WSFA/NBC - Heart disease is the number one killer in the United States, according to the American Heart Association.
Staying healthy can improve your heart health, but doctors have discovered that too much exercise can actually lead to heart disease, even death.
Their findings applied to one specific group of people: white men.
"More is not always better," said Dr. Danny Le.
Le at Medical City Arlington reviewed a recent study out of Chicago that found white men who work out at least seven and a half hours a week were twice as likely to suffer from heart disease than people who worked out a moderate amount.
Vigorous exercise can stress the arteries and lead to plaque build-up but the correlation did not exist for white women or black men and the researchers don't know why.
Le said, "There might be some biological differences among the sex and the race that we have yet to determine."
More research is needed to find out why very active white me are 86 percent more likely to experience a plaque build-up in their arteries by middle age.
However, Dr. Le says the findings don't mean stop working out.
"Multiple studies have determined that people that are more active and exercise live longer and they decrease the mortality."
The American Heart Association recommends two and a half hours of moderate exercise a week for better heart health.