WEDNESDAY, Jan. 12 (HealthDay News) -- If you sit all day at an office and worry about its effect on your weight and health, take a few breaks.

That's the advice from a new study that finds that people who sit for extended periods of time without taking short breaks are at higher risk for heart disease than those who take more frequent timeouts to stand up and walk around.

The cardiovascular risk that stems from remaining sedentary for prolonged periods of time (at the office, for example) manifests itself in the form of larger waists, higher blood pressure, higher levels of triglycerides, increased body inflammation and lower levels of "good" cholesterol, the authors noted.

What's more, the negative impact of such lengthy bouts of inactivity seems to apply even to those who routinely go to the gym.

"These findings are not surprising," said Dr. Murray A. Mittleman, director of the cardiovascular epidemiology research unit at Beth Israel Deaconess Medical Center and an associate professor in the department of epidemiology at the Harvard School of Public Health in Boston.

"In fact, the Surgeon General report recommends that individuals should accumulate activity incrementally throughout the day," noted Mittleman, who was not a member of the Australian research team. "And this is really consistent with that."

The team, led by Genevieve N. Healy, of the Cancer Prevention Research Centre at in the School of Population Health at the University of Queensland in Herston, Australia, report their findings in the Jan. 12 online edition of the European Heart Journal.

"Even if you exercise for 30 to 60 minutes a day, what you do for the rest of the day may also be important for your cardiovascular health," Healy explained. "This research suggests that even small changes to a person's activity levels [as little as standing up regularly] might help to lower cardiovascular risk. These changes can be readily incorporated into the person's day-to-day life [including the work environment]. Stand up, move more, more often, could be used as a slogan to help get this message across."

The authors pointed out that in developed countries people spend more than half of their day sitting, on average. At the same time, they point out that heart disease is the number cause of premature death in both the United States and Europe.

To explore the potential connection between the two, Healy and her colleagues crunched numbers taken from the U.S. National Health and Nutrition Examination Survey. The data involved about 4,800 American men and women aged 20 and up who participated in the survey between 2003 and 2006.

All those surveyed had been outfitted with a accelerometer on their hip, to monitor a week's worth of walking, running and sitting routines. In addition, the authors looked at measurements concerning a number of heart disease-related risk factors, including waist circumference, blood pressure and cholesterol levels.

At the extremes, the most sedentary participants were found to sit a little more than 21 hours per day, while the least sedentary sat just under two hours per day. The fewest activity breaks taken over the course of a full week amounted to less than 100, while the most weekly breaks registered at nearly 1,300.

The team found that, for white participants, the longer they spent being sedentary the larger their waist circumference. Racial differences did seem to play a role, as Mexican-Americans didn't seem to be impacted by this association while blacks actually demonstrated the opposite dynamic.

Blood fat (triglyceride) levels were also found to be significantly higher among the most sedentary, as were signs of insulin resistance, often a precursor to diabetes.

Overall, those who took the most breaks from sitting (even if they spent a great deal of time being sedentary) were found to have the smallest waists: participants among the top quarter of break frequency had a 1.6-inch smaller waist than those in the bottom quarter.

Taking more breaks was also linked to lower levels of C-reactive protein, a marker for problematic inflammation.

The bottom line, according to the researchers: people should be encouraged to take activity breaks.

For example, they suggested that while at work employees consider standing while on the phone or in a meeting, choosing to walk over to colleagues rather than e-mailing or calling them, and using the stairs to access their work area and/or bathrooms.

"I think the recommendations they make for activity breaks all make sense," Mittleman said. "We always advise people to take a walk during their lunch break, for example. And if they can't go outside then walking up and down the corridors works just as well. The point is that for most people basically any kind of activity helps."

Susan Finn, chairwoman of the American Council for Fitness & Nutrition, said that the research team's take on the exercise issue "makes great sense."

"The point here is that setting up huge goals for people to get them to devote huge blocks of time during the day to exercise just doesn't work," she suggested. "People won't do it. Instead, getting people to engage in purposeful activity, trying to motivate small changes, is the way to go."

"And I think we've seen the sense of this over and over again," Finn said, "whether we're talking about reducing fat, reducing sodium or reducing sitting and taking the stairs. It's all about making this stuff, these small changes, doable for people, and the workplace is a very good example, a very good place to start."

More information

For more on physical activity, visit the National Center for Chronic Disease Prevention a...Health Promotion.