The world has become a sedentary place. From the prevalence of computers at the workplace to our free time spent in front of the TV or surfing the internet, as well as our profound dependence on automobiles to get just about anywhere, we simply do not move as much as we used to.

Besides the effect that a general lack of activity can have on our waistlines, a new study had determined that all that sitting may actually shorten our lifespan. This is because longevity may not simply boil down to how much physical activity we get, but may actually be independently influenced by the amount of time we spend on our rear ends.

With the increasing impact that obesity is having on our society, numerous studies have looked at the relationship between a sedentary lifestyle and the occurrence of such chronic diseases as diabetes, heart disease, and certain cancers. However, most guidelines that stem from these studies recommend more physical activity but do not give as much consideration to the independent affects of excessive time sitting down.

The current study, published in the American Journal of Epidemiology, is the first to look at the this phenomenon in relation to a person's mortality. In order to do so, researchers surveyed over 123,000 people (53,440 men and 69,776 women) who had no history of chronic disease, which included cancer, heart disease, stroke, or lung disorders. They then analyzed the amount of time these people reported sitting down or being active in relation to mortality over a 13-year period.

What they found was that an increase in leisure time spent sitting was associated with an increase in the risk of death, especially in women. In fact, women who spent more than six hours each day sitting had a 37 percent higher mortality risk than women who sat for less than three hours each day. For men, sitting for more than six hours each day was associated with an 18 percent increase in the likelihood of death when compared to men who sat for less than three hours.

These associations were strongest for cardiovascular disease versus cancer, and held true even after the data was adjusted for the level of physical activity. When low activity was factored in, the association became even stronger, with women and men who spent time sitting and were not physically active having a 94 percent and 48 percent greater risk for mortality, respectively, than the most active subjects were sat for the shortest duration.

The exact reason that sitting alone increases mortality is not known, but experts theorize that it may be linked to some of the physiological consequences that excessive sitting can have, including its effect on triglyceride levels, blood pressure, cholesterol, as well as other important markers for chronic disease.

The information may also give sedentary people impetus to get up and move around a bit more. People who spend their work day in a chair might benefit from being more active and taking a break to get up and move around. Taking the stairs and going for a walk during your break are great ways to increase blood flow, burn calories, and raise your energy level, ultimately helping you to look and feel better.

If you have questions or concerns, speak with your doctor, especially before embarking on a regimen of physical fitness.