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Television viewing: moderator or mediator of an adolescent physical activity intervention?
Published Web Locationhttps://doi.org/10.4278/ajhp.07053050
PurposeTo determine whether the amount of television (TV) watched by participants enrolled in a physical activity intervention mediates or moderates program effectiveness.
DesignNine-month, controlled, school-based physical activity intervention.
SettingPublic high school.
ParticipantsOne hundred twenty-two sedentary adolescent females (mean +/- standard deviation age = 15.04 +/- 0.79 years).
InterventionSupervised in-class exercise, health education, and internet-based self-monitoring.
MeasuresPhysical activity by 3-day physical activity recall; TV viewing by self-reports; cardiovascular fitness by cycle ergometer.
AnalysisT-tests were conducted to examine between-group differences. Linear regression equations tested the mediating or moderating role of TV watching relative to the intervention.
ResultsTV viewing moderated the intervention's effect on vigorous activity; the intervention significantly predicted change in physical activity among high (beta = -.45; p < .001), but not among low (p > .05), TV watchers. TV viewing did not mediate the intervention effect.
ConclusionsConsistent with displacement theory, adolescents who watched more TV prior to the intervention showed postintervention increases in vigorous physical activity and concomitant decreases in TV viewing, whereas those who watched less TV showed no change in physical activity or TV viewing.
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