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Sedentary teens more likely to have higher blood pressure
High BMI was associated with lower diastolic blood pressure.
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Teenagers who spend a lot of time in front of the television are more likely to have higher blood pressure, regardless of overweight.
“This is the first research to show a direct and independent connection between TV watching and higher blood pressure among adolescents,” said Nicolas Stettler, MD, a pediatric nutrition specialist at The Children’s Hospital of Philadelphia.
Stettler and colleagues reported the results of their study of 4,500 American adolescents in the Journal of Adolescent Health. They found that sedentary activities and higher BMI were associated with higher systolic blood pressure.
“It was already known that physical activity lowers blood pressure in both adults and children, but sedentary activity is not just the opposite of physical activity,” Stettler said. “For example, other studies have found that decreasing sedentary activity in young people helps prevent or treat obesity better than interventions to increase physical activity.”
NHANES data used
The researchers studied nationally representative data from 4,500 U.S. adolescents, aged 12 to 19, who participated in the 1999 to 2002 National Health and Nutrition Examination Survey. Interviewers assessed the adolescents’ nutritional intake and activities using questionnaires. Measurements of blood pressure and BMI were adjusted for gender and age.
Within the 12- to 15-year-old age group, the study team found higher blood pressure to be associated with higher levels of TV and video watching. In a model adjusted for age, sex and height using z-scores, researchers found that systolic blood pressure was 0.022 standard deviation higher per one-hour of sedentary activities (95% CI, 0.007-0.038), or the equivalent of approximately 0.2 mm Hg.
“Although the association between sedentary activity and systolic blood pressure was rather small, most adolescents spend several hours per day in sedentary activities,” said Yasuki Kobayashi, MD, PhD, professor at the University of Tokyo Department of Public Health. “Interventions to decrease sedentary activities may have an important public health impact.”
The researchers also found that higher BMI is associated with lower diastolic blood pressure, contrary to previous associations found in studies of adults. The implications of this finding are unclear, but show that adolescents are not just “small adults” and may have determinants of blood pressure that are different from adults, according to the researchers.
For more information:
- Sugiyama T, Xie D, Graham-Maar RC, et al. Dietary and lifestyle factors associated with blood pressure among U.S. adolescents. J Adolesc Health. 2007;40:166-72.