Big hearts may mean trouble in cross-country skiers

Like many other top athletes, Harald Sjoelshagen, a 66-year-old Norwegian, has an enlarged heart. When doctors noticed it in the early 1960s, he was already training hard, skiing or running almost every day. He didn't need to worry, they told him, because he showed no sign of underlying disease.

So for the next 45 years, he strapped on his Fischer cross-country skis almost every March to compete in Norway's Birkebeiner ski marathon, slightly longer than the 31 miles facing contestants on Sunday in this year's Winter Olympics.

Then in 2004, researchers studying heart health in veteran Birkebeiner skiers told Sjoelshagen he had a heart-rhythm disturbance called atrial fibrillation, which can cause fatigue and strokes.

"I feel it immediately when I have it," Sjoelshagen said. "You don't have any power at all. An old woman can pass you."

Sjoelshagen is just one example of what might amount to a larger health problem for aging sportsmen and sportswomen.

For the past few decades, case reports of endurance athletes with atrial fibrillation have trickled out of physicians' offices around the globe. Of those studied so far, the Birkebeiner data show that skiers have the highest risk.

"One man's psychological high from cross-country skiing could be another man's cardiac venom," sports cardiologist Dr. Sanjay Sharma, who was not involved in the study, told Reuters Health.

Although he calls himself an "exercise enthusiast," Sharma said extreme endurance training had become increasingly common and was likely to take a toll on the heart.

"There comes a limit in some individuals where grueling exercise just becomes too much," said Sharma, of St. George's Healthcare NHS Trust in London.

A considerable number of the 78 skiers in the Birkebeiner study, published this February in the European Journal of Cardiovascular Prevention & Rehabilitation, seem to have hit that limit: 13 of them had atrial fibrillation.

This is about what would have been expected from other studies showing that as many as 15 percent of Norwegian men older than 75 may suffer from atrial fibrillation. But the skiers, who had been followed by scientists since 1976, developed the condition at an average age of 58 - and the condition is much rarer in younger people.

Even more unexpectedly, 10 of the skiers - 13 percent - had none of the risk factors that usually go hand in hand with atrial fibrillation, such as high blood pressure, heart disease or heavy drinking. That makes it the highest rate of so-called "lone" atrial fibrillation ever reported in endurance athletes.

"We were surprised by the high incidence," said Dr. Jostein Grimsmo of The Feiring Heart Clinic in Norway, who led the research. "We knew that some cross-country skiers had developed atrial fibrillation, but we didn't know how many."