The study, led by Kansas State University researcher Richard Rosenkranz, was carried out on a sample of 63,048 Australian men aged 45-65.
The men were asked to report the number of hours they spent sitting down, as well as whether they had any chronic diseases.
They were put into groups according to their daily sitting time, of either: less than four hours, four to six hours, six to eight hours, or more than eight hours.
Men who sat for more than four hours a day were at a significantly increased risk of developing chronic disease compared to those who sat for less than four hours. The prevalence of chronic diseases climbed up as the number of hours the participants spent sat down increased. Those who sat for more than six hours a day were at a particularly high risk of diabetes.
Office workers at heightened riskThis finding is especially relevant to office workers, who spend the majority of their day sat at their desk.
According to Rosenkranz:
"We know that with very high confidence that more physically active people do better with regard to chronic disease compared with less physically active people, but we should also be looking at reducing sitting. A lot of office jobs that require long periods of sitting may be hazardous to your health because of inactivity and the low levels of energy expenditure."
In addition, the authors explained that the findings were still consistent among participants of a similar body mass index, income, age, and physical activity level - with those sitting for longer reporting more chronic diseases.
"It's not just that people aren't getting enough physical activity, but it's that they're also sitting too much. And on top of that, the more you sit, the less time you have for physical activity."
Chicken or Egg?The investigators explained that they are not sure whether the amount of sitting time was responsible for the development of chronic disease, or if those with chronic diseases were more likely to sit for longer hours.
Sedentary office workers may have a higher risk of developing chronic diseases
Rosenkranz concluded: "It's a classic case of, 'Which came first: the chicken or the egg?"
However, there is also significant research to suggest that prolonged sitting can indeed increase one's risk of certain diseases.
Consistent with the findings of this study, a previous investigation published in Diabetologia, which pooled the results of 18 studies involving nearly 800,000 participants, similarly identified that people who sit around for long periods are at a heightened risk of developing type 2 diabetes, heart disease and premature death, regardless of their physical activity.