Writers take note: get up, or die.

"People who sit for the majority of their day have much higher mortality rates than people who don't, even if they're physically active during another part of the day," says Peter Katzmarzyk, an epidemiologist.

"We've known for a while that people who watch a lot of television are more likely to be obese and have the metabolic syndrome," he notes. (The metabolic syndrome, which increases the risk of heart disease and diabetes.)

"We've now shown for the first time that sitting is directly related to mortality.

Long periods of sitting cannot be compensated for with occasional leisure time physical activity. If you're active for just 30 minutes a day, how is that supposed to wipe out all the other hours of sitting?

Muscles seem to be extremely inactive while sitting, and this may change the way they metabolize compounds and may effect the regulation of insulin and glucose. Just getting people to stand up changes the physiology in their limbs."

Advice: "Stand up. Walk around, do anything like that to encourage blood flow and increase the muscle activity in the lower limbs."

Source: CSPINET (Canada)