Washington, Jan 23 (PTI): Couch potatoes, beware! Sitting for long periods increases heart failure risk in men, even for those who exercise regularly, a new study has warned.

Preventing heart failure requires a two-part behavioural approach: high levels of physical activity plus low levels of sedentary time, researchers found.

The study is the first to examine the link between heart failure risk and sedentary time, said Deborah Rohm Young, lead researcher and a senior scientist at Kaiser Permanente in Pasadena, California.

"Be more active and sit less. That's the message here," Young said.

Researchers followed a racially diverse group of 84,170 men ages 45 to 69 without heart failure.

Exercise levels were calculated in METs, or metabolic equivalent of task, a measure of the body's energy use. Sedentary levels were measured in hours.

After an average of nearly eight years of follow-up, researchers found that men with low levels of physical activity were 52 per cent more likely to develop heart failure than men with high physical activity levels, even after adjusting for differences in sedentary time.

Outside of work, men who spent five or more hours a day sitting were 34 per cent more likely to develop heart failure than men who spent no more than two hours a day sitting, regardless of how much they exercised. Heart failure risk more than doubled in men who sat for at least five hours a day and got little exercise compared to men who were very physically active and sat for two hours or less a day.

Since no women were studied the results may not apply to them; results were self-reported, which could mean physical activity was over reported.  The results were based only on time outside of work and can't be applied to overall sedentary activity.

The study supports the American Heart Association recommendation that people get at least 150 minutes a week of moderate-intensity aerobic activity to reduce their risk for heart failure and other cardiovascular diseases, Young said.

The study was published in the journal Circulation: Heart Failure.