The study further warns that a daily session at the gym won't undo the damage because any increase in fitness from an hour's exercise is overridden by several hours of sitting.
Scientists from the Medical College of Wisconsin tracked levels of activity of 2,031 adults whose average age was 50.
They compared the number of hours each participant spent sitting down each day with the levels of deposits in blood vessels that act as signal for heart disease.
The participants all spent between two to 12 hours a day sitting at the office and in front of the television. The researchers concluded that for every hour spent sitting, the levels of deposit rose by 14 per cent.
Regular running, gym sessions and aerobics classes showed no evidence of significantly mitigating the risk.
Lead researcher Dr Jacquelyn Kulkinski, an assistant professor of cardiovascular medicine, said that adults with office jobs should go for a walk every hour: "Reducing the amount of time you sit by even an hour or two a day could have a significant and positive impact on your future cardiovascular health.
(Source: The Independent)