A study, led by researchers at Columbia University in the United States, found that leisure-time sitting while watching TV was associated with a greater risk of heart disease and death.
The research, published in the Journal of the American Heart Association, also found that moderate-to-vigorous exercise may reduce or eliminate the harmful effects of sedentary television watching.
For the study, the researchers followed 3,592 people for almost 8.5 years.
The participants who had logged the most TV-viewing hours around four or more hours a day had a 50 per cent greater risk of cardiovascular events and death compared to those who watched the least amount of TV for less than two hours a day.
Even for the most dedicated TV watchers, moderate to vigorous physical activity, such as walking briskly or doing aerobic exercise, reduced the risk of heart attacks, stroke, or death.
According to the study, no increased risk of heart attack, stroke or death was seen in people who watched TV for four or more hours a day and engaged in 150 minutes or more of exercise a week.