New research is helping medical experts devise formulas for how long a typical office worker should spend sitting and standing.

Studies have found that sedentary behavior, including sitting for extended periods, increases the risk for developing dozens of chronic conditions, from cancer and diabetes to cardiovascular disease and nonalcoholic fatty liver disease. Some ergonomics experts warn that too much standing also can have negative effects on health, including a greater risk for varicose veins, back and foot problems, and carotid artery disease.

“The key is breaking up your activity throughout the day,” said Alan Hedge, a professor of ergonomics at Cornell University. “Sitting all day and standing all day are both bad for you,” he said.

For every half-hour working in an office, people should sit for 20 minutes, stand for eight minutes and then move around and stretch for two minutes, Dr. Hedge recommends, based on a review of studies that he has presented at corporate seminars and expects to publish. He says standing for more than 10 minutes tends to cause people to lean, which can lead to back problems and other musculoskeletal issues.

The British Journal of Sports Medicine earlier this year published guidelines for sitting from an international panel of experts, including Dr. Hedge. The panel recommends a combined two to four hours of standing and light activity spread throughout the workday. And research from NASA has found that standing up for two minutes 16 times a day while at work is an effective strategy for maintaining bone and muscle density, Dr. Hedge says.

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“The current scientific evidence shows that when people have occupations in which they are on their feet for more than two hours a day, there seems to be a reduction in the risk of developing key chronic diseases,” said John Buckley, a professor of applied exercise science at the University of Chester in England and lead author of the published guidelines. Among the guidelines’ eight authors, one of the other panel members disclosed a competing interest as owner of a website that sells sit-stand work products.

Other research aims to find ways to mitigate the adverse effects of too much sitting. A curious study, published last week in the American Journal of Preventive Medicine, looked at fidgeting. The researchers examined data from the UK Women’s Cohort Study, which has followed a large group of women for about 20 years. Nearly 13,000 of the women were asked to rate on a scale of 1 to 10 how much they fidget. Among women who were rated as the most sedentary, those who fidgeted a lot had the same risk of dying as those who weren’t especially sedentary. But women who didn’t fidget had an increased risk for mortality.

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