You thought it was OK to watch as much TV and do as much computer as you like as long as you engaged in plenty of exercise. Wrong!
We are all familiar now with the positive benefits of exercise and the continual urgings for us to do lots of it. However, there have been some interesting recent studies that have suggested that too much sedentary behaviour like watching TV, independently of how much exercise you do can harm you!
Sedentary behaviour is excessive sitting. Examples of this are watching TV and playing or working on the computer. It can take up to 55% of the waking day in some cases.
Television viewing time in particular has been reported as the most widespread leisure-time sedentary behaviour of adults.
Scientific evidence is accumulating for adverse associations between TV time and several health risks including heart disease, stroke, metabolic syndrome (diabetes and obesity) and some cancers. These associations were independent of physical activity and the bad effects of elevated TV time has actually been observed in physically active people.
A study published in 2011 in the International Journal of Epidemiology found that for every extra hour of TV watching per day, there was an increased risk of all causes of mortality by 4% and of heart problems of 7%. They followed 13,197 men and women over a period of around 9.5 years. Cancer statistics in the group were not affected. The results were independent of smoking, alcohol intake, medications, history of heart problems, diabetes, cancer or body mass index. These findings were independent of how much exercise was done.
In another study presented in June 2011, the results of the National Institutes of health – AARP Diet and Health study results were presented. They followed 240,819 adults age 50-71 who were free of cancer, heart disease or lung diseases. They were followed for 8.5 years. When they compared people who watched less than an hour of TV per day to those watching 7 or more hours per day, they found that the higher TV viewing group had a significantly increased of mortality of 61%. The higher viewing group also had an 85% increased risk of heart disease or stroke, and a 22% increased risk of cancer.
The researchers found that even when adults reported 4-7 hours a week of moderate to vigorous activity but had 5-6 hours of TV watching per day, they had a 50% increased risk of all causes of mortality. These adults had a doubled risk of heart and stroke mortality. All These results ware in comparison with the lowest TV watching group of less than one hour per day.
In the most recent study published January 2012 in the European Heart Journal, the researchers stated that inactivity is a “universal risk factor’ and that ownership of a TV and car seem to increase the risk of a heart attack. They looked at 29,000 people over 52 countries in Asia, Europe, the Middle East, Africa, Australia and North and South America and called it the INTERHEART study. They found that mild to moderate physical activity at work and any physical activity during leisure time reduces heart attack risk independent of any other risk factors. These findings applied to most regions of the world and in countries with low, middle or high income levels.
If adults undertook very vigorous activity there was no benefit, and the researchers don’t have a reason for it yet. I would speculate that extremely vigorous activity could place excessive stress on the body.
I think it is clear from these studies that the message is that regular physical exercise will not protect you if you lie about too much watching TV or spend time on the computer. Whether it be at work or at home, you need to remain active.
Katrien Wijndaele et al. Television Viewing Time Independently Predicts All-cause and Cardiovascular Mortality. International Journal of Epidemiology. 2011;40(1):150-159. © 2011 Oxford University Press
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