*The following is excerpted from an online article posted on HealthDay.
Over 90 percent of U.S. high school students don't get enough exercise to stay fit and healthy, and the pattern persists after they graduate, a new study finds.
The researchers followed students at 44 high schools for four years, and found that only 9 percent met current exercise recommendations throughout that time. For the most part, those habits held steady after high school -- though college students were more active than non-students.
There was also some variation among college kids, the study found: Those who lived on campus exercised more than those who lived at home.
It's not clear why those students were more active. They might have been more involved in sports, for example, or simply walked more -- running from classes to dorms and other campus buildings, said lead researcher Kaigang Li.
The study is far from the first to show that most U.S. teenagers need to move more.
According to Peter Katzmarzyk, a professor at Louisiana State University's Pennington Biomedical Research Center, in Baton Rouge, "This study really confirms the low levels of physical activity in adolescents, which appear to be maintained over time as they transition into young adulthood."
A strength of this study, he said, is that it objectively measured teens' activity levels: They wore devices called accelerometers, which tracked how much they moved over the course of a week.
The U.S. Centers for Disease Control and Prevention has long recommended that children and teenagers get at least an hour of physical activity each day. That mainly means exercise that boosts the heart rate, such as running. But, kids should also try some strength-building activities -- for example, push-ups or lifting light weights.
Studies have shown that few young people are heeding that advice, however, according to the CDC.
The new findings are based on 561 students who were followed for four years, starting in 10th grade. Over 90 percent fell short of getting an hour of exercise each day over the study period, Li's team found.
What's more, the study participants' activity levels typically declined in the year after high school graduation -- especially if they did not go to college. Those who went to a four-year college got a little more exercise, particularly if they lived on campus.
According to Li, that suggests that college life -- possibly by giving students access to gyms and other facilities -- helps young people be more active.
The study findings were published online Sept. 26 in the journal Pediatrics.