The biggest professional football players in America may be more likely than their fellow players to die of heart disease, even though they appear to generally enjoy a longer-than-average lifespan, according to a U.S. study.

The report in the American Journal of Cardiology followed more than 3,400 National Football League (NFL) players who were active between 1959 and 1988, and found that 334 had died by 2007 -- only about half the rate that would be expected based on U.S. norms.

But certain players, the ones who were biggest during their careers, had higher risks of dying from heart disease or stroke, with defensive linemen especially vulnerable.

The findings build on evidence that football players' big bodies can become a health liability in the long run, said Sherry Baron, a researcher at the National Institute for Occupational Safety and Health in Cincinnati, who led the study.

"I think this makes it clear that if you're big and muscular at a young age, it could have a long-term (health) effect," she said.

According to the study, defensive linemen had a 42 percent higher risk of death from cardiovascular disease compared with U.S. men in general. Of 498 defensive linemen, 41 died of cardiovascular causes.

The problem, though, is that once big athletes are no longer in the game, it's very hard to keep up their former physical activity levels, she added. Sometimes, injury can make it impossible.

The study also showed that players with a BMI of 30 or higher during their careers, which would qualify them as "obese," were twice as likely to die of cardiovascular causes as their lighter peers.

As for why the ex-players had a lower overall mortality rate than the general public, the authors said one factor was likely to be that few of them smoke, which has been shown in previous studies.

But other studies have found that after retirement, pro football players tend to have more heart risk factors, such as high blood pressure, unhealthy cholesterol levels and obesity, than the general public.

Cardiologists said the current study has some limitations.

One is that it relied on information from death certificates, which do not always give the whole picture, said Martin Goldman, a cardiologist at Mt Sinai Medical Center in New York, who has studied heart risks for NFL players.

There are also many unknowns, such as how the players' BMIs changed over time, or what kind of lifestyle they led after retirement.

Still, he agreed that the bottom line does seem to be that size matters, adding that big players need to make an effort to lose weight once they're no longer playing.

"They don't necessarily change their eating habits, even though they're not exercising as much," he said.

Both Baron and Goldman agreed that there are implications beyond the NFL, since college and high school football players tend to bulk up to play. And there is evidence this may put them at risk for heart disease later on.

"Young athletes may strive to look like the professional players, but they need to realize there could be long-term health effects," Baron added. SOURCE: http://bit.ly/xPPpyF

(Reporting from New York by Amy Norton at Reuters Health; editing by Elaine Lies and Bob Tourtellotte)