Context.— Physical inactivity contributes to weight gain in adults, but whether
this relationship is true for children of different ethnic groups is not well
established.
Objective.— To assess participation in vigorous activity and television watching
habits and their relationship to body weight and fatness in US children.
Design.— Nationally representative cross-sectional survey with an in-person interview
and medical examination.
Setting and Participants.— Between 1988 and 1994, 4063 children aged 8 through 16 years were examined
as part of the National Health and Nutrition Examination Survey III. Mexican
Americans and non-Hispanic blacks were oversampled to produce reliable estimates
for these groups.
Main Outcome Measures.— Episodes of weekly vigorous activity and daily hours of television watched,
and their relationship to body mass index and body fatness.
Results.— Eighty percent of US children reported performing 3 or more bouts of
vigorous activity each week. This rate was lower in non-Hispanic black and
Mexican American girls (69% and 73%, respectively). Twenty percent of US children
participated in 2 or fewer bouts of vigorous activity per week, and the rate
was higher in girls (26%) than in boys (17%). Overall, 26% of US children
watched 4 or more hours of television per day and 67% watched at least 2 hours
per day. Non-Hispanic black children had the highest rates of watching 4 or
more hours of television per day (42%). Boys and girls who watch 4 or more
hours of television each day had greater body fat (P<.001)
and had a greater body mass index (P<.001) than
those who watched less than 2 hours per day.
Conclusions.— Many US children watch a great deal of television and are inadequately
vigorously active. Vigorous activity levels are lowest among girls, non-Hispanic
blacks, and Mexican Americans. Intervention strategies to promote lifelong
physical activity among US children are needed to stem the adverse health
consequences of inactivity.