Sitting for long periods can boost risk of pulmonary embolism

By David Liu and editing by Aimee Keenan-Greene

A new study published in the July 2011 British Medical Journal suggests women who sit for long periods of time daily,  or those who lead a sedentary lifestyle, may be two to three times more likely to develop blood clot in the lungs, compared to active women.

Previous studies show sitting in an airplane for more than 10 hours can boost risk of deep vein thrombosis in the legs, a type of venous thromboembolism.

This current study found sitting for long periods of time can boost risk of another type of venous thromboembolism known as pulmonary embolism, which can cause heart disease. 
 
For the study, Dr Christopher Kabrhel of Massachusetts General Hospital in Boston and colleagues surveyed 69,950 women in the Nurses' Health Study biennially for their lifestyle to see how a sedentary lifestyle, particularly sitting, would affect the risk of idiopathic pulmonary embolism.

During the 18-year follow-up, 268 cases were identified.  The researchers found women who spent the longest time (more than 41 hours per week) sitting were more than twice as likely to be diagnosed with idiopathic pulmonary embolism as those who sit for the least time (less than 10 hours per week).

Pulmonary embolism occurs when a blood clot travels from the leg to the lungs through the bloodstream and  blocks a lung artery triggering symptoms like difficulty breathing, chest pain, and coughing up blood.  In severe cases, patients can have blue lips and fingers because of lack of oxygen and collapse. The condition may kill the patients.  About half of the people who suffer pulmonary embolism show no symptoms.  An estimated 15 percent of all sudden deaths are caused by pulmonary embolism.