metab 2007 Feb;92(2):504-8.
- Kahle EB, Zipf WB, Lamb DR, Horswill CA, Ward
KM. Association between mild, routine exercise and improved insulin dynamics
and glucose control in obese adolescents. Int.J.Sports Med. 1996
Jan;17(1):1-6.
- Hanai T, Takada H, Nagashima M, Kuwano T, Iwata
H. Effects of exercise for 1 month on serum lipids in adolescent females.
Pediatr.Int. 1999 Jun;41(3):253-9.
- Nassis GP, Papantakou K, Skenderi K,
Triandafillopoulou M, Kavouras SA, Yannakoulia M, Chrousos GP, Sidossis LS.
Aerobic exercise training improves insulin sensitivity without changes in body
weight, body fat, adiponectin, and inflammatory markers in overweight and obese
girls. Metabolism 2005 Nov;54(11):1472-9.
- Carrel AL, Clark RR, Peterson SE, Nemeth BA,
Sullivan J, Allen DB. Improvement of fitness, body composition, and insulin
sensitivity in overweight children in a school-based exercise program: a
randomized, controlled study. Arch.Pediatr.Adolesc.Med. 2005
Oct;159(10):963-8.
- Carrel AL, Clark RR, Peterson S, Eickhoff J,
Allen DB. School-based fitness changes are lost during the summer vacation.
Arch.Pediatr.Adolesc.Med. 2007 Jun;161(6):561-4.
- Rowland TW, Martel L, Vanderburgh P, Manos T,
Charkoudian N. The influence of short-term aerobic training on blood lipids in
healthy 10-12 year old children. Int.J.Sports Med. 1996 Oct;17(7):487-92.
- Tolfrey K, Jones AM, Campbell IG.
Lipid-lipoproteins in children: an exercise dose-response study. Med.Sci.Sports
Exerc. 2004 Mar;36(3):418-27.
- Gutin B, Yin Z, Humphries MC, Barbeau P.
Relations of moderate and vigorous physical activity to fitness and fatness in
adolescents. Am.J.Clin.Nutr. 2005 Apr;81(4):746-50.
- Patrick K, Norman GJ, Calfas KJ, Sallis JF,
Zabinski MF, Rupp J, Cella J. Diet, physical activity, and sedentary behaviors
as risk factors for overweight in adolescence. Arch.Pediatr.Adolesc.Med. 2004
Apr;158(4):385-90.
- Ruiz JR, Rizzo NS, Hurtig-Wennlof A, Ortega FB,
Warnberg J, Sjostrom M. Relations of total physical activity and intensity to
fitness and fatness in children: the European Youth Heart Study.
Am.J.Clin.Nutr. 2006 Aug;84(2):299-303.
- Stallmann-Jorgensen IS, Gutin B, Hatfield-Laube
JL, Humphries MC, Johnson MH, Barbeau P. General and visceral adiposity in
black and white adolescents and their relation with reported physical activity
and diet. Int.J.Obes.(Lond) 2007 Apr;31(4):622-9.
- Turner CH, Robling AG. Designing exercise
regimens to increase bone strength. Exerc.Sport Sci.Rev. 2003
Jan;31(1):45-50.
- Heaney RP, Abrams S, wson-Hughes B, Looker A,
Marcus R, Matkovic V, Weaver C. Peak bone mass. Osteoporos.Int.
2000;11(12):985-1009.
- McKay HA, MacLean L, Petit M, Kelvie-O'Brien K,
Janssen P, Beck T, Khan KM. "Bounce at the Bell": a novel program of short
bouts of exercise improves proximal femur bone mass in early pubertal children.
Br.J.Sports Med. 2005 Aug;39(8):521-6.
- MacDonald HM, Kontulainen SA, Khan KM, McKay HA.
Is a school-based physical activity intervention effective for increasing
tibial bone strength in boys and girls? J.Bone Miner.Res. 2007
Mar;22(3):434-46.
- MacKelvie KJ, Petit MA, Khan KM, Beck TJ, McKay
HA. Bone mass and structure are enhanced following a 2-year randomized
controlled trial of exercise in prepubertal boys. Bone 2004
Apr;34(4):755-64.
- Fuchs RK, Snow CM. Gains in hip bone mass from
high-impact training are maintained: a randomized controlled trial in children.
J.Pediatr. 2002 Sep;141(3):357-62.
- McKay HA, Petit MA, Schutz RW, Prior JC, Barr
SI, Khan KM. Augmented trochanteric bone mineral density after modified
physical education classes: a randomized school-based exercise intervention
study in prepubescent and early pubescent children. J.Pediatr. 2000
Feb;136(2):156-62.
- MacKelvie KJ, McKay HA, Petit MA, Moran O, Khan
KM. Bone mineral response to a 7-month randomized controlled, school-based
jumping intervention in 121 prepubertal boys: associations with ethnicity and
body mass index. J.Bone Miner.Res. 2002 May;17(5):834-44.
- Specker B, Binkley T. Randomized trial of
physical activity and calcium supplementation on bone mineral content in 3- to
5-year-old children. J.Bone Miner.Res. 2003 May;18(5):885-92.
- Blimkie CJ, Rice S, Webber CE, Martin J, Levy D,
Gordon CL. Effects of resistance training on bone mineral content and density
in adolescent females. Can.J.Physiol Pharmacol. 1996 Sep;74(9):1025-33.
- Arnett MG, Lutz B. Effects of rope-jump training
on the os calcis stiffness index of postpubescent girls. Med.Sci.Sports Exerc.
2002 Dec;34(12):1913-9.
- Bailey DA, McKay HA, Mirwald RL, Crocker PR,
Faulkner RA. A six-year longitudinal study of the relationship of physical
activity to bone mineral accrual in growing children: the university of
Saskatchewan bone mineral accrual study. J.Bone Miner.Res. 1999
Oct;14(10):1672-9.
- Bradney M, Pearce G, Naughton G, Sullivan C,
Bass S, Beck T, Carlson J, Seeman E. Moderate exercise during growth in
prepubertal boys: changes in bone mass, size, volumetric density, and bone
strength: a controlled prospective study. J.Bone Miner.Res. 1998
Dec;13(12):1814-21.
- Fuchs RK, Bauer JJ, Snow CM. Jumping improves
hip and lumbar spine bone mass in prepubescent children: a randomized
controlled trial. J.Bone Miner.Res. 2001 Jan;16(1):148-56.
- Morris FL, Naughton GA, Gibbs JL, Carlson JS,
Wark JD. Prospective ten-month exercise intervention in premenarcheal girls:
positive effects on bone and lean mass. J.Bone Miner.Res. 1997
Sep;12(9):1453-62.
- Iuliano-Burns S, Saxon L, Naughton G, Gibbons K,
Bass SL. Regional specificity of exercise and calcium during skeletal growth in
girls: a randomized controlled trial. J.Bone Miner.Res. 2003
Jan;18(1):156-62.
- Witzke KA, Snow CM. Effects of plyometric jump
training on bone mass in adolescent girls. Med.Sci.Sports Exerc. 2000
Jun;32(6):1051-7.
- Heinonen A, Sievanen H, Kannus P, Oja P,
Pasanen M, Vuori I. High-impact exercise and bones of growing girls: a 9-month
controlled trial. Osteoporos.Int. 2000;11(12):1010-7.
- Nichols DL, Sanborn CF, Love AM. Resistance
training and bone mineral density in adolescent females. J.Pediatr. 2001
Oct;139(4):494-500.
- Stear SJ, Prentice A, Jones SC, Cole TJ. Effect
of a calcium and exercise intervention on the bone mineral status of
16-18-y-old adolescent girls. Am.J.Clin.Nutr. 2003 Apr;77(4):985-92.
- Birmaher B, Ryan ND, Williamson DE, Brent DA,
Kaufman J, Dahl RE, Perel J, Nelson B. Childhood and adolescent depression: a
review of the past 10 years. Part I. J.Am.Acad.Child Adolesc.Psychiatry 1996
Nov;35(11):1427-39.
- Kessler RC, Walters EE. Epidemiology of
DSM-III-R major depression and minor depression among adolescents and young
adults in the National Comorbidity Survey. Depress.Anxiety.
1998;7(1):3-14.
- Motl RW, Birnbaum AS, Kubik MY, Dishman RK.
Naturally occurring changes in physical activity are inversely related to
depressive symptoms during early adolescence. Psychosom.Med. 2004
May;66(3):336-42.
- Parfitt G, Eston RG. The relationship between
children's habitual activity level and psychological well-being. Acta Paediatr.
2005 Dec;94(12):1791-7.
- Field T, Diego M, Sanders CE. Exercise is
positively related to adolescents' relationships and academics. Adolescence
2001;36(141):105-10.
- Annesi JJ. Correlations of depression and total
mood disturbance with physical activity and self-concept in preadolescents
enrolled in an after-school exercise program. Psychol.Rep. 2005 Jun;96(3 Pt
2):891-8.
- Pastor Y, Balaguer I, Pons D, Garcia-Merita M.
Testing direct and indirect effects of sports participation on perceived health
in Spanish adolescents between 15 and 18 years of age. J.Adolesc. 2003
Dec;26(6):717-30.
- Kirkcaldy BD, Shephard RJ, Siefen RG. The
relationship between physical activity and self-image and problem behaviour
among adolescents. Soc.Psychiatry Psychiatr.Epidemiol. 2002
Nov;37(11):544-50.
- Nabkasorn C, Miyai N, Sootmongkol A, Junprasert
S, Yamamoto H, Arita M, Miyashita K. Effects of physical exercise on
depression, neuroendocrine stress hormones and physiological fitness in
adolescent females with depressive symptoms. Eur.J.Public Health 2006
Apr;16(2):179-84.
- Tao FB, Xu ML, Kim SD, Sun Y, Su PY, Huang K.
Physical activity might not be the protective factor for health risk behaviours
and psychopathological symptoms in adolescents. J.Paediatr.Child Health 2007
Nov;43(11):762-7.
- Larun L, Nordheim LV, Ekeland E, Hagen KB,
Heian F. Exercise in prevention and treatment of anxiety and depression among
children and young people. Cochrane.Database.Syst.Rev. 2006;3:CD004691.
- DeBate RD, Thompson SH. Girls on the Run:
improvements in self-esteem, body size satisfaction and eating
attitudes/behaviors. Eat.Weight.Disord. 2005 Mar;10(1):25-32.
- Dishman RK, Hales DP, Pfeiffer KA, Felton GA,
Saunders R, Ward DS, Dowda M, Pate RR. Physical self-concept and self-esteem
mediate cross-sectional relations of physical activity and sport participation
with depression symptoms among adolescent girls. Health Psychol. 2006
May;25(3):396-407.
- Sagatun A, Sogaard AJ, Bjertness E, Selmer R,
Heyerdahl S. The association between weekly hours of physical activity and
mental health: a three-year follow-up study of 15-16-year-old students in the
city of Oslo, Norway. BMC.Public Health 2007;7(147):155.
- Daley AJ, Copeland RJ, Wright NP, Roalfe A,
Wales JK. Exercise therapy as a treatment for psychopathologic conditions in
obese and morbidly obese adolescents: a randomized, controlled trial.
Pediatrics 2006 Nov;118(5):2126-34.
- Ekeland E, Heian F, Hagen KB, Abbott J,
Nordheim L. Exercise to improve self-esteem in children and young people.
Cochrane.Database.Syst.Rev. 2004;(1):CD003683.
- Sallis JF, McKenzie TL, Kolody B, Lewis M,
Marshall S, Rosengard P. Effects of health-related physical education on
academic achievement: project SPARK. Res.Q.Exerc.Sport 1999
Jun;70(2):127-34.
- Coe DP, Pivarnik JM, Womack CJ, Reeves MJ,
Malina RM. Effect of physical education and activity levels on academic
achievement in children. Med.Sci.Sports Exerc. 2006 Aug;38(8):1515-9.
- Davis CL, Tomporowski PD, Boyle CA, Waller JL,
Miller PH, Naglieri JA, Gregoski M. Effects of aerobic exercise on overweight
children's cognitive functioning: a randomized controlled trial.
Res.Q.Exerc.Sport 2007 Dec;78(5):510-9.
- Strong WB, Malina RM, Blimkie CJ, Daniels SR,
Dishman RK, Gutin B, Hergenroeder AC, Must A, Nixon PA, Pivarnik JM, et al.
Evidence based physical activity for school-age youth. J.Pediatr. 2005
Jun;146(6):732-7.
- Brosnahan J, Steffen LM, Lytle L, Patterson J,
Boostrom A. The relation between physical activity and mental health among
Hispanic and non-Hispanic white adolescents. Arch.Pediatr.Adolesc.Med. 2004
Aug;158(8):818-23.
- Larson RW, Hansen DM, Moneta G. Differing
profiles of developmental experiences across types of organized youth
activities. Dev.Psychol. 2006 Sep;42(5):849-63.
- Taras H. Physical activity and student
performance at school. J.Sch Health 2005 Aug;75(6):214-8.
- Tomporowski PD, Davis CM, Miller PH, Naglieri
JA. Exercise and children's intelligence, cognition, and academic
achievement
40. Educ.Psychol.Rev. 2007.
- Mahar MT, Murphy SK, Rowe DA, Golden J, Shields
AT, Raedeke TD. Effects of a classroom-based program on physical activity and
on-task behavior. Med.Sci.Sports Exerc. 2006 Dec;38(12):2086-94.
top of page
Continue to G10. Adverse Events
Back to G8. Mental Health
Back to Physical Activity Guidelines Advisory Committee Report
Last revised: June 11, 2008
|