Sedentary Lifestyle Ups Risk of Pulmonary Embolism

This study correlated the lack of physical activity with incidence of pulmonary embolism in women. It analyzed reports provided by 69,950 female nurses about their lifestyle over a period of 18 years. Medical history, physical activity, demographics, dietary patterns, smoking and other habits were taken into consideration. Inactive women were found to be twice at risk of developing pulmonary embolism than were active women. This study is the first to prove that a sedentary lifestyle doubles the risk of pulmonary embolism.

In the U.S., one to two deaths per 1,000 adults occur annually due to cardiovascular diseases associated with pulmonary embolism. Its incidence is as common as stroke or heart attack. Pulmonary embolism occurs when a blood clot from deeper veins in the lower extremities, i.e. legs, travels through the blood stream to the lungs, causing a blockage. Age, cancer, pregnancy, insufficient movement, obesity, smoking and high blood pressure are the major risk factors in the development of this disorder. It is suggested that regular exercise and activity, rather than spurts of physical exertion, cause the blood flow to improve and reduce the risk of pulmonary embolism.

* The study involved nurses, aged 30 to 55 years, who answered a baseline questionnaire in 1976 following which, biennial questionnaires were used to analyze their lifestyle, daily activities, and disease risks for 18 years.
* The time they spent sitting or exercising was recorded in terms of hours per week. Detailed data on their physical activities was obtained using a physical activity questionnaire.
* Relationship between physical activity and occurrence of pulmonary embolism was analyzed.
* With the help of medical diagnosis reports, 268 cases of pulmonary embolism were identified. Data on age, parity, race, BMI, total energy intake, menopausal status, coronary heart disease, rheumatological disease, hypertension, use of multivitamins, warfarin and non-aspirin non-steroidal anti-inflammatory drugs, dietary pattern and physical activity were correlated with the incidence of pulmonary embolism.

* Women with more physical inactivity, who spent more time sitting at home for more than 40 hours a week tended to have higher BMIs and higher energy intake. They were at the highest risk of developing pulmonary embolism.
* Statistical adjustments were made for factors that would lead to false interpretations (confounders), such as medication, menopause, race, age, etc.
* Inactive women were more than twice at risk of pulmonary embolism than were the most active women.
* A strong correlation was found between physical inactivity, obesity, hypertension, coronary heart disease and pulmonary embolism.

Shortcomings / Next steps
More than 95 percent of the women in this study were white and aged above 55 years. The results, therefore, cannot be generalized to other ethnicities, races, ages and men. Furthermore, the participants were nurses who had access to medical help and were well educated. This further limits the generalizability of this study.

Physical movement of legs helps blood flow in veins. Lack of motion slows down the circulation and return of venous blood to the lungs, thus increasing chances of blockage in veins. This may be further aggravated by low levels of certain substances in blood, thereby increasing blood viscosity. Physical inactivity increases the chances of blockage in blood vessels by the formation of clots, increasing the chances of fatal cardiovascular diseases. The study recommends regular physical exercise and implies that the adverse effects of inactivity can be reversed by taking up physical activity. The authors suggest public health campaigns to educate the general population about the risks associated with physical inactivity. The incidence of pulmonary embolism could thus be reduced.

For More Information:
Physical Inactivity and Idiopathic Pulmonary Embolism in Women: Prospective Study
Publication Journal: British Medical Journal, 2011
By Christopher Kabrhel; RaphaëlleVarraso; Massachusetts General Hospital, Boston; Harvard Medical School, Boston, Massachusetts; Centre for Research in Epidemiology and Population Health, Villejuif, France and Université Paris Sud, Villejuif, France

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