Being sedentary in moderation is unlikely to cause heart disease, according to a new review of past research.
Researchers concluded that only very high levels of sedentary time — more than 10 hours a day — are linked to an increased risk of heart attack, stroke or other cardiovascular-disease-related death.
Compared with sitting for less than three waking hours a day, more than 10 hours of sedentary time was tied to an 8 percent increase in the risk of developing heart disease, according to results in JAMA Cardiology.
“Our findings suggest that sedentary time is associated with increased risk of cardiovascular disease, independent of other potential risk factors such as body mass index and physical activity, only at very high levels,” said lead author Ambarish Pandey of the University of Texas Southwestern Medical Center in Dallas.
It hadn’t been clear how much sedentary time should be avoided to lower the risk of cardiovascular disease, Pandey said in an email.
The researchers analyzed data from nine long-term studies that had followed more than 700,000 adults and calculated the association between inactive time and the incidence of such events as heart attack and stroke. “Sedentary time” included any low-activity periods, including time spent sitting, watching TV or driving. Half of the studies followed people for more than 11 years.
People who were the most sedentary, about 12 hours a day, were 14 percent more likely than those who were sedentary only 2½ hours a day to develop cardiovascular disease. But more moderate amounts of sedentary time were not tied to increased risk.
Yeonju Kim, a research specialist at the University of Hawaii Cancer Center in Honolulu, who was not part of the new study, said more studies are needed before issuing a guideline, such as limiting sedentary time to less than 10 hours a day.
“There is previous literature to suggest that lower sedentary time is associated with higher cardiorespiratory fitness levels, which may underlie some of the observed association,” Pandey said.
Staying active and getting regular exercise can help lower cardiovascular disease risk, he said. “Increasing physical activity, avoiding prolonged sitting time, workplace interventions such as sit-stand work stations and activity-permissive desks may be useful to lower sedentary time,” he added.