People who sit for hours on desks or watch television need to exercise for more than 30 minutes a day to avoid health risks, according to an Australian study released today.
The study, conducted by the University of Sydney, found that people who sit more than six hours a day without exercise have a higher risk of dying from cardiovascular disease than those who exercise for an hour a day.
The study, published today in the Journal of the American College of Cardiology, included a sample of 150,000 people over the age of 45, which lasted nine years.
A normal Australian worker spends more than six hours a day sitting, which researchers classify as "sitting for long periods".
High sitting time was associated with health problems including cancer, obesity, heart disease, diabetes and even depression.
It turns out that standing reduces the risk of cardiovascular disease for those who sit four hours a day or less, but it has limited effect for those who sit longer.
Those who sit for long periods of time and exercise for 20 to 40 minutes a day, such as walking or climbing stairs, have a significantly lower health risk, the study showed.
"In our study, sitting time was consistent with early death and cardiovascular mortality in less physically active groups," said Professor Emmanuel Stamatakis, lead author of the study.
For example, people who were physically inactive and sat for more than eight hours a day were 107 percent more likely to die of cardiovascular disease than those who had been physically active for at least one hour a day and sat for less than four hours.
"Any movement is good for health," Stamatakis said, noting that intensive physical activity is the most effective.