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May 26, 2005

Study looks at how to make physical activity a habit

The average American child watches four or more hours of television each day, according to the Centers for Disease Control and Prevention. And 60 percent of U.S. adults are not physically active on a regular basis.

It’s become routine to hear statistics about how the American public is inactive and overweight, spending too much time in front of the television or the computer. They’re sitting too long in traffic or at work. Children may seem doomed to follow the sloth-like habits of their elders. Not necessarily, according to Deborah Aaron.

Aaron is tracking students and graduates of the Woodland Hills School District for an almost 20-year study, one of the of the longest follow-up studies of physical activity focusing on the time span of adolescence through adulthood.

An associate professor in the Department of Health and Physical Activity, School of Education, Aaron received a National Institutes of Health (NIH) grant to continue the University of Pittsburgh Physical Activity Study (PittPAS) with Woodland Hills School District graduates. Co-investigators are Robert Robertson and Elizabeth Nagle, both also in the Department of Health and Physical Activity.

Most long-term studies focus on adulthood, but Aaron said the change in activity level from the teenage years to young adulthood occurs at a critical time in people’s lives. “A lot of things happen to that age group — big life transitions,” Aaron said. “People get married, have children, go to school, start a career. And we want to see how these things impact on physical activity.”

She hopes the research project will offer insight on how to make physical activity more a part of people’s habits, whether they are 8th graders who don’t want to play baseball or 20-somethings trying to whittle down their waistlines.

The three best predictors of athletic activity for a child or an adolescent are: Enjoying the activity, competence in the activity and a support system encouraging the activity. But a child’s participation or lack of it doesn’t necessarily cast the die for the rest of their lives, according to Aaron.

“A physical act is a behavior and people are constantly changing their behavior,” she explained. “If we are going to promote a physical activity, we can’t intervene at one point and expect the effect of that intervention to have long-term impact. It has to be a constant message. People are always changing their activity patterns.”

PittPAS, begun in 1990 by Ronald LaPorte, professor of epidemiology in the Graduate School of Public Health, examined the physical activities of 1,245 pupils, aged 12 to 18. After Aaron became principal investigator of the study in 1999, she released preliminary findings from the first 10 years of the study: Physical activity decreased by 43 percent from adolescence into adulthood because the youths were spending less or no time in high intensity physical or team sport activities.

Aaron attributes the drastic drop in physical activity to the reduction in team sport activities upon finishing high school or a post-secondary education.

During the first decade of research, Aaron found that boys, aged 12 to 18, more frequently reported being on a team of a competitive nature. But the same-aged girls often cited individual or potential life-long activities such as aerobics, dance, bicycling or running. “Running is a highly reported activity among adolescent girls. Boys are most likely to report baseball, football and basketball,” she added.

If teenage girls are part of a competitive athletic team, it doesn’t seem to continue into their 20s.

“What we found is that involvement in team sport activity for women ages 22-25 is essentially zero,” she said. “That absence of activity relates back to what types of activities we are promoting to children,” Aaron explained. “Why is it that young women are not involved in team activities? There could be two explanations: No opportunities or an activity is not preferred by young women.”

The bottom line is that for all the physical activity expended in team competition, it usually doesn’t carry into adulthood.

“Those activities are very important,” Aaron said. “But we may want our schools and communities to promote other activities that people can engage in for the rest of their life such as running, aerobics, weight training, walking, dance, golf, swimming, rollerblading and bicycling.”

As Aaron continues to track the same cohort of Woodland Hills School District students, now in the their mid- to late-20s, she and her colleagues have discovered an increase in moderate intensity activities such as brisk walking as opposed to running. “We don’t know why this is happening,” said Aaron, “if it’s because of availability of an activity or a preference. But we’re trying to understand what contributes to adolescents and adults increasing or decreasing physical activity.”

Aaron plans to bring her Woodland Hills graduates into the laboratory to gauge their physiological and perceptual response to exercise. For example, the researchers will compare how strenuous an exercise really is compared to how difficult a subject thinks it is.

“A person’s perceived exertion — how they feel — can impact if somebody maintains and initiates certain physical activities. We’re testing this hypothesis and, if it’s true, part of a physical education program would help manage people’s perception of discomfort.”

—Mary Ann Thomas

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