It's not just the couch potatoes and video-game jockeys.

A new study of sports physicals has shown surprisingly high rates of obesity and elevated blood pressure among Philadelphia student athletes.

Researchers at Thomas Jefferson University surveying four years of physical exam results for students ages 10 to 20 found obesity and high blood pressure appear to be as much of a problem for active kids as for their peers.

The suggestion, the researchers say, is that even participation in athletics was not enough to protect the youngsters from these health concerns.

The conclusions were based on physical examinations by the Athlete Health Organization, a nonprofit that provides physical examinations to city students who want to take part in school sports. The group's exams are given each year for free by volunteer health-care professionals.

The study, published in the current issue of the Journal of Pediatrics, found that 20 percent of participants were overweight, 24 percent were obese, and 14.8 percent had higher-than-normal blood-pressure readings.

Being overweight for children and adolescents is defined as a body mass index at or above the 85th percentile (meaning they are among the heaviest 15 percent of children) but less than the 95th percentile. Obesity is at or above the 95th percentile (the heaviest 5 percent of children), according to the Centers for Disease Control and Prevention. Normal is from the fifth percentile to under the 85th percentile.

Direct comparisons are tricky because data are collected differently. However, according to city Health Department data, the overall rate of obesity among city schoolchildren fell from 21.7 percent in 2006-07 to 20.3 percent in 2012-13.

The study's physicals were administered to about 2,700 city students over four years, from 2009 to 2012.

Pennsylvania requires pre-participation exams for student athletes.

According to the CDC, in 2011-12 about 17 percent, or nearly 13 million, of children and adolescents were classified as obese. Some estimates say the number of obese youngsters is much higher.

The national rate was highest among Hispanic children, at 22.4 percent, according to the CDC. For non-Hispanic black children, the rate was 20.2 percent; for non-Hispanic white children, the rate was 14.4 percent.

A 2012 national study found that overall, 14 percent of U.S. adolescents either had high blood pressure or were edging toward it.

In the Athlete Health Organization study, race and ethnicity data were compiled only for 2012. In that year, 71 percent of participants self-identified as African American, 16 percent as Caucasian, 7 percent Asian, 5 percent Hispanic, and 1 percent other.

Overall, 69 percent of study participants were males.

David Shipon, chief executive officer of the Athlete Health Organization and a Jefferson cardiologist, said the group's free physical program's mission for years has been to identify children with serious, undetected health problems.

The new findings about unhealthy weight and blood-pressure rates should signal the need to address these health issues, Shipon said.

"Hopefully, the mission will lead to programs that will change these patterns," he said.

Unchecked, excess weight and blood pressure can lead to serious heart disease in adulthood.

Nationally, high obesity rates among children have been linked to lower incomes. The Athlete Health Organization does not impose income limits, but many of the students who come for their services are believed to be from low-income households. Philadelphia has among the worst poverty rates of large American cities.

Jeremy Close, one of the study's authors and the doctor in charge of Jefferson's Sports Medicine Clinic, noted healthy food can be more expensive and more difficult to obtain in poor neighborhoods than less healthy alternatives.

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