Does a sedentary lifestyle cause health concerns?

Question

There're number of articles that suggest sedentary lifestyle is dangerous for health some of which go as far as saying it's as bad as smoking.

According to an article on John Hopkins Medicine:

Lack of physical activity has clearly been shown to be a risk factor for cardiovascular disease and other conditions:

Less active and less fit people have a greater risk of developing high blood pressure.

Physical activity can reduce your risk for type 2 diabetes.

Studies show that physically active people are less likely to develop coronary heart disease than those who are inactive. This is even after researchers accounted for smoking, alcohol use, and diet.

Lack of physical activity can add to feelings of anxiety and depression.

Physical inactivity may increase the risk of certain cancers.

But many studies I've encountered are just observational studies that show correlation for low physical activities like watching TV.

Are there any studies that directly establish causal link between these conditions and sedentary lifestyle? (And not, for example, simply having obesity as a confounding factor?)

Answer 1

This, like many other questions on this board, is an expansive topic, with thousands of peer-reviewed publications on the topic.

I suggest reviewing a few review articles, found here and here (there are many, many more, but these are a good starting point)

A couple of key findings from the second source above:

1. Based on inconsistency in findings among the studies and lack of high-quality prospective studies, insufficient evidence was concluded for body weight–related measures, CVD risk, and endometrial cancer.
2. Moderate evidence for a positive relationship between the time spent sitting and the risk for type 2 diabetes was concluded.
3. Based on three high-quality studies, there was no evidence for a relationship between sedentary behavior and mortality from cancer, but strong evidence for all-cause and CVD mortality.

Most review studies you will find will conclude that more studies with rigorous methodology need to be undertaken.

My own personal take-away on this issue is this: Many studies confound time spent sitting with lack of physical exercise. These are two different behaviors (for instance, I spend most of my work day sitting in a chair. However, I exercise vigorously at least 4 times a week, for 45 minutes or longer. Different studies would treat this behavior differently). In general, however, more time sitting leads to negative health outcomes, and more time exercising leads to more positive health outcomes.