SUNDAY, Nov. 12, 2017 (HealthDay News) -- If you love to while away a weekend watching a season's worth of episodes from a favorite TV series, you may inadvertently put yourself at risk for developing a dangerous blood clot.
When researchers compared people who reported watching TV more often to those who seldom or never watched TV, the risk of a venous thromboembolism (VTE) jumped by 70 percent.
A VTE is a type of blood clot that can block blood flow in a vein, according to the American Heart Association.
"I don't think TV watching itself is an evil thing, but everything in moderation," said study co-author Dr. Mary Cushman. She's a professor of medicine at the University of Vermont's Larner Medical College.
"Think about how you're spending your time, and see if you can take advantage of your TV time to get some activity in," advised Cushman.
Her own solution? Walking on her treadmill when she watches TV.
Cardiologist Dr. James Catanese concurred. He said when he watches TV, he rides a stationary bike.
If you're not going to exercise while watching TV, he recommended watching an episode and then doing something physical for 20 minutes.
"Physical inactivity is a risk factor for every cardiovascular disease, including VTEs," said Catanese, chief of cardiology at Northern Westchester Hospital in Mount Kisco, N.Y. He wasn't involved in the research.
The study included more than 15,000 U.S. adults. They were between 45 and 64 years old when the study began between 1987 and 1989.
The study volunteers were asked if they watched TV "never or seldom, sometimes, often or very often." TV viewing information was updated in two time periods: 1993-1995 and 2009-2011, the researchers said. The study didn't gather information on how many minutes a day people watched TV.
During more than 20 years of follow-up, nearly 700 people developed the dangerous blood clots.
Even people who regularly exercised and met the U.S. government's weekly exercise recommendations -- 150 minutes of moderate or 75 minutes of vigorous exercise a week -- still had an increased risk of VTE. The risk of the blood clot was even higher -- 80 percent -- for those who were regular exercisers who watched TV "very often" compared to those who "never or seldom" watched.
The study wasn't designed to prove a cause- and-effect relationship, and other factors may have contributed to the development of VTE. For example, Cushman said, obesity is a known risk factor for developing blood clots.
When they adjusted the data to control for weight, they found that obesity explained about 25 percent of the risk. However, lack of movement was still found to increase the risk of VTE by 50 percent.
Cushman also pointed out that a combination of risk factors can make the odds of developing a VTE even worse. People who had the highest obesity status and watched TV very often had about 2.4 times the risk, she said.
Along with using TV time to exercise, Cushman also recommended taking advantage of digital video recorders, offered by most cable TV providers. These devices allow you to fast-forward through commercials and spend less time watching TV.
Or, she said, take a walk before you sit down to watch TV. "You've got to pay to play," she said, adding that it's helpful to train yourself to think that way.
Other ways to prevent clots include maintaining a healthy weight, getting regular physical activity and eating a heart-healthy diet, Cushman said.
The study is to be presented Sunday at the American Heart Association's annual meeting, in Anaheim, Calif. Findings presented at meetings are generally viewed as preliminary until they've been published in a peer-reviewed journal.
Learn more about blood clots from the American Heart Association.