Air travel may be linked to blood clots

Does flying make marathon runners more susceptible to blood clots? A new study shows there may be a link between the two.

According to Reuters Health, the study, done by researchers at the Hartford Hospital in Connecticut, has found that marathon runners who fly to races could end up with higher levels of the blood molecules that have been linked to blood clots.

Does that mean flying to a race will always cause blood clots? Probably not, say the researchers, but it could explain the rare incidences of otherwise healthy marathoners experiencing clots after a race.

“It seems that the two activities could have a compounding effect when they are carried out back-to-back,” Beth Parker at Hartford Hospital in Connecticut, told Reuters.

As part of the study, Parker and her colleagues took blood samples from 41 healthy non-smokers who participated in the 2010 Boston Marathon. Of those 41, 23 had to fly more than four hours to get to the race. The researchers collected blood three times: after they landed in Boston, immediately after the race, and when the participants were back home.

Six of the 23 who traveled by air to the race had elevated levels of a substance called D-dimer, which has been used as a sign of possible blood clots, but none of the 18 runners who lived close to Boston did.

But don’t let that stop you from heading to a destination race just yet. Parker told Reuters that while flying could contribute to a slightly increased risk of blood clots, the benefits of endurance running far outweigh the small risks for most people.

The study was published in the American Journal of Cardiology.