America’s young people, as a group, are becoming more out of shape with every passing year, regardless of their family’s economic situation, a new study from the Centers for Disease Control and Prevention reports. The finding raises troubling questions about the future health and longevity of our children and suggests that parents and other authority figures need to find better ways to get our youth moving.
For the past few decades, accumulating data and anecdotal evidence have shown that children in the United States are becoming more sedentary. Less than a third of young people ages 12 to 18 are said to achieve the recommended levels of physical activity for their age group, which would be about an hour a day of exercise.
Instead, epidemiological studies suggest, physical activity among American youngsters peaks before age 10, and perhaps as early as 2, and begins a steady and accelerating decline after that. By some reports, children typically spend eight to 10 hours a day in front of a television or computer screen, with their screen time rising in summer, when school doesn’t interfere.
But those statistics and past epidemiological studies, though worrisome, don’t provide direct physical evidence about how aerobically fit — or not — young people might be. So, for the new study, which was published in May as a National Center for Health Statistics Data Brief, researchers with the C.D.C. turned to the huge database about American health habits known as the National Health and Nutrition Examination Survey, or Nhanes.
Intermittently in past years, C.D.C. scientists have expanded on the usual annual Nhanes telephone questioning by inviting some respondents to visit a mobile physiology lab for more extensive physical testing. And they did so again in 2012, winding up with a group of about 450 boys and girls ages 12 to 15 representing a variety of ethnic groups and socioeconomic circumstances.
The researchers had their subjects jog on a treadmill to determine cardiorespiratory fitness. Similar treadmill testing had been completed with smaller groups of young people in past years.
Then the researchers compared their volunteers’ fitness to what it should be, based on age-specific benchmarks developed recently by the C.D.C. and other institutions that researchers called the “healthy fitness zone.”
Few of the young people qualified to be in that zone. Over all, only 42 percent were as fit as they should have been, given their age, and that percentage fell precipitously among girls. Less than 34 percent of the female participants had fitness levels that would set them within the healthy fitness zone, the testing showed, compared with about 50 percent of boys.
Ethnicity and family income played no discernible role in the volunteers’ fitness, according to the data. Those from affluent families were as likely to be out of shape as those from families below the poverty line.
The findings grew bleaker when researchers compared the fitness of the group in 2012 to that of similarly aged volunteers from 1999 to 2004. The average fitness of the boys and girls, they found, had declined by about 10 percent since 2004.
“Really, this is not good news,” said Janet Fulton, a lead epidemiologist with the C.D.C’s Physical Activity and Health Branch, who oversaw the new study. “We’re talking about a better than 1 percent per year drop in cardiorespiratory fitness” among a group for whom, she said, “physical activity should come naturally.”
The potential long-term health implications for the country’s young people are disquieting, she continued. “There’s strong evidence that cardiorespiratory fitness is one of the best indicators” of lifelong health, reduced disease risk and greater longevity, she said. “So kids who are less fit when they’re young are likely to be less healthy when they’re adults.”
That message is hardly new but is worth repeating, said Gordon Blackburn, the director of cardiac rehabilitation at the Cleveland Clinic, who was not part of the new study but says he witnesses its implications every day. “Thirty years ago, we would not have expected to see 12-year-olds with symptoms of cardiac disease,” he said. “Now we’ve had to start a pediatric preventive cardiology clinic.”
The solution to the falling levels of fitness and heart health among young people is, theoretically, simple, he and Dr. Fulton agree. “Get kids moving,” Dr. Fulton said.
But in practice, this recommendation probably requires the active participation of parents or other authority figures. “Inactivity is a family issue,” Dr. Blackburn said. “If parents aren’t active, kids won’t be.”
So in the coming weeks, he said, try instituting after-work family bike rides or swim outings. Or counter the hours that your family is spending watching the World Cup with some rousing backyard games of dribble-past-Mom-as-if-she-were-standing-still.
“If it’s fun,” Dr. Blackburn said, “kids will keep doing it.”
Source: The New York Times
July 9, 2014
By Gretchen Reynolds, photo by Diane Diederich/Getty Images