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Breaking-up periods of prolonged sedentary behaviour with light physical activity every day could reduce the risk of cancer death by 12%.

The findings, from a new study led by the University of Glasgow and published in PLOS Medicine, shed more light on the negative health impacts of having prolonged periods of sedentary behaviour every day.

Overall, the study found that sitting or reclining for more than 30 minutes at a time every day was associated with a higher risk of cancer death, with the risk increasing for each extra hour of continuous inactivity. However, the researchers also found that breaking-up sedentary behaviour with periods of physical activity could help to reduce a range of cancer risks. Those activities could be of light intensity, including slow walking or everyday tasks such as housework.

Long periods of sedentary behaviour, such as sitting or lying down while awake, is known to impact overall health, including being associated with an increased risk of cardiovascular disease and some cancers. However, until now less was known about the importance of how sedentary behaviour is accumulated, and if light activity would make a difference.

To better understand the impact different types of physical activity could have on cancer risks, the research team analysed data from wearable devices worn by more than 91,000 UK Biobank participants who were followed up for an average of 12 years.

The data showed that the total amount of prolonged inactivity (continuous inactivity for more than 30 minutes) was associated with cancer risks. Each additional hour of prolonged inactivity every day was associated with a 10% higher risk of cancer death. Crucially, the researchers demonstrated that this risk could be mitigated by replacing these long blocks of sitting with movement.

More specifically, the researchers found that the risk of cancer death was 12% lower when one hour of sedentary behaviour was replaced with light physical activity each day, including slow walking or household tasks such as ironing or dish washing.

Cancer death risk was also 8% lower when 30 minutes of inactivity was replaced with moderate physical activity each day, including walking at an average pace. For people who are busy but can engage with vigorous physical activity, like running, cancer death risk was 22% lower when 5 minutes of inactivity was replaced with 5 minutes of vigorous physical activity each day.

The research team say the findings highlight that it is not only the total amount of time spent sedentary, but also how sedentary time is accumulated, and whether it is broken up with physical activity of different intensities, that may be important for determining cancer death risk.

Dr Frederick Ho, lead author of the study from the University of Glasgow, said: “What our data shows is that sitting for more than 30 minutes at a time is particularly linked to a higher risk of cancer. The good news is that breaking up your sitting time with something as simple as a short walk could be protective.

"Current health guidelines focus heavily on moderate or vigorous exercise, but our findings show that light movement shouldn't be ignored. Moving forward, clinical trials will help us move beyond blanket advice and develop personalised strategies for breaking up sitting time."

The study, ‘Accelerometry-measured prolonged and interrupted sedentary behavior and cancer incidence and mortality: A cohort study of 91,292 UK Biobank participants’ is published in PLOS Medicine.

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Enquiries: ali.howard@glasgow.ac.uk or elizabeth.mcmeekin@glasgow.ac.uk

First published: 2 July 2026