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Young children who lead inactive lifestyles are five-to-six times more likely to
be at serious risk of heart disease, with that degree of danger emerging as
early as their teenage years, according to a new study by researchers at the
University of North Carolina at Chapel Hill.
The findings, published
Friday, April 4, in the open access journal Dynamic Medicine, looked at a group
of children twice – first while in grade school, then again seven years later
when they were in their teens.
Researchers wanted to know more about the
early onset of metabolic syndrome, a condition more commonly found in adults.
Metabolic syndrome is the label given to a clustering of medical disorders that
raise the risk of heart disease and diabetes, such as glucose intolerance,
hypertension, elevated triglycerides, low HDL (so-called “good”) cholesterol and
obesity. Previous studies have found that somewhere from four percent to nine
percent of adolescents have the condition.
However, until now, no one
had tracked the same group of children over time to see just how fitness and
activity levels in their early years played a role in the likelihood of them
developing metabolic syndrome by the time they were teenagers, said Robert
McMurray, professor in the School of Public Health’s nutrition department and professor of exercise and sports science in UNC’s College of Arts and Sciences.
The study
looked at data from almost 400 children between the ages of seven and 10 from
across North Carolina. Researchers measured factors such as height, body mass,
percentage body fat, blood pressure and cholesterol levels. Participants were
also surveyed about their physical activity and given an aerobic fitness
test.
When the same children were examined again seven years later, 4.6
percent had three or more characteristics of metabolic syndrome.
McMurray
said adolescents with the syndrome were six times more likely to have had low
aerobic fitness as children and five times more likely to have low levels of
physical activity at the time they joined the study.
For example, as
children, those who had low levels of physical activity got no vigorous exercise
(such as playing basketball or soccer) and spent less than 20 minutes a day
doing moderate-intensity physical activity (walking briskly, riding a bike at a
medium speed). That means that at best, they were getting just one-third of the
60 minutes a day that is currently recommended for children by the Centers for
Disease Control and Prevention, said McMurray.
“This shows efforts
need to begin early in childhood to increase exercise,” he said. “Children today
live a very sedentary life and are prone to obesity. This is the first study to
examine the importance of childhood fitness levels on your metabolism as a
teenager. Previously we didn’t know if low fitness levels were an influence.
“It’s obvious now that there is a link and this is something which we
need to pay attention to by encouraging our kids to keep fit, or suffer the
consequences later in life,” said McMurray.
McMurray also holds
a professorship in physical therapy in the department of exercise and sports
science, and he coordinates the Master of Arts specialization in exercise physiology.
Other authors of the study were Shrikant I. Bangdiwala, research
professor in the UNC School of Public Health’s biostatistics department; Joanne
S. Harrell, the Frances Fox Hill professor in the School of Nursing and director
of the Center for Research on Chronic Illness; and Leila D. Amorim, who at the
time the paper was written was a graduate student in the School of Public
Health’s biostatistics department and is now an assistant professor in the
statistics department at the Federal University of Bahia in Salvador,
Brazil.
The study, titled “Adolescents with metabolic syndrome have a
history of low aerobic fitness and physical activity levels,” can be found at http://www.dynamic-med.com.
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School of Public Health contact: Ramona DuBose, director of communications, (919) 966-7467 or ramona_dubose@unc.edu.
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