Prolonged Sitting Tied to Higher Cancer Risk Even for Regular Exercisers, Study Finds
A new study has added to growing evidence that spending long hours sitting—even if you exercise regularly—may increase the risk of developing and dying from certain cancers. Researchers tracked over 91,000 adults for more than 12 years and found that each additional hour of uninterrupted sitting for more than 30 minutes was linked to about a 10% higher risk of cancer death.
The study, published in the journal PLOS Medicine, analysed data from participants who wore accelerometers to objectively measure their movement patterns. The findings challenge the common belief that a daily workout can fully offset the harms of a sedentary job or lifestyle.
“Regular exercise remains essential, but it should be combined with frequent movement throughout the day. Long, uninterrupted sitting appears to independently increase cancer risk and mortality,” said Dr Abhishek Shankar, assistant professor in the Department of Radiation Oncology at AIIMS Delhi, who was not involved in the study.
According to the researchers, prolonged sitting reduces muscle activity, impairs metabolism, and promotes insulin resistance, inflammation, weight gain, and hormonal changes. These factors may increase the risks of colorectal, breast, and endometrial cancers. The study also found that replacing sitting time with physical activity was linked to a lower cancer risk.
The authors cautioned that the observational study does not prove causation, but noted that the use of wearable device-based tracking strengthens the evidence compared to self-reported data. They recommend that workplaces and individuals incorporate regular breaks from sitting—such as standing, walking, or stretching every 30 minutes—to reduce potential health risks.
Dr Shankar added, “For people with desk jobs, simple changes like using height-adjustable desks, taking short walks after meals, or holding standing meetings could make a meaningful difference.” The study underscores that while exercise is beneficial, it cannot fully compensate for many hours of inactivity spread across the day.
