Watch how long you sit!

I recently blogged about the relationship between lack of sleep and disease. Now it looks like a group of investigators in Canada has found some evidence linking sitting time and various chronic diseases. The paper was published recently in the Medicine and Science in Sports and Exercise journal.

Katzmarzyk and his co-workers from the Pennington Biomedical Research Centre in Ontario noted that although moderate-to-vigorous physical activity is related to premature death, the relationship between sedentary behaviors and mortality has not been fully explored and may represent a different paradigm than that associated with lack of exercise. They prospectively examined sitting time and mortality in a representative sample of 17,013 Canadians 18-90 yr of age. Information such as the daily sitting time (almost none of the time, one fourth of the time, half of the time, three fourths of the time, almost all of the time), leisure time physical activity, smoking status, and alcohol consumption were captured at commencement of the study.

The volunteers were then followed prospectively for an average of 12.0 yr. Of the 17.013 volunteers, there were 1832 deaths (759 of cardiovascular disease (CVD) and 547 of cancer). After adjustment for potential confounders, there was a progressively higher risk of mortality across higher levels of sitting time from all causes and CVD but not cancer. Similar results were obtained when stratified by sex, age, smoking status, and body mass index.

Katzmarzyk and his co-workers concluded from their study that their data demonstrate a dose-response association between sitting time and mortality from all causes and CVD, independent of leisure time physical activity. In addition to the promotion of moderate-to-vigorous physical activity and a healthy weight, physicians should discourage sitting for extended periods.