July 15, 2026
ByLynne Christensen,
Staff Writer
- Reviewed byRobert H. Shmerling, MD,
Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
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Spending long periods sitting is a well-known health hazard, raising your risk for obesity, diabetes, heart disease, deep-vein thrombosis (a blood clot in a deep vein, usually in a leg), and some cancers
According to the federal physical activity guidelines, to counter such detrimental effects, people should generally move more and sit less. A study published July 2, 2026, in PLOS One, dug deeper to explore whether patterns of being sedentary and active make a difference for cancer risk
The researchers, including several from Harvard, analyzed data on over 91,000 adults from a large database of health information in the United Kingdom. Participants wore activity monitors on their wrists for seven days to measure physical activity and sedentary behavior, and were then followed for about 12 years. The researchers compared cancer risks among people who sat for 30 minutes or more without getting up and among those who intermittently stood up or moved around
The study found that every extra hour of unbroken sitting was linked to a 10% higher risk of dying from cancer. Swapping about one hour a day of prolonged sitting for light movement (walking, light chores) reduced the risk of cancer death by 12%. Replacing 30 minutes of prolonged sitting with moderate activity (brisk walking, more active housework) lowered the risk by 8%, and five minutes of vigorous activity rather than sitting was linked to 22% lower risk
Because this was an observational study, it can’t prove that replacing intermittent bouts of physical activity for prolonged sitting reduces cancer risk; more research is needed. However, the practical take-away message stands: try to avoid prolonged sitting. Set a timer to remind you to get up every so often. Walk around or do some light or moderate exercise. Even gentle activity breaks may help lower your risk for cancer and other health issues over time
Image: © MoMo Productions/Getty Images
About the Author
Lynne Christensen,
Staff Writer
Lynne Christensen is a staff writer who contributes articles to Harvard Health Publishing’s flagship website and its four newsletters: the Harvard Health Letter, Harvard Heart Letter, Harvard Women’s Health Watch, and Harvard Men’s Health Watch. She …
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About the Reviewer
Robert H. Shmerling, MD,
Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
Dr. Robert H. Shmerling is the former clinical chief of the division of rheumatology at Beth Israel Deaconess Medical Center (BIDMC), and is a current member of the corresponding faculty in medicine at Harvard Medical School. …
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View all posts by Robert H. Shmerling, MD
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