A study by researchers at the University of Glasgow has found that sitting or reclining for more than 30 minutes at a time each day is linked to a higher risk of dying from cancer. The risk increases with each additional hour of continuous inactivity, but can be significantly reduced by replacing sedentary behaviour with physical activity.
Key Findings from the Study
The research, published in PLOS Medicine, analysed data from wearable devices worn by over 91,000 UK Biobank participants, who were followed for an average of 12 years. The findings show 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 per day was associated with a 10% higher risk of cancer death.
Benefits of Replacing Sedentary Behaviour
Scientists found that breaking up prolonged sedentary behaviour with physical activity can reduce the risk. The risk of cancer death was 12% lower when one hour of sedentary behaviour was replaced with light physical activity each day, such as slow walking or household tasks like ironing or dishwashing. Replacing 30 minutes of inactivity with moderate physical activity, like walking at an average pace, led to an 8% lower risk. Most notably, replacing five minutes of inactivity with five minutes of vigorous physical activity each day reduced the risk by 22%.
Expert Commentary
Dr Frederick Ho, lead author of the study, 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.”
Implications for Public Health
The study highlights the negative health impacts of prolonged sedentary behaviour on a daily basis. While long periods of sitting or lying down while awake have been associated with increased risk of cardiovascular disease and some cancers, this research provides new insights into the importance of how sedentary behaviour is accumulated. The findings suggest that even light intensity exercises, including slow walking or everyday tasks such as housework, can help reduce a range of cancer risks.
