By Nick Hodgson

Credit: Unsplash/CC0 Public Domain

Replacing 15 minutes of sleep or sedentary behavior with 15 minutes of movement was each linked to a 2% reduced risk of cancer, new UCL research has found.

The new study, published in BMC Medicine, analyzed the records of 59,218 people (55% female) with an average age of 61.7 years from the UK Biobank, a database of half a million volunteers taking part in medical research.

Smartwatches were used to track the daily movements of those people and, over an eight-year follow-up, some 2,385 cancer cases occurred in the group. Modeling was used to see how differences in daily movement were linked to cancer risk.

Previous research has found strong evidence that higher levels of activity are linked to a lower risk of several cancers—including bladder, breast, bowel, kidney and stomach cancers.

The UCL study, led by Dr. John Mitchell (UCL Division of Surgery and Interventional Science), looked at areas such as how long people spent sleeping, sedentary behavior such as watching TV, standing and movement at different intensities.

Proportional differences in movement (posture and intensity) and sleep compositions between participants with physical activity-related cancer vs. no cancer. Credit: BMC Medicine (2026). DOI: 10.1186/s12916-026-05069-3

They found that the more people moved, the lower their risk of cancer.

For example, replacing 15 minutes of sleep or sedentary behavior with 15 minutes of movement was each linked to a 2% reduced risk of cancer.

Conversely, swapping 30 minutes of movement for 30 minutes of sedentary behavior increased the risk by 8%, while swapping it for sleep increased the risk by 7%.

This was not just about doing more exercise, Mitchell said, but about how everyday activities like running for a bus or carrying home heavy bags of groceries can help maintain a healthy lifestyle and reduce the risk of cancer.

Mitchell said, "We are tending toward what we call 24-hour movement guidelines, where individuals have a menu of possible options that they can adapt to their lifestyle to help them mitigate their risk of disease over time.

"Our study showed that there's an increased risk of cancer for those who spend a lot of time sitting down.

"We also explored what might happen if people leading active lives reduced their levels of physical activity and found that they also face a higher cancer risk.

"Based on theoretical modeling, our study showed even losing two to three minutes per day of vigorous activity, such as running for a bus, and replacing it with sitting down, sleep or light activity increased their cancer risk.

"Other examples of vigorous activity—that is, anything that elevates your heart rate and makes you sweat—include sports, rushing up the stairs and carrying home heavy grocery bags.

"The take-home message is that for people already leading physically active lives, it's really important to maintain that level of activity as you get older."

Current NHS guidelines say adults should aim forat least 150 minutes of moderate-intensity activity a week or 75 minutes of vigorous-intensity activity a week.

They should also do strength activities that work all the major muscle groups (legs, hips, back, abdomen, chest, shoulders and arms) on at least two days a week.

Examples of moderate activity include very brisk walking (4 mph or faster), cycling at 10–12 mph, or badminton. Vigorous activity also includes hiking, jogging at 6 mph or faster, fast cycling, basketball or tennis.

More information: John J Mitchell et al, Device-measured movement behaviours and cancer incidence in a population sample of UK adults: Dual 24-hour analyses of postural and intensity compositions, BMC Medicine (2026). DOI: 10.1186/s12916-026-05069-3