U Of M Study Shows Teens Become Less Active As They Grow Older

As they grow older, teenagers are spending more time in front of the computer and television and less time participating in physical activities, according to researchers at the University of Minnesota School of Public Health.

Research published in the journal Pediatrics found that moderate to vigorous physical activity among teenage girls and boys dramatically decreased from early to late adolescence. In addition, the findings showed that sedentary behaviors increased nearly 25-50 percent from 1999 to 2004.

"There is a disturbing shift in behavior as adolescents grow older," said Melissa Nelson, Ph.D., lead author of the study and assistant professor of epidemiology and community health at the University of Minnesota School of Public Health. "The increase in sedentary activities combined with the decrease in physical activity is thought to be associated with increased risk for obesity."

Participation in physical activity among girls dropped from 5.9 to 4.9 hours a week from early adolescence (ages 11-15) to midadolescence (ages 15-18). Even more drastic was the drop from 5.1 to 3.5 hours a week in girls from mid to late adolescence (ages 18-23). Time spent on the computer for non-school related activities also increased from 8.8 to 12.5 hours a week from mid to late adolescence.

In contrast, boys showed a more delayed decline in physical activity starting in midadolescence and dropping from 6.5 to 5.1 hours a week as they grew older. Leisure time computer use increased substantially from early to midadolescence (from 11.4 to 15.2 hours a week) and mid to late adolescence (10.4 to 14.2 hours a week). Researchers conducted a longitudinal study of more than 2,000 adolescents to examine changes in eating patterns, weight, and physical activity over five years. Subjects completed two surveys for Project EAT: Eating Among Teens - one in 1999 and one in 2004 - to determine if there were changes in physical activity patterns.

Project EAT: Eating Among Teens was designed to investigate the factors influencing the eating habits of adolescents, to determine if youth are meeting national dietary recommendations, and to explore dieting and physical activity patterns among youth. The project strives to build a greater understanding of the socioeconomic, personal, and behavioral factors associated with diet and weight-related behavior during adolescence so more effective nutrition interventions can be developed.

This study was supported by the Maternal and Child Health Program, Health Resources and Services Administration, and the Department of Health and Human Services.

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Contact: Liz Wulderk
University of Minnesota