In order to be an Olympian, athletes typically work very hard to get their bodies in peak shape. And yet, a new study says that intense physical training may have an unintended consequence — chronic asthma.

Conducted by the University of Western Australia, the study analyzed athletes from the Olympic Games from 2000 to 2010 and found that roughly eight percent have the condition.

Researchers say that air quality has an obvious impact on asthma, but this doesn’t account for the large number of athletes who suffer from the disease.

“Inhaling polluted or cold air is considered an important factor which might explain the cause in some sports, but not in all,” said study researcher Kenneth Fitch.

Since the disease was found to be most common in endurance athletes, researchers think that long years of grueling training may be a cause.

Still, Fitch pointed out, asthma and narrowed airways aren’t necessarily an impediment to performing well in sports.

[NBC News]