The relationship among television watching, physical activity, and body composition of young children.
OBJECTIVE
Television watching has been reported to be associated with obesity, resting energy expenditure, and lower daily physical activity among both children and adolescents. However, most of these studies were based on self report or data collected in laboratory settings. This study examined the relationship among observed time of television watching, observed physical activity level and body composition among 3- or 4-year-old children.


METHODS
African-American (41.4%), Mexican-American (23%), and Anglo-American (35.6%) children (N = 191, males = 90) from the Texas site of the Studies of Child Activity and Nutrition program were observed from 6 to 12 hours per day up to 4 days over 1 year. Activity level each minute of the day was measured with the Children's Activity Rating Scale (interobserver reliability = .84 +/- .001). The interobserver reliability of time of television watching was .96 +/- .08.


RESULTS
The median of the longest number of consecutive minutes of television watching was 15 (range = 1 to 79). The median percent of minutes of television watching of total observed minutes was 14.8% (0% to 58%) and the median percent of minutes of inside minutes was 17.9% (0% to 80.9%). There were no gender or ethnic differences in time watching television or physical activity during television watching. Physical activity during television watching was lowest during the longest bout of television watching (mean = 1.48 +/- .28) compared to outside minutes (mean = 2.38 +/- .21), inside non-television minutes (mean = 1.96 +/- .13) and inside television minutes (mean = 1.65 +/- .18). The level of physical activity during television-watching times was highest (P < .0031) during October and November and lowest during March, April, June, and July. Longest bout of television watching and percent of minutes watching television to total observed minutes were inversely associated with mean physical activity, percent of minutes of physical activity levels 3, 4, or 5, and percent of physical activity levels 4 or 5. Percent of television watching to inside minutes was negatively correlated with physical activity levels 4 or 5. Television-watching behavior was not associated with body composition.


CONCLUSIONS
Television watching was weakly negatively correlated with physical activity levels, and physical activity was lower during television-watching than non-television-watching time in this sample of children. Television viewing behavior was not associated with body composition.
DuRant
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Division of Adolescent/Young Adult Medicine, Children's Hospital, Harvard Medical School, Boston, MA 02115.
Baranowski
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Johnson
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Thompson
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D001741:Black or African American; D001823:Body Composition; D002675:Child, Preschool; D004734:Energy Metabolism; D015444:Exercise; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D017058:Mexican Americans; D009765:Obesity / Q000453:epidemiology / Q000209:etiology*; D012621:Seasons; D013690:Television; D013781:Texas / Q000453:epidemiology; D013997:Time Factors; D044465:White People