Science-- there's something for everyone

Monday, August 2, 2010

Sitting can kill you

It’s well known that a lack of exercise and obesity can increase one’s fatality risk. However, a study by Alpa Patel and his colleagues from the American Cancer Society has shown that the amount of time spent sitting, independent of physical activity, correlates strongly with risk of death.

The researchers examined data from 120,000 men and women with no prior history of cancer, heart attack, stroke, or emphysema/other lung disease. The volunteers had all been enrolled in a 1992 cancer prevention study designed by the American Cancer Society. Participants were followed over the next 14 years, during which time there were about 19,000 deaths. Participants had been asked not only about diet and exercise, but also about the amount of time they spent sitting each day.

Regardless of other factors, the time spent sitting correlated strongly with increased death risk, particularly from cardiovascular disease. Men who sat for more than six hours per day were 18% more likely to die than men who sat for less than three hours per day. Men who combined sitting for over six hours per with a lack of exercise throughout the day were 48% more likely to die. For women, the numbers were 37% and 94%!

I feel I should say a couple of things about these numbers. First, correlation is not causation. Does sitting cause metabolic changes that lead to heart disease, or does a predisposition to heart disease lead one to prefer to sit? Second, although those numbers are scary, remember these are percentage increases. Only about 15% of all the participants died during the entire fourteen year study.

Still, as I sit here writing this, I’m thinking now might be a good time to get up and walk the dog.