No Link Shown Between Long-Distance Flights, Blood Clots
Oct. 26, 2000 -- When John Kim travels from California to
Singapore, he knows there's a 15-hour flight ahead. So whenever he can, Kim
unbuckles his seat belt, sneaks into a space in the plane, and performs 'the
bear,' a Tai-Chi movement. Kim doesn't like sitting still for long, but there's
another purpose to his bending and moving: As a doctor, he knows exercise helps
prevent the possible formation of blood clots in his legs.
Whether people who travel long distances in a cramped space are
prone to developing clots in their legs, a disorder sometimes called
"economy class syndrome" in reference to the tight seating on
airplanes, is a matter of controversy. Although a 28-year-old British woman
recently died of a clot after a long flight from Sydney, Australia, to her home
in London, a new study in a respected British medical journal shows no
connection between extended travel and the formation of blood clots.
Kim and other doctors tell WebMD that regardless of whether the
syndrome is real, it makes sense to shed those couch-potato behaviors, even on
"We don't have much control over the plane," says Kim,
who is receiving specialized training in preventive medicine through a program
run jointly by the University of California-San Diego and San Diego State
University. "But heart disease is the No. 1 killer in the United States,
and not exercising and overeating probably account for a lot of it. I think
[clot formation] is more related to the fact that our body is designed to be
more of a hunter-gatherer and designed to move. With that in mind, I try to
move as much as possible [while flying]. Unless I am sleeping, I try to walk
and do the bear exercise."
Deep vein thrombosis, or DVT, is the medical name for blood
clots that develop in the legs. In the new study, published in the Oct. 28
issue of The Lancet, doctors at the University of Amsterdam compared the
recent travel and medical characteristics of nearly 800 people who thought they
had DVT, from 1997 to 1999. About 25% of the study group did prove to have the
disorder, but there was no evidence that those people who had travelled
recently were more likely to have the clots than those who didn't.
"These results do not lend support to the widely accepted
assumption that long traveling time is a risk factor for [DVT]," writes
study author Roderik Kraaijenhagen. "Even for journeys lasting more than
five hours, no association was apparent."
Kim tells WebMD that because this condition is relatively rare
and difficult to diagnose, a study involving 700 people may not have been large
enough to disprove a connection between blood clot formation and long