NEW YORK (Reuters Health) – Cross-country skiers who have completed more races at faster speeds are at higher risk for arrhythmias than their slower, less-seasoned peers, a new study from Sweden suggests.
Athletes who completed at least five races over ten years were 30% more likely to be diagnosed with an arrhythmia than those who only finished one race.
“It supports the notion that’s been around forever that athletes are not immune to heart disease,” said Dr. Aaron Baggish, who studies athletes’ heart health but wasn’t involved in the new research.
Still, the new findings don’t prove athletes’ extra exertion caused heart problems.
For the new study, Dr. Kasper Andersen from Uppsala University and his colleagues tracked about 53,000 cross-country skiers who completed the annual 56-mile Vasaloppet race in Sweden between 1989 and 1998.
Overall, 919 of the skiers developed an arrhythmia during the study, which ran through 2005 – including 2.7% of skiers who completed the race at least five times during the decade, vs 1.4% of those who completed one race.
What’s more, those who finished the race in the shortest amount of time were about 30% more likely to develop an arrhythmia than slower skiers.
The most common type of arrhythmia in the study was atrial fibrillation. But the researchers also found an increased risk of bradyarrhythmia with greater racing experience.
Dr. Andersen was surprised to see a higher risk of slow heart rhythms among intense athletes, because that had not been reported in past studies. “It hasn’t really been suggested before,” he told Reuters Health.
Dr. Baggish, associate director of the Cardiovascular Performance Program at the Massachusetts General Hospital Heart Center in Boston, said it’s hard to know what to do with the finding about bradyarrhythmias.
But he said the study does support what’s known about athletes and atrial fibrillation – and there are probably multiple reasons for their extra risk.
The researchers wrote June 12th in the European Heart Journal that training or competing may trigger arrhythmias as the heart adjusts to increased or decreased activity.
But both Dr. Baggish and Dr. Andersen cautioned that these findings shouldn’t keep people from playing sports.
“I think it would be a mistake for people to interpret this as a reason to avoid this type of lifestyle,” Dr. Baggish told Reuters Health. It’s still unknown, he said, whether athletes have more or fewer arrhythmias than those in the general population.
Eur Heart J 2013.