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Full response from lead author of study exploring link between TV-viewing and death from inflammatory causes

Below is the full response from lead author, Megan Grace, of the study Television Viewing Time and Inflammatory-Related Mortality, published in the journal Medicine and Science in Sport and Exercise in October, 2017. This study was the subject of a Research Check that explored whether media reports on the paper, claiming binge-watching TV increases your risk for Alzheimer’s disease and diabetes, were accurate.

The author was asked whether media reports on the study were fair and balanced, and whether she saw any shortcomings.

The field of sedentary behaviour is still developing, with some large population studies showing links with poor health and mortality outcomes, whereas others do not. This naturally leads to some controversy in the field, and scientists will of course critique the study and point out its limitations. This is reflected in recent media coverage, and is all part of a healthy dialogue between scientists.

A major concern in this area is to try and avoid creating confusion for the general public. We acknowledge that diet and exercise are both important means by which people can improve their health. However, there is some scientific uncertainty about whether the health effects of TV viewing differ from sitting in general.

Some suggest that the effects of TV on health outcomes are at least partly mediated by unhealthy eating (snacking), but the evidence that this completely accounts for the detrimental effects of TV viewing on health are not convincing. Other scientists suggest that the effects seen for TV in large population studies are stronger because it is easier for people to recall their TV viewing time more accurately than overall sitting.

It is also important not to ignore the results from experimental studies, which have demonstrated biological plausibility for a negative impact of prolonged periods of sitting on many health parameters, including effects on blood sugar and fats, blood pressure, and blood vessel function. Importantly, these effects are apparent even if everything else is equal (including food intake), and time spent sitting is the one factor that is changed.

In regards to participation in moderate-to-vigorous physical activity offsetting the negative impacts of prolonged sitting, the amount of this type of activity that is required to do this is reported to be well above the current recommendations – in the order of 60 minutes or more per day. Considering one of the most commonly reported barriers to participation in exercise is a lack of time, this may not be feasible for many people.

The results of our study, and others in the area, need to be considered in context. Researchers in this field are building a convincing argument that prolonged sitting is bad for health, and that simple, practical, short periods of activity throughout the day may help to reduce the long-term risk of disease and premature death. What we recommend is consistent with the Australian Physical Activity & Sedentary Behaviour Guidelines: “Make your Move – Sit less – Be active for life!” Both exercise and avoid periods of prolonged sitting throughout the whole day (at home, while watching television, and at work). - Megan Grace, Research Fellow, Baker Heart and Diabetes Institute

The Conversation has asked Megan for references to the studies she refers to.

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