Sitting for long periods ups blood clot risk

A study has found that women who sit for long periods everyday are two to three times more likely to develop a life-threatening blood clot in their lungs than more active women.

The study is the first to prove that a sedentary lifestyle increases your risk of developing a pulmonary embolism - a common cause of heart disease.

An editorial published alongside the study said that, although the risk is small - equivalent to seven extra cases per 10,000 person years, and only slightly higher than seen in users of oral contraceptives or long haul airplane travel - the findings could have major health ramifications.

Pulmonary embolism develops when part, or all, of the blood clot travels through the bloodstream from the deep veins in the leg and up into the lungs. Symptoms include difficulty breathing, chest pain and coughing.

Dr Christopher Kabrhel and colleagues studied 69,950 female nurses over an 18-year period providing detailed information about their lifestyle habits by completing biennial questionnaires.


They found that the risk of pulmonary embolism is more than two times higher in women who spend most time sitting (more than 41 hours a week outside of work) compared with those who spend least time sitting (less than 10 hours a week outside of work).

In the accompanying editorial, researchers in Canada said that the study "reinforces the notion that prolonged inactivity increases the risk of venous thromboembolism, and it shows how this occurs in everyday life."

The study has been published in bmj.