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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?)

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  • Since the effects of a sedentary lifestyle are long term, how can you realistically do any human studies that aren't observational?
    – jamesqf
    Jul 1 '17 at 18:28
  • I understand that but in that case what are the chances all these studies show definite relationship? Are there studies that ruled out poor eating habits?
    – Democrat
    Jul 2 '17 at 5:37
  • Any reasonable study would try to control for extraneous factors, such as eating habits.
    – jamesqf
    Jul 2 '17 at 17:50
  • 3
    @jwenting: Outside of formal logic, nothing "makes" causation with certainty. Gettin' real tired of people dropping this turd as if it were genuine insight.
    – rob
    Jul 3 '17 at 20:34
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    @jwenting, that is the exact opposite of what I wrote. Causation can not be definitively proven, therefore you have to accept correlation as evidence in support of a hypothesis. If you want to dispute the significance of a correlation or propose and unconsidered confounder, do it. "Correlation does not make causation" is a truism, and utterly unhelpful.
    – rob
    Jul 4 '17 at 6:36
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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.

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  • I have seen second source and since it states there's no definitive causal link yet it doesn't answer my question. What is is the name of study found on University of Delaware website? It asks for credentials to authorize.
    – Democrat
    Jul 6 '17 at 17:18
  • @Democrat I apologize, I fixed the links. They should take you directly to the journal websites now. I see now that your question may be more related to causal proof vs. correlation studies. As far as that is concerned, however, I think I would have to return the question to you, and ask you to clarify; what would a causal study proving this relationship look like?
    – Microscone
    Jul 6 '17 at 17:29

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