Faculty of 1000

Post-publication peer review

Spending too long on the couch

Posted by Callum Anderson on 28 February, 2010

Couch potatoes beware!, or so says Faculty of 1000 member Paul Pagel in his evaluation of a paper studying links between television viewing time and mortality in Australia.

Television is the sedentary activity of choice for many of us in the developed world. And plenty of studies have already demonstrated a relationship between televison viewing time and various disorders such as cardio-metabolic risk, diabetes and weight gain.

This particular study into television viewing habits of 8800 by Professor David Dunstan and his team is valuable due to the large sample size and also the length of time the observation ran.

By studying a large sample (8800) of adults aged more than 25 for a median period of 6.6 years, the researchers were able to get results on a big enough scale to make some powerful conclusions.

Let’s look at the numbers.

•A total of 284 deaths were reported in the period
•Of which 87 were related to cardiovascular disease

After appropriate adjustments for age, gender, exercise and and body habitus were made, the authors were able to determine that the likelihood of cardiovascular related mortality was increased for each one hour increment of television viewing per day. As viewing time passed four hours per day, the risk was significantly enlarged.

See the results for yourself

After adjustment for age, sex, waist circumference, and exercise, the hazard ratios for each 1-hour increment in television viewing time per day were 1.11 (95% confidence interval [CI], 1.03 to 1.20) for all-cause mortality, 1.18 (95% CI, 1.03 to 1.35) for CVD mortality, and 1.09 (95% CI, 0.96 to 1.23) for cancer mortality. Compared with a television viewing time of or =2 to or =4 h/d. For CVD mortality, corresponding hazard ratios were 1.19 (95% CI, 0.72 to 1.99) and 1.80 (95% CI, 1.00 to 3.25).

Dunstan and his team at Baker IDI are also careful to note in this paper that television watching itself is not necessarily the danger. Rather it is the prolonged sitting time associated with watching television. I found this paper particularly interesting because it runs against the grain, and insists that as well as promoting healthy initiatives such as exercise and lifestyle modifications, we should also be looking at methods of reducing sedentary activities. What do you think? Is it more important to encourage a healthy lifestyle or discourage an unhealthy one, or is a balance of the two necessary?


2 Responses to “Spending too long on the couch”

  1. Bob O'H said

    Damn, if it’s the being sat down that’s dangerous, I guess I shouldn’t be sat here reading this stuff.

    Blogging is bad for your health! Someone tell Susan Greenfield!

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