Exercisers at risk from too much TV

22 January 2010: More time spent sitting in front of the television leads to an increased risk of dying even if you exercise, according to research.

Television watching is the most common, inactive leisure pursuit in many developed countries. Although the health benefits of regular exercise are well recognised, less is known about the possible harmful effects of too much sitting.

Previous studies have shown that increased time spent watching television is associated with an increased risk of weight gain and certain diseases, including some cancers and diabetes. This study, carried out in Australia, looked specifically at the length of time people spent sitting watching television and their risk of dying from particular causes.

The researchers followed nearly 9,000 people for six years. Those taking part were asked to record how long they spent sitting watching television over a week.

The results showed that there was an increase in the risk of dying from all causes, in particular from cardiovascular disease, with each extra hour spent watching television. This was despite taking into account factors that are known to increase the risk of dying from cardiovascular disease, such as smoking. The researchers also found that this increased risk stayed the same no matter how much exercise people did.

The findings suggest that being inactive for too long, as distinct from not spending long enough doing physical activity, can have a harmful effect on health. The researchers admit that people who spend more time watching television are likely to have poorer health because they use up less energy and eat more – increased snacking is associated with more time spent watching television. However, this was accounted for when the results were calculated, so it is probable that something else is involved.

The researchers suggest that being sedentary may raise levels of glucose and cholesterol in the blood, both of which are causes of cardiovascular disease. However, the study does not investigate this and so it is not possible to say the cause of the increased risk of cardiovascular disease is sitting for long periods of time.

The researchers looked only at time spent sitting watching television. This was because although there are other sedentary household behaviours, television watching is the one that accounts for the most time in countries such as the US, Australia and the UK. However, as the study found no link between risk factors for cardiovascular disease specifically associated with television watching, it is possible that it is not the television watching but rather the act of sitting for long periods of time that increases a person’s risk. It is also important to note that the researchers took only one measurement of how long people spent watching television. This was recorded at the beginning of the study and could have changed over the course of the six years.

Bupa International’s medical director, Dr Sneh Khemka, said: “This study suggests that sitting for too long may be harmful. Further research to confirm this would be interesting but the upshot is the same: the more time people spend moving about, the less they have to sit around watching television, and this can go a long way towards improving their health.

“We already know very well that not doing enough physical activity increases the risk not only of cardiovascular disease, but also a host of other serious health conditions. If the very act of just sitting for too long may add to this, it should only serve as further incentive for people to take regular exercise.”

Key facts

The term cardiovascular disease covers a number of conditions that affect the heart and blood vessels. These include stroke, coronary heart disease and deep vein thrombosis.
Coronary heart disease leads to an increase in the build-up of fatty deposits in your arteries. This puts more strain on your heart because it is harder to pump blood around the body.
Worldwide, more people die each year from cardiovascular disease than any other cause.
As well as taking regular exercise, you can reduce your risk of developing cardiovascular disease by not smoking, not drinking alcohol excessively and reducing the amounts of salt and fat in your diet.