Marathon running has been found to trigger a dangerous condition that leads to the buildup of fluids in the lungs.
The study, presented at a meeting of the European Respiratory Society in Vienna, showed competitors in the long-distance races are more prone to the condition – known as pulmonary oedema – which causes breathlessness, severe cough, and even heart attacks or respiratory failure in serious cases.
For the study, researchers from the United States and Italy analyzed 26 runners who completed the 2011 Steamtown Marathon in the U.S. They took chest radiographs of the runners the day before the race and then 19, 56 and 98 minutes after the race. By tracking the runners at different times, they ensure that any increase in blood volume would return to normal, and assess the level of oedema.
The results showed about half the runners had some level of pulmonary oedema about 20 minutes after the race; one in five of them had moderate to severe symptoms. The condition was still present one hour after the marathon was completed.
Researchers also found women were at much higher risk than men.
"Marathon running is linked to an increased risk of pulmonary oedema, and it seems that women are at higher risk than men regardless of marathon finishing time,” said lead researcher Dr. Gerald Zavorsky from the Marywood University. “While pulmonary oedema can be a negative consequence of marathon running, regular exercise can also keep you fit and healthy. We do not yet know the impact of this finding on long-term health of runners."