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DOI: 10.1542/peds.2006-1087
2006;118;e1831Pediatrics
Brian A. Walker, Dieter Heinz and James A. Levine
Lorraine Lanningham-Foster, Teresa B. Jensen, Randal C. Foster, Aoife B. Redmond,
Time for Children
Energy Expenditure of Sedentary Screen Time Compared With Active Screen
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of Pediatrics. All rights reserved. Print ISSN: 0031-4005. Online ISSN: 1098-4275.
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published, and trademarked by the American Academy of Pediatrics, 141 Northwest Point
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ARTICLE
Energy Expenditure of Sedentary Screen Time
Compared With Active Screen Time for Children
Lorraine Lanningham-Foster, PhD
a
, Teresa B. Jensen, MD
b
, Randal C. Foster, BS
a
, Aoife B. Redmond, MBBCh
b
, Brian A. Walker, DO
b
,
Dieter Heinz, MD
b
, James A. Levine, MD, PhD
a
a
Endocrine Research Unit and
b
Department of Family Medicine, Mayo Clinic, Rochester, Minnesota
The authors have indicated they have no financial relationships relevant to this article to disclose.
ABSTRACT
OBJECTIVE. We examined the effect of activity-enhancing screen devices on children’s
energy expenditure compared with performing the same activities while seated.
Our hypothesis was that energy expenditure would be significantly greater when
children played activity-promoting video games, compared with sedentary video
games.
METHODS. Energy expenditure was measured for 25 children aged 8 to 12 years, 15
of whom were lean, while they were watching television seated, playing a tradi-
tional video game seated, watching television while walking on a treadmill at 1.5
miles per hour, and playing activity-promoting video games.
RESULTS. Watching television and playing video games while seated increased energy
expenditure by 20 ⫾ 13% and 22 ⫾ 12% above resting values, respectively. When
subjects were walking on the treadmill and watching television, energy expendi-
ture increased by 138 ⫾ 40% over resting values. For the activity-promoting video
games, energy expenditure increased by 108 ⫾ 40% with the EyeToy (Sony
Computer Entertainment) and by 172 ⫾ 68% with Dance Dance Revolution
Ultramix 2 (Konami Digital Entertainment).
CONCLUSIONS. Energy expenditure more than doubles when sedentary screen time is
converted to active screen time. Such interventions might be considered for
obesity prevention and treatment.
www.pediatrics.org/cgi/doi/10.1542/
peds.2006-1087
doi:10.1542/peds.2006-1087
Drs Lanningham-Foster and Levine and Mr
Foster had full access to all of the data in
the study and take responsibility for the
integrity of the data and the accuracy of
the data analysis.
Key Words
physical activity, obesity, indirect
calorimetry, television, video games
Abbreviation
REE—resting energy expenditure
Accepted for publication Jul 13, 2006
Address correspondence to James A. Levine,
MD, PhD, Endocrine Research Unit, 5-194
Joseph, Mayo Clinic, 200 First St, SW,
Rochester, MN 55905. E-mail: levine.james@
mayo.edu
PEDIATRICS (ISSN Numbers: Print, 0031-4005;
Online, 1098-4275). Copyright © 2006 by the
American Academy of Pediatrics
PEDIATRICS Volume 118, Number 6, December 2006 e1831
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O
BESITY PREVALENCE AMONG children is at the high-
est levels measured; presently 15% of US boys and
girls 6 to 11 years of age are overweight.
1
Obesity among
children has increased more rapidly in the past 30 years.
Obesity is a global epidemic with unheralded health
consequences.
2
These increasing obesity rates have been
blamed, in part, on increasing sedentariness.
3
Sitting in
front of a television, video game, or computer screen has
been associated consistently with low levels of physical
activity.
4
Weekly screen time for children is as high as 55
hours/week,
5
and the average home in the United States
has a television on for 8 hours per day.
6
Although many
programs have attempted to separate children from the
screen, these activities are highly valued and children
are resistant to relinquishing them.
7
An alternative ap-
proach is to examine whether sedentary screen time can
be converted into active screen time.
Several activity-promoting video games directed at
children exist and have the potential to promote physical
activity during screen time.
8
A key question is whether
these activities are sufficiently exothermic to result in
increased energy expenditure. On one hand, if these
activity-promoting maneuvers increase energy expendi-
ture only minimally, then their applicability for revers-
ing sedentariness would be limited and these approaches
would offer false promise. On the other hand, if ap-
proaches to render screen time active increase energy
expenditure substantially, then they could become po-
tent tools for reversing sedentariness while permitting
highly valued screen-based activities. In this study, we
examined the energy expenditures of approaches that
render screen time active and compared these values
with values for activities performed seated among chil-
dren.
METHODS
Subjects
Twenty-five healthy children (12 boys and 13 girls) of
varying heights and weights were recruited (Table 1).
Ten children (5 boys and 5 girls) with mild obesity (85th
percentile ⱕ BMI ⱕ 99th percentile) were recruited
(Table 1). The remaining children (7 boys and 8 girls)
were of normal weight (5th percentile ⬍ BMI ⬍ 85th
percentile). The children underwent clinical evaluations
and physical examinations. Each child’s weight and
height were measured with a calibrated digital scale
(Scale-Tronix 5005 stand-on scale; Scale-Tronix, White
Plains, NY) and a fixed stadiometer, respectively. BMI
percentiles and z scores were determined by using Cen-
ters for Disease Control and Prevention growth charts.
Children who had acute or chronic diseases or were
receiving any medications were excluded. The study was
approved by the Mayo Clinic Pediatric and Adolescent
Medicine Research Committee and the institutional re-
view board. Informed written assent was obtained from
the children, and informed written consent was ob-
tained from the parents.
Procedures
Energy Expenditure
Energy expenditure was measured by using a high-pre-
cision, flow-over, indirect calorimeter built specifically
for use with children (Columbus Instruments, Colum-
bus, OH).
9
Expired air was collected with a dilution
facemask that was designed for use with children and
that covered the entire face. A primary gas standard
(0.50% carbon dioxide, 20.5% oxygen, and balanced
nitrogen) was used for gas calibrations before each mea-
TABLE 1 Characteristics of Lean and Overweight Study Participants and Mean Energy Expenditure
During Each Activity
Group
(n ⫽ 25)
Lean
(n ⫽ 15)
Overweight
(n ⫽ 10)
Age, mean ⫾ SD, y 9.7 ⫾ 1.6 9.9 ⫾ 1.7 9.4 ⫾ 1.5
Height, mean ⫾ SD, cm 144.2 ⫾ 11.2 145.9 ⫾ 12.8 141.7 ⫾ 8.5
Gender, male/female, n 12/13 7/8 5/5
Weight, mean ⫾ SD, kg 40.8 ⫾ 10.1 37.9 ⫾ 9.5 45.3 ⫾ 9.7
BMI, mean ⫾ SD, kg/m
2
20 ⫾ 418⫾ 223⫾ 4
BMI percentile, mean ⫾ SD 71.5 ⫾ 24.7 57.6 ⫾ 23.2 91.7 ⫾ 4.5
BMI z score, mean ⫾ SD 0.73 ⫾ 0.97 0.15 ⫾ 0.77 1.60 ⫾ 0.46
Energy expenditure, mean ⫾ SD, kJ/h per kg
body weight
REE 6.47 ⫾ 1.18 6.93 ⫾ 1.22 5.80 ⫾ 0.67
a
Sitting and watching television 7.73 ⫾ 1.43 8.19 ⫾ 1.47 6.97 ⫾ 1.05
b
Walking and watching television 15.08 ⫾ 2.10 14.95 ⫾ 2.18 15.25 ⫾ 2.14
Playing sedentary video game 7.85 ⫾ 1.51 8.36 ⫾ 1.68 7.14 ⫾ 0.97
c
Playing activity-promoting video game EyeToy 13.61 ⫾ 4.20 14.57 ⫾ 4.62 12.18 ⫾ 3.15
Playing activity-promoting video game Dance
Dance Revolution
17.26 ⫾ 4.28 16.76 ⫾ 3.99 18.10 ⫾ 4.75
a
Significantly lower, compared with lean children, P ⬍ .02.
b
Significantly lower, compared with lean children, P ⬍ .03.
c
Significantly lower, compared with lean children, P ⬍ .05.
e1832 LANNINGHAM-FOSTER et al
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surement. Data were collected every 30 seconds and
stored on a personal computer. Weekly alcohol burn
experiments showed carbon dioxide and oxygen recov-
eries of ⱖ99%.
Video Game Systems and Games
In the children’s study, 2 video game systems were used
(PlayStation 2; Sony Computer Entertainment, San Ma-
teo, CA, and Xbox; Microsoft, Redmond, WA). Three
video games were used, namely, 1 video game played
while seated and 2 activity-promoting video games. The
video game that was played while seated used a hand-
held controller connected by a cable to the game system
(PlayStation 2) and was called Disney’s Extreme Skate
Adventure (Activision, Los Angeles, CA). The first activ-
ity-promoting video game used a small USB camera
(EyeToy; Sony) to place the child into the game, to catch
objects interactively, for example (Nicktoons Movin’;
THQ, Calabasas Hills, CA; PlayStation 2 format). The
second activity-promoting video game used a floor
dance pad as the game controller, with children dancing
in a certain format to gain points (Dance Dance Revo-
lution Ultramix 2; Konami Digital Entertainment, Red-
wood City, CA; Xbox format).
All of the games were rated E (for everyone) by the
Entertainment Software Rating Board and were shown
to the parents for approval during the screening visit.
During the study, all children played the same video
games with the same game settings. (1) For Disney’s
Extreme Skate Adventure, all children played with the
character Woody and started the game in Andy’s room.
(2) For Nicktoons Movin’, all children played the Jelly-
fish Jam game repeatedly. (3) For Dance Dance Revolu-
tion Ultramix 2, all children played to the song “Samba”
in the training mode, with the game speed set at level 3.
Protocol
First, children attended a screening visit, in which chil-
dren and parents were familiarized with the calorimeter
and all procedures. On the day of the study, children
were asked to come to the General Clinical Research
Center. Children were instructed to arrive after ⱖ5
hours of fasting, although they were allowed water.
The child rested in a dimly lit room for 30 minutes.
Resting energy expenditure (REE) was then measured
for 20 minutes by using indirect calorimetry, as de-
scribed above. During the REE measurement, the child
was awake, semirecumbent (10° head bed tilt), lightly
clothed, and in thermal comfort (68 –74°F), in a dimly lit
room. The child was encouraged not to talk or to move
during the REE measurement.
After measurement of REE, the child was given a
snack, to reduce hunger and irritation. After the snack,
the child was directed to sit motionless for 15 minutes
while being supervised. Children watched an age-appro-
priate videotape while sitting. Energy expenditure was
then measured for 15 minutes as described above. The
indirect calorimeter mask was removed, and the child
was allowed to rest for 5 minutes.
The child was allowed to play the traditional video
game (Disney’s Extreme Skate Adventure) for ⬃3 min-
utes, to become familiar with the game. Energy expen-
diture was then measured for 15 minutes while the child
played the traditional video game while seated. The
calorimeter mask was removed, and the child was al-
lowed to rest for 5 minutes.
The child then watched a videotape (rated G) while
walking on a treadmill at 1.5 miles/hour. This is a ve-
locity that we showed previously was an enjoyable self-
selected velocity for children of this age.
9
Energy expen-
diture was measured for 15 minutes as described above.
The child then rested for 5 minutes.
The child was then allowed to play the first activity-
promoting video game (Nicktoons Movin’) for 3 minutes
for familiarization. Energy expenditure was measured
for 15 minutes while the child played the game. After a
5-minute rest, the second activity-promoting video
game (Dance Dance Revolution Ultramix 2) was played.
After 3 minutes for familiarization, energy expenditure
was measured for 15 minutes while the child played the
game. Children were allowed to drink water during the
rest period.
Statistical Analyses
Values are expressed as mean ⫾ SD. Height, weight, age,
gender, BMI, and energy expenditure were calculated
for each participant. To address our hypothesis that en-
ergy expenditure would be significantly greater when
children played interactive video games, compared with
sedentary video games, energy expenditures determined
by using indirect calorimetry while children played the 3
video games were compared numerically. To compare
changes in energy expenditure, analyses of variance
with posthoc paired t tests (Tukey-Kramer) were used.
Statistical analyses were conducted with StatView 5.0
(SAS Institute, Cary, NC).
RESULTS
All children in the study tolerated the protocol well and
enjoyed participating in the study. Characteristics of the
children are presented in Table 1. For the entire group,
the children (10 ⫾ 2 years of age; 12 boys and 13 girls)
were of varying height (144 ⫾ 11 cm) and weight (41 ⫾
10 kg); BMI was 20 ⫾ 4 kg/m
2
. Fifteen of the children
were considered lean, according to their BMI (15th per-
centile ⬍ BMI ⬍ 85th percentile; mean BMI percentile:
58 ⫾ 23; mean BMI z score: 0.15 ⫾ 0.77), and 10
children were overweight or at risk for overweight (BMI
of ⱖ85th percentile; mean BMI percentile: 92 ⫾ 5; mean
BMI z score: 1.6 ⫾ 0.5). Twenty-two children were
white/not of Hispanic origin, 2 children were Asian, and
1 child was black/not of Hispanic origin.
PEDIATRICS Volume 118, Number 6, December 2006 e1833
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Values for REE and expenditure during the various
activities (adjusted for body weight) are shown in Table
1 and Fig 1. All activities showed increased energy ex-
penditure over REE. Seated television watching and
video gaming were associated with increases of 50 ⫾ 29
kJ/hour (P ⬍ .0001) and 55 ⫾ 29 kJ/hour (P ⬍ .0001),
respectively, in energy expenditure over rest (Fig 1).
Walking while watching television increased energy
expenditure by 353 ⫾ 118 kJ/hour (P ⬍ .00001) in
comparison with REE and by 302 ⫾ 105 kJ/hour (P ⬍
.00001) in comparison with sitting and watching televi-
sion. Activity-promoting video games were associated
with a far larger increase in energy expenditure, com-
pared with playing a video game while seated. For the
EyeToy, energy expenditure increased 273 ⫾ 101 kJ/
hour above REE (P ⬍ .00001). For the Dance Dance
Revolution Ultramix 2, energy expenditure increased
382 ⫾ 181 kJ/hour above REE (P ⬍ .00001). There were
significantly greater increases in energy expenditure for
the EyeToy and Dance Dance Revolution Ultramix 2,
compared with sitting and watching television and seat-
based video gaming (P ⬍ .00001). Therefore, activity-
promoting video games are associated with substantial
increases in energy expenditure, compared with seat-
based screen activities. There were no significant differ-
ences in energy expenditure based on gender or age.
To address the hypothesis that lean children expend
more energy in playing activity-promoting video games,
compared with overweight children, we compared the
energetic responses to these seat-based and activity-pro-
moting video games between lean and overweight chil-
dren. In absolute terms, the obese children had signifi-
cantly greater increases in energy expenditure in
response to the activity-promoting video games (Fig 1).
When the data were corrected for body weight, over-
weight children had significantly lower energy expendi-
ture for resting (lean: 7.1 ⫾ 1.3 kJ/hour per kg body
weight; overweight: 5.9 ⫾ 0.8 kJ/hour per kg body
weight; P ⬍ .02), sitting and watching television (lean:
8.4 ⫾ 1.7 kJ/hour per kg body weight; overweight: 7.1 ⫾
1.3 kJ/hour per kg body weight; P ⬍ .03), and sitting and
playing the traditional video game (lean: 8.4 ⫾ 1.7 kJ/
hour per kg body weight; overweight: 7.1 ⫾ 0.8 kJ/hour
per kg body weight; P ⬍ .05) (Table 1). However the
energetic responses were not significantly different be-
tween the groups for walking and watching television or
playing the activity-promoting video games (Table 1). It
was clear that the increase in energy expenditure asso-
ciated with activity-promoting video games was intact in
obesity.
DISCUSSION
Obesity rates in children and adults have reached un-
precedented levels. Obesity-associated chronic diseases,
such as type 2 diabetes mellitus, are now commonly
being diagnosed in children and are increasing in inci-
dence in adults. One factor that is thought to be impor-
tant in obesity pathogenesis is low activity levels or low
non-exercise activity thermogenesis.
10,11
It is recognized
that an important factor in understanding sedentariness
is the many hours each day that people engage in seated
screen-based activities, such as television watching,
video gaming, and operating a computer. Our objective
in this study was to examine the energetic implications
of converting seat-based screen time to activity-based
screen time. Activity-promoting video games and tread-
mill television and computer use more than doubled
energy expenditure, compared with the chair-based
equivalents. We suggest that activity-promoting video
gaming and computer use is one potential approach for
reversing sedentariness.
Low activity levels that are coupled to, on average, 8
hours of screen time per day are widely recognized as
major factors in obesity. Many attempts have been made
to promote activity at home, at school, and in the work-
place.
12
Part of the problem is that children value screen-
FIGURE 1
Mean energetic increases above resting values for sitting
and watching a videotape or playing each video game
for lean (n ⫽ 15) and overweight (n ⫽ 10) children. Val-
ues with different letters indicate significant differences
in energetic increases. Values with the same letter were
not significantly different. Values are mean ⫾ SEM.
b
Sig-
nificantly greater increase above resting values than sit-
ting and watching a videotape or playing a traditional
video game (P ⬍ .00001).
c
Significantly greater increase
above resting values than sitting and watching a video-
tape or playing a traditional video game (P ⬍ .0001) or
playing with the EyeToy.
d
Significantly greater increase
above resting values than sitting and watching a video-
tape or playing an traditional video game (P ⬍ .0001),
playing with the EyeToy (P ⬍ .002), or walking and
watching television (P ⬍ .003).
e1834 LANNINGHAM-FOSTER et al
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based activities; therefore, attempts to have children re-
place their gaming with less-valued activities, such as
walking in the park, often fail.
13,14
If sedentary screen
time could be converted effectively to activity, then this
could be an effective approach for promoting physical
activity. Our question was whether activity-promoting
screen time increases energy expenditure substantially,
because this might prompt studies to examine these
modalities for weight loss.
Although our data demonstrated clearly that activity-
promoting screen time increases energy expenditure in
children dramatically, the study has limitations. First,
this was not a long-term weight loss study. Our goal was
to evaluate the energetic potential of converting seden-
tary screen time to activity-promoting screen time. We
think that these data are sufficiently robust to warrant
prospective, randomized studies in this area. Second, the
experiments were conducted in a laboratory, rather than
at home. We do not think that a home-based study
would have altered substantially our primary finding
that activity-promoting screen time doubles energy ex-
penditure, compared with seat-based screen time. Our
study was relatively small; however, it was conducted
very carefully, so that a larger study would have been
unlikely to alter the primary findings. We did not ran-
domize the order of the study protocol between study
participants. Randomization of the protocol activities
would have extended the length of the study protocol
from 3 hours to 6 hours, making it more difficult for
young children to participate. Finally, the children re-
ceived a small snack, which might have increased energy
expenditure above REE by ⬃5%. This was ethically
mandatory to prevent the children from feeling exces-
sively hungry. It did not affect our primary results. De-
spite the limitations, it is clear that activity-promoting
video games can increase screen-associated energy ex-
penditure dramatically.
CONCLUSIONS
Activity-promoting video games have the potential to
increase energy expenditure in children to a degree sim-
ilar to that of traditional playtime.
15,16
Classic behavior
models and large numbers of video-gaming units and
computers suggest that children are spending more time
in front of screens than they did previously. Further-
more, projections indicate that screen time for children
is likely to continue to increase, rather than decrease.
We think that converting seat-based screen time to ac-
tivity-associated screen time is an essential approach for
promoting an active environment that is also fun for
children.
ACKNOWLEDGMENTS
This work was supported by National Institutes of Health
grants DK50456, DK56650, DK63226, DK66270, and
M01-RR00585. Support was also provided by the Mayo
Clinic Department of Family Medicine Small Grants Pro-
gram.
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DOI: 10.1542/peds.2006-1087
2006;118;e1831Pediatrics
Brian A. Walker, Dieter Heinz and James A. Levine
Lorraine Lanningham-Foster, Teresa B. Jensen, Randal C. Foster, Aoife B. Redmond,
Time for Children
Energy Expenditure of Sedentary Screen Time Compared With Active Screen
Services
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