The body of research that associates prolonged sitting with all cause mortality, heart disease and several types of cancer continues to grow. A news story published last month in a WebMD newsletter listed three recent studies that support those previously published.
The studies can control for other factors, including how much exercise a person gets or what their BMI (fat status) is and look only at the effect of prolonged sitting. The findings are that sitting for more than an hour at a time has significant adverse consequences.
The health promotion message is being modified accordingly. It now goes beyond telling people to get daily exercise and advises them to limit sitting as well. (you realize 'people' and 'them' is you, right?)
I have read at least one of the studies that was mentioned in the article and I am in the process of reading another, but here are some of the findings that you might find interesting:
A study by Owen associates sitting with an increase in inflammation and other physiological changes that have been linked to cancer occurance.
Friedenreich reports that exercise can prevent colon and breast cancer. She looked at both colon and breast cancer incidence and compared people who exercised the most to those that exercised the least or not at all and found between 20 and 30% fewer cancer cases in the exercisers.
Patel and Berstein (the study I am reading now) have found a link between sitting, regardless of weight and exercise levels, with any cause of death in the 14 years that they followed a group of persons. Results included that for men who sit more than 6 hours continuously, there is a 18% greater risk of death than for men who sit the least and for women the increased risk was 37%.
A study that I reported on earlier this year (here), found that sitting time increased the risk of heart disease.
The WebMD article ends with the suggestion that everyone make time for exercising but also include break times in their sitting occasions. I have to be honest with you, and you can verify this with my classmates and even my mother (though I see her less often) - I have read so many of these studies that I have become almost incapable of sitting for more than an hour for fear that it will kill me :)