WEDNESDAY, Feb. 28, 2018 (HealthDay News) -- A lifetime spent playing football has been linked to brain damage, but the game also may lead to serious heart problems, two new studies suggest.
In one, researchers found that former National Football League players have a five-times greater chance of developing heart rhythm problems, such as atrial fibrillation, than the general public.
The other study found structural changes in the hearts of college football players after just one season.
In the study of NFL players, "most of these athletes' heart rates were within normal limits, and they were asymptomatic," said lead researcher Dr. Dermot Phelan. He's director of the sports cardiology center at the Cleveland Clinic in Ohio.
To find out if retired NFL players were likely to have heart problems, Phelan and his colleagues screened 460 former players and compared the findings with 925 people from the general public.
After taking into account blood pressure, weight, age and race, the investigators found that the players had a 5.5-times higher likelihood of atrial fibrillation than the nonathletes. The researchers also found other signs of abnormal electrical action in athletes' hearts.
"We saw slower heart rates with features on the ECG [electrocardiogram] consistent with slow electrical impulses and conduction," Phelan said. "This was associated with a higher rate of pacemaker implantation in the former NFL group."
He said this is the first study to show these findings in elite, primarily strength athletes.
"Atrial fibrillation is one of the most common heart rhythm disorders and can result in stroke," explained Dr. Gregg Fonarow, a spokesman for the American Heart Association and a professor of cardiology at the University of California, Los Angeles.
Earlier studies have shown that participation in long-distance running is associated with a higher risk for atrial fibrillation, he said.
"It is thought that there may be progressive scarring or enlargement of the atrial chambers in the heart resulting from the extensive exercise that contributes to the atrial fibrillation risk," said Fonarow, who wasn't involved with the studies.
Researchers for the second study reported that freshman college football players had changes to their heart after just one season of college football. That study was led by Dr. Jonathan Kim, chief of sports cardiology at Emory University in Atlanta.
Changes to the players' hearts included enlargement of the aortic root -- the place where the aorta meets the heart. It's not clear, however, if an enlarged aortic root is medically significant, according to the researchers.
For the study, Kim and his colleagues tested the electrical activity and the condition of the heart arteries in 136 freshman football players and 44 freshmen who did not play football.
After the football season, all the participants had gained weight, but only the football players showed enlargement of the aortic root, Kim said.
Although the players' aortic roots were within the normal range, their enlargement may not be the result of exercise training completely, he said.
Kim, who is also the lead cardiologist for the Atlanta Falcons, cautioned that it's unclear if these changes could affect the players' health.
"The study results also confirmed findings from previous studies -- namely that some of the football players had a tendency to develop higher systolic blood pressure and increases in vascular stiffening, all potential signs of adverse cardiovascular changes," Kim said.
The clinical significance of these findings requires further study and is currently unknown, he said.
Fonarow, however, said that "these findings suggest the extensive training, dietary changes and participating in competitive football contributes to aortic root enlargement."
Additional research is needed to determine ways of preventing or lessening these changes, Fonarow said.
Both studies are scheduled to be presented March 10-12 at an American College of Cardiology meeting, in Orlando, Fla. Research presented at meetings is considered preliminary because it has not been subjected to the scrutiny given to research published in medical journals.
The American Heart Association has information on heart disease.